Commercial Energy Autopilot · Validation prototype 2.8
Illustrative · not a quotation
Watt Next · independent calculator test
The calculator is ready for testing. Survey and proposal drafts are available through the survey builder. Records save only in this browser on this device; export backups regularly. The Training Academy and sales playbook are available. Shared CRM and supporting pages are still awaiting transfer. The calculator starts with a fictional example.
Open the interactive calculator
If the buttons do not respond or figures are blank, use the web app:
Open in Safari or your browser. Sign in with your ChatGPT account if asked.
Completed demonstration · fictional customer
100,000 kWh/year · cash installation · 28p day / 10p night / 8p export. Figures, access choices and tariffs are editable. No survey, authority or DNO approval is claimed.
Surveyor assumptions
Synthetic test sites; loading one replaces the current assumptions.
A generic hourly commercial demand profile with adjustable daytime share and seasonal PV profile are used. Set the night tariff window and price using the overnight force-charging sliders. Battery power is assumed to be 0.25 × capacity (kW) and round-trip efficiency 81%. Actual half-hourly meter data, roof design, tariffs and supplier quotations must replace these assumptions before a customer proposal.
Your business · start here
Tell us about the site, then let Autopilot find a suitable starting point.
Opens a Google search for this address in a new tab. A postcode may cover several properties; confirm the exact building. Only the address is sent when you click. If Earth does not load, try Maps.
Use the annual consumption on the electricity bill.
Enter the actual panel rating, for example 475. Panel area remains an approximate 2.2m² allowance.
Fixed size keeps the solar capacity entered below, rounded down only if necessary to fit whole panels. Essential Solar remains a separately labelled smaller-budget alternative.
Quick roof estimate · image or measurements
Use each area for a separate roof face or a matching pair. Do not enter the same face twice. The opposite-side option assumes a matching face with the same dimensions and pitch.
Roof area 1
Start with the roof side assumed closest to south. Add whichever measurements you know; leave the rest blank. A centred image helps identify the roof, but cannot establish metres without a scale or known dimension. ChatGPT image review is a separate step; this page does not automatically analyse photographs.
Preview only, held on this page until reload. The image is not sent to ChatGPT or carried into the proposal automatically. Use Add roof image to proposal in the Survey Builder for your finished illustration.
For a symmetrical apex roof, the horizontal width of one side is half the whole building span.
Editable spacing allowance; confirm the mounting system. The 500 mm allowance is around the roof-face perimeter, not between panels.
Manually deduct space for rooflights, access and obstructions; placement still needs review.
If pitch is unknown, the geometric check assumes 30° for horizontal depth. This is a working assumption, not a roof measurement. For flat roofs enter 0°; tilted panel rows need a separate spacing design.
Only an image or one dimension? Get a visual estimate with ChatGPT
Copy this prompt into our ChatGPT conversation and attach your centred roof image there. Add a visible map scale or one approximate dimension if possible. Without either, treat the suggested range as low confidence.
Add both roof dimensions for the geometric check, or use ChatGPT to review the image and enter a conservative panel range above. A missing dimension is never invented here.
Uses 1.1 × 1.9 m panels and a 0.5 m allowance at each roof-face edge. Portrait wins a tie; landscape is selected when it fits more. This 500 mm assumption is not a verified design setback. Check the ridge, rooflights, access, structure and mounting requirements. The side closest to south is an unverified assumption; map orientation is unchanged.
A space estimate is not a confirmed design. Applying a starting count updates the available-space input only; click Find the best option for my business to recalculate. Included roof faces are counted for available space; generation is not calculated separately by orientation. The opposite side may generate less electricity, so do not assume that twice the panels means twice the generation. A flat-roof tilted array also needs row-spacing design beyond this simple fit.
Roof area 2
Start with the roof side assumed closest to south. Add whichever measurements you know; leave the rest blank. A centred image helps identify the roof, but cannot establish metres without a scale or known dimension. ChatGPT image review is a separate step; this page does not automatically analyse photographs.
Preview only, held on this page until reload. The image is not sent to ChatGPT or carried into the proposal automatically. Use Add roof image to proposal in the Survey Builder for your finished illustration.
For a symmetrical apex roof, the horizontal width of one side is half the whole building span.
Editable spacing allowance; confirm the mounting system. The 500 mm allowance is around the roof-face perimeter, not between panels.
Manually deduct space for rooflights, access and obstructions; placement still needs review.
If pitch is unknown, the geometric check assumes 30° for horizontal depth. This is a working assumption, not a roof measurement. For flat roofs enter 0°; tilted panel rows need a separate spacing design.
Only an image or one dimension? Get a visual estimate with ChatGPT
Copy this prompt into our ChatGPT conversation and attach your centred roof image there. Add a visible map scale or one approximate dimension if possible. Without either, treat the suggested range as low confidence.
Add both roof dimensions for the geometric check, or use ChatGPT to review the image and enter a conservative panel range above. A missing dimension is never invented here.
Uses 1.1 × 1.9 m panels and a 0.5 m allowance at each roof-face edge. Portrait wins a tie; landscape is selected when it fits more. This 500 mm assumption is not a verified design setback. Check the ridge, rooflights, access, structure and mounting requirements. The side closest to south is an unverified assumption; map orientation is unchanged.
A space estimate is not a confirmed design. Applying a starting count updates the available-space input only; click Find the best option for my business to recalculate. Included roof faces are counted for available space; generation is not calculated separately by orientation. The opposite side may generate less electricity, so do not assume that twice the panels means twice the generation. A flat-roof tilted array also needs row-spacing design beyond this simple fit.
Roof area 3
Start with the roof side assumed closest to south. Add whichever measurements you know; leave the rest blank. A centred image helps identify the roof, but cannot establish metres without a scale or known dimension. ChatGPT image review is a separate step; this page does not automatically analyse photographs.
Preview only, held on this page until reload. The image is not sent to ChatGPT or carried into the proposal automatically. Use Add roof image to proposal in the Survey Builder for your finished illustration.
For a symmetrical apex roof, the horizontal width of one side is half the whole building span.
Editable spacing allowance; confirm the mounting system. The 500 mm allowance is around the roof-face perimeter, not between panels.
Manually deduct space for rooflights, access and obstructions; placement still needs review.
If pitch is unknown, the geometric check assumes 30° for horizontal depth. This is a working assumption, not a roof measurement. For flat roofs enter 0°; tilted panel rows need a separate spacing design.
Only an image or one dimension? Get a visual estimate with ChatGPT
Copy this prompt into our ChatGPT conversation and attach your centred roof image there. Add a visible map scale or one approximate dimension if possible. Without either, treat the suggested range as low confidence.
Add both roof dimensions for the geometric check, or use ChatGPT to review the image and enter a conservative panel range above. A missing dimension is never invented here.
Uses 1.1 × 1.9 m panels and a 0.5 m allowance at each roof-face edge. Portrait wins a tie; landscape is selected when it fits more. This 500 mm assumption is not a verified design setback. Check the ridge, rooflights, access, structure and mounting requirements. The side closest to south is an unverified assumption; map orientation is unchanged.
A space estimate is not a confirmed design. Applying a starting count updates the available-space input only; click Find the best option for my business to recalculate. Included roof faces are counted for available space; generation is not calculated separately by orientation. The opposite side may generate less electricity, so do not assume that twice the panels means twice the generation. A flat-roof tilted array also needs row-spacing design beyond this simple fit.
Roof area 4
Start with the roof side assumed closest to south. Add whichever measurements you know; leave the rest blank. A centred image helps identify the roof, but cannot establish metres without a scale or known dimension. ChatGPT image review is a separate step; this page does not automatically analyse photographs.
Preview only, held on this page until reload. The image is not sent to ChatGPT or carried into the proposal automatically. Use Add roof image to proposal in the Survey Builder for your finished illustration.
For a symmetrical apex roof, the horizontal width of one side is half the whole building span.
Editable spacing allowance; confirm the mounting system. The 500 mm allowance is around the roof-face perimeter, not between panels.
Manually deduct space for rooflights, access and obstructions; placement still needs review.
If pitch is unknown, the geometric check assumes 30° for horizontal depth. This is a working assumption, not a roof measurement. For flat roofs enter 0°; tilted panel rows need a separate spacing design.
Only an image or one dimension? Get a visual estimate with ChatGPT
Copy this prompt into our ChatGPT conversation and attach your centred roof image there. Add a visible map scale or one approximate dimension if possible. Without either, treat the suggested range as low confidence.
Add both roof dimensions for the geometric check, or use ChatGPT to review the image and enter a conservative panel range above. A missing dimension is never invented here.
Uses 1.1 × 1.9 m panels and a 0.5 m allowance at each roof-face edge. Portrait wins a tie; landscape is selected when it fits more. This 500 mm assumption is not a verified design setback. Check the ridge, rooflights, access, structure and mounting requirements. The side closest to south is an unverified assumption; map orientation is unchanged.
A space estimate is not a confirmed design. Applying a starting count updates the available-space input only; click Find the best option for my business to recalculate. Included roof faces are counted for available space; generation is not calculated separately by orientation. The opposite side may generate less electricity, so do not assume that twice the panels means twice the generation. A flat-roof tilted array also needs row-spacing design beyond this simple fit.
Complete dimensions or a visual starting count for each selected roof area to see the combined estimate.
Starting tariffs: 28p day, 10p night, 8p export; annual price change 3.1%. Overnight window starts at midnight and initially ends at 07:00. All are adjustable. Higher peak rates can be added below after the first calculation.
Available space is a limit, not a commitment to install that size. Panel and area estimates use planning your entered panel wattage and an approximate 2.2m² per panel, before survey.
Example Manufacturing Business (demonstration) · 100,000 kWh/year · 100 kWp available solar limit. COMPLETED DEMONSTRATION: modelled usage and tariffs; no real survey or authority. Access allowances are shown for discussion and excluded until enabled.
Editable starting assumptions, not a supplier quote. Change rates in Surveyor View or use the overnight charging slider below.
Standard electricity rate: 0.801p/kWh from 1 April 2026 to 31 March 2027. Check the bill for exemptions or relief, including low-use supplies. Eligibility depends on the actual supply and billing period; the calculator does not automatically remove the levy when imports fall. Enter an adjusted main rate if needed. This is added to day, night and peak imports, including battery charging, never to export income. Choose already included to avoid double counting. The screening forecast applies the electricity-price growth assumption to the combined rate; it does not forecast statutory levy changes. HMRC rates
CCL added at 0.801p/kWh on grid imports, including charging. Effective imports: day 28.801p / night 10.801p. Year-one net levy saving: £357 (included in the savings, not an extra amount to add).
How should your battery charge?
Use spare solar, cheaper overnight electricity, or a mix of both. Autopilot compares the options using your figures.
Autopilot will compare the three approaches and show the strongest tested option for your figures.
Adjust overnight tariff and charging settings
Use the night price and hours from the customer’s tariff. We can fine-tune the charging settings during the technical review.
The cheap window starts at midnight. Its duration controls both existing building use charged at the night rate and the hours available to charge the battery. Outside this window, the day rate applies unless the optional peak rate is active. Charging power, remaining capacity and losses still limit how much can be stored. For partial overnight charging, 50% means top up from the grid only until the battery is half full, aiming to leave the other half for surplus solar the next day. For example, a 20 kWh modelled battery targets 10 kWh stored overnight, with up to 10 kWh space for solar. If already above the target, the battery is not emptied to make space. Sunlight, available surplus and charging limits determine what actually happens. This is a fixed setting, not a weather forecast. The slider applies to partial charging; Autopilot compares it with solar-only and full overnight charging.
Avoid expensive peak electricity
40p and 4–7pm are editable examples, not a supplier quote. Use the peak rate from the same tariff as your day and night rates. Peak pricing applies to all grid electricity used in those hours, including any demand the battery cannot cover.
Peak pricing is off — the agreed day and night rates apply.
Could AIA improve your cash flow?
Explore the potential tax benefit of Annual Investment Allowance alongside your energy savings.
Read HMRC’s official AIA guidance ↗ · AIA is a deduction from taxable profits, not an automatic cash grant. Your accountant should confirm qualifying expenditure, available allowance and when the benefit can be used.
Quick screening only. Answer for the business buying this system; your accountant must confirm eligibility, qualifying costs, rate and timing.
Tax amount and timing assumptions
£1m is the standard annual limit, not a confirmed balance. Adjust for other spending, group sharing and short accounting periods.
100% is an illustration. Exclude non-qualifying work and private use. Prices already exclude VAT; recoverable VAT is not added to the claim.
25% is an editable example, not a rate assigned to your business. Use an accountant-confirmed effective rate allowing for profit bands and marginal relief.
18 months is a placeholder, not a tax deadline. Use the expected reduced tax payment or refund date. This is separate from the accounting period of the claim.
AIA is off.
When is AIA claimed, and what does this illustration leave out?
AIA is claimed in the accounting period of qualifying expenditure, through the appropriate tax return. The cash benefit occurs when tax payable is reduced or a repayment is received. For many smaller companies, Corporation Tax is payable nine months and one day after the accounting period ends; different rules can apply.
The illustration adds one estimated AIA benefit to otherwise pre-tax project cash flow. It is not a complete after-tax forecast: tax on energy savings and exports, other deductions, loss relief, future replacement allowances, disposal adjustments and changes in tax rates are not calculated. AIA accelerates relief; a business without an AIA claim may still receive other capital allowances, which are not modelled here.
Finance does not automatically prevent AIA, but ownership and the agreement matter. Hire-purchase timing needs checking and interest is not AIA expenditure. Cash-basis businesses may receive relief through a different route; they are not modelled as AIA here. Autopilot continues to rank systems before tax. The AIA check resets when you apply new site details, so one customer’s tax assumptions are not carried into another assessment.
Recommended starting point for Example Manufacturing Business (demonstration)
Autopilot suggests 50 kWp solar without a battery. This uses your 100,000 kWh annual consumption, 77% daytime share, seven-day use and 100 kWp solar space limit. A battery does not improve the recommended value enough under these assumptions; you can still compare one below. Autopilot prioritises the shortest modelled whole-system cash payback before finance and tax, including maintenance and replacement allowances. A smaller battery or no battery may recover the investment sooner. Long-Term prioritises 25-year value instead.
Recommended solar / battery
50 kWp / 0 kWh
Total project investment
£41,368
Year-one operating benefit
£11,902/year
Average regular monthly benefit, before finance
£992
Payback before tax
3.4 years (approx.)
Extra battery investment
£0
Explore a different size
Starting guide: 50 kWp solar pairs with 25 kWh storage; 100 kWp pairs with 50 kWh. Rounded to the nearest whole kWh and capped by your battery limit. This is a sizing preference, not a guarantee of the best payback. Autopilot still compares against no battery. Manual sliders remain adjustable.
Move either slider to update the figures below. Solar is limited to the available space entered above.
50 kWp · 100 × 500W panels
0 kWh
10% means 10% less solar generation, not 10% of the roof shaded. Applied evenly across the year as a screening estimate. Final design must assess shade timing and string layout. Only add shading losses not already included in the generation estimate.
Selected system
50 kWp / 0 kWh
Total project investment
£41,368
Net benefit in year one
£11,902/year
Monthly benefit
£992/month
Battery extra cost
£0
Payback before tax
3.4 years (approx.)
Move a slider to see the selected price, savings and payback here immediately. Estimates include maintenance; prices exclude VAT.
Selected solution
Project cost
£41,368
Year-one net operating benefit
£11,902
25-year benefit
£366,768
25-year NPV at 5%
£174,581
Payback before tax
3.4 years (approx.)
Annual PV generation
47,025 kWh
Solar retained on site
94.7%
Solar delivered after battery losses
44,529 kWh/year
Battery selected
0 kWh
No battery selected
Battery extra cost
£0
Added to the solar-only investment
Battery extra yearly benefit
£0/year
After charging costs and losses
Battery-only payback
Not selected
Includes forecast replacement costs
Solar-only solution selected. Move the battery slider to see the extra investment, yearly benefit and battery payback here.
How the battery figures are calculated
Battery cards follow your selected solution and update as you move the sliders. They compare the same solar size, tariff and care plan with and without the selected battery. Cost includes any selected EPS upgrade and changes to site-allowance credits. Benefits are after charging costs and losses, before finance and tax.
Battery payback uses the 25-year cash forecast, including the year-13 battery replacement allowance. It is separate from whole-project payback above. No separate tariff-switch saving is added to the cards. An emergency reserve is not yet modelled and may reduce savings.
Compare a different tariff for the battery option
Current tariff uses the window set by the overnight force-charging slider. The alternate cheap window starts at midnight. The peak settings above apply to both tariff options. Standing charges are assumed unchanged. The synthetic load profile must be replaced by actual interval data for final advice.
Suggested approach for your business
Overnight charging
Aim to fill at the cheaper night rate for use during the day.
£1,421/year
Estimated extra benefit versus the same solar system without a battery, after charging costs. Before finance and tax.
See the other charging approaches
Alternative
Solar charging
Store spare solar power to use later.
£382/yearEstimated extra benefit versus solar without a battery
Alternative
Balanced charging
Use a mix of spare solar and cheaper overnight electricity.
£982/yearEstimated extra benefit versus solar without a battery
Shown above
Overnight charging
Aim to fill at the cheaper night rate for use during the day.
£1,421/yearEstimated extra benefit versus solar without a battery
These are alternative ways to run the same battery. The savings are alternatives, not amounts to add together. Final settings depend on your tariff and site checks.
Detailed charging calculations · Surveyor View
Three charging strategies — same equipment and tariff
Strategy
Extra annual battery benefit
Extra battery NPV
Solar charging input (kWh/year)
Grid charging input (kWh/year)
Battery output: solar / grid (kWh/year)
Solar charging only
£382
£-7,125
2,493
0
2,019 / 0
Partial overnight charging (50% target)
£982
£3,828
2,262
5,069
1,832 / 4,106
Full overnight charging · selected
£1,421
£11,845
983
10,139
796 / 8,213
Extra benefits are measured against solar-only on the same battery-option tariff. Solar retained on site includes solar sent to storage. Solar delivered to the building excludes storage losses and any energy still in the battery at year end. Grid-charged battery output is excluded from both solar figures. Solar diversion reduces export income; it is not counted as free profit. Source tracking uses proportional mixing of stored solar and grid energy. Partial charging leaves room at the overnight target; solar and demand determine the actual space later. This is a comparison of three rules, not forecast-based or globally optimal dispatch.
Selected: 50 kWp solar and 0 kWh storage. Modelled savings include on-site solar use, exported energy and battery discharge net of overnight charging costs. Charging strategy: no battery. Equipment replacements are budgeted in years 13 (battery) and 15 (inverter), not guaranteed.
Confidence: Amber — preliminary estimate. Actual half-hourly consumption, tariff evidence and technical survey are needed.
Which option works best for your business?
Compare what you put in, what could be left each month, and the longer-term benefit.
Compare other optionsHow Autopilot chooses
Solar sizes tested from 10–100 kWp and batteries 0–80 kWh. Default battery sizing compares no battery with approximately half the solar kWp expressed in kWh; all-size mode also tests battery-only candidates. Manual sizes override this preference. Essential Solar searches for a smaller, viable solar-only system, aiming for capital cost at or below 65% of the Sweet Spot, with customer-arranged upkeep. It retains a basic maintenance allowance, installation extras and inverter replacement provision; no equipment discount or reduced safety specification is assumed. Where no viable smaller system exists, the same solar size may be offered with a different service scope, or no Essential investment is shown. Sweet Spot prioritises the shortest whole-system operating payback among positive-NPV candidates, using fractional years interpolated from annual cash flows. Equal payback favours greater first-year benefit, then lower cost. Ranking is before finance and tax. Fixed-size mode restricts Sweet Spot and Long-Term to the chosen whole-panel solar capacity; Essential Solar is a smaller-budget alternative. Long-Term retains the highest modelled 25-year NPV. Options can coincide when the model does not support distinct choices. Battery candidates use the selected charging rule, or all three tested rules in Autopilot strategy mode. When peak pricing is enabled, Autopilot can also compare normal battery use with holding charge for peak hours. Compare repayment affordability separately; payback timing within a year is approximate. This is a grid search under the stated dispatch rules, not a globally optimal design.
Currently selected: Sweet Spot. The Sweet Spot is Autopilot’s suggested starting point, based on return relative to investment.
Alternative to compare
Essential Solar
Solar only · customer-arranged upkeep
30 kWp solar · 0 kWh battery
Customer-arranged upkeep Own equipment app where supported; no head-office monitoring or optimisation contract. Year-one upkeep budget: £490 · included in these figures.
Your upfront investment
£26,421
Indicative project price, excluding VAT.
Average regular monthly benefit
£628 /month
Year 1 average after maintenance. Available benefit, not a guaranteed payment. One-off tax relief is separate.
Net cash benefit by year 10
£58,396
After recovering the upfront investment and paying modelled costs.
Estimated payback
Year 4
Net benefit by year 25
£231,633
Autopilot recommendation
Sweet Spot
Balance the investment and the return
50 kWp solar · 0 kWh battery
Care · cleaning and full planned maintenance · proposed managed care Head-office monitoring and optimisation as described in the proposed service scope. Year-one upkeep budget: £1,000 · included in these figures.
Your upfront investment
£41,368
Indicative project price, excluding VAT.
Average regular monthly benefit
£992 /month
Year 1 average after maintenance. Available benefit, not a guaranteed payment. One-off tax relief is separate.
Net cash benefit by year 10
£92,531
After recovering the upfront investment and paying modelled costs.
Estimated payback
Year 4
Net benefit by year 25
£366,768
Alternative to compare
Long-Term
Focus on long-term financial value
100 kWp solar · 50 kWh battery
Care · cleaning and full planned maintenance · proposed managed care Head-office monitoring and optimisation as described in the proposed service scope. Year-one upkeep budget: £1,500 · included in these figures.
Your upfront investment
£97,421
Indicative project price, excluding VAT.
Average regular monthly benefit
£1,729 /month
Year 1 average after maintenance. Available benefit, not a guaranteed payment. One-off tax relief is separate.
Net cash benefit by year 10
£135,944
After recovering the upfront investment and paying modelled costs.
Estimated payback
Year 5
Net benefit by year 25
£601,000
Net cash benefit includes upfront investment, maintenance, any finance repayments and the replacement allowances when due. Tax effects are excluded. The default deposit is 10% of each option’s installation contract price; any included customer-arranged access costs are paid upfront in addition and are not financed. If you adjust the deposit amount, that same amount applies to each option, capped at its price. The loan rate and term apply to all options. Essential Solar uses the basic customer-arranged upkeep allowance; other options use the selected maintenance plan. The equipment price assumptions are the same: no cheaper brand or reduced safety specification is assumed. Monthly benefits are first-year averages, not equal monthly receipts. Autopilot ranks packages before tax and finance. Forecasts are estimates, not guarantees.
See the year-by-year comparison
Year-end cumulative benefit after upfront cost and modelled costs. Figures exclude other tax effects.
Cash-flow comparison
Essential Solar
Sweet Spot
Long-Term
Project price
£26,421
£41,368
£97,421
Upfront cash
£26,421
£41,368
£97,421
Maintenance / upkeep scope
Customer-arranged upkeep
Care · cleaning and full planned maintenance
Care · cleaning and full planned maintenance
Year-one upkeep allowance
£490
£1,000
£1,500
Monthly loan repayment
£0
£0
£0
Estimated AIA benefit / timing
Not included
Not included
Not included
Net benefit by year 1
-£18,882
-£29,467
-£76,678
Net benefit by year 2
-£11,147
-£17,257
-£55,397
Net benefit by year 3
-£3,212
-£4,730
-£33,565
Net benefit by year 4
£4,929
£8,121
-£11,167
Net benefit by year 5
£13,280
£21,305
£11,811
Net benefit by year 6
£21,848
£34,831
£35,384
Net benefit by year 7
£30,638
£48,707
£59,568
Net benefit by year 8
£39,655
£62,943
£84,379
Net benefit by year 9
£48,906
£77,548
£109,832
Net benefit by year 10
£58,396
£92,531
£135,944
Net benefit by year 11
£68,133
£107,903
£162,733
Net benefit by year 12
£78,121
£123,673
£190,216
Net benefit by year 13
£88,368
£139,851
£206,411
Net benefit by year 14
£98,881
£156,449
£235,336
Net benefit by year 15
£107,165
£170,228
£258,511
Net benefit by year 16
£118,229
£187,697
£288,954
Net benefit by year 17
£129,580
£205,619
£320,186
Net benefit by year 18
£141,225
£224,006
£352,227
Net benefit by year 19
£153,171
£242,869
£385,099
Net benefit by year 20
£165,426
£262,221
£418,821
Net benefit by year 21
£177,999
£282,074
£453,417
Net benefit by year 22
£190,898
£302,442
£488,910
Net benefit by year 23
£204,131
£323,338
£525,322
Net benefit by year 24
£217,706
£344,775
£562,677
Net benefit by year 25
£231,633
£366,768
£601,000
See regular monthly benefit · first year
After maintenance and any loan repayments. These monthly figures exclude the one-off AIA benefit, which appears separately in the annual comparison.
Cash-flow comparison
Essential Solar
Sweet Spot
Long-Term
Jan
£160
£252
£762
Feb
£313
£507
£1,241
Mar
£603
£986
£1,977
Apr
£869
£1,414
£2,210
May
£1,057
£1,638
£2,415
Jun
£1,118
£1,681
£2,442
Jul
£1,080
£1,661
£2,439
Aug
£947
£1,517
£2,289
Sep
£708
£1,154
£2,036
Oct
£426
£695
£1,630
Nov
£160
£252
£755
Dec
£96
£145
£547
SEE WHAT YOUR CHOICES CHANGE
Your energy advantage.
Move the solar and battery sliders above. Watch your modelled savings and energy mix respond.
● LIVE WITH YOUR SLIDERS
Annual savings
Your whole solution
£11,902 /year
After care and charging. Before finance and tax.
Solar share
Less reliance on the grid
45%of annual use
Your electricity supplied by solar. Grid-charged battery output excluded.
Emissions saved
Your estimated annual change
5.83 t CO₂e/year
Estimated reduction in grid emissions. Includes battery charging losses.
Battery savings
Extra yearly savings from storage
£0 extra savings /year
No battery selected. Add storage to see its extra saving and cost.
Upfront investment£41,368
Operating payback3.4 years (approx.)
Battery investment£0
Modelled first-year results. Dial scales stay fixed while you change solar and battery sizes. The battery scale uses the storage limit and tariff assumptions as a guide, not a savings target. Any actual negative battery saving is clearly labelled. Battery payback includes forecast replacement costs and excludes finance and tax. Extra site costs affect investment and payback; they do not directly change annual energy savings.
How electricity reaches your business
Solar used directly44,529 kWh/year →
Solar via your battery0 kWh/year →
Grid via your battery0 kWh/year →
Grid used directly55,471 kWh/year →
45%powered by your roof
Your business 100,000 kWh/year
☀ Spare solar exported: 2,496 kWh/year Shown separately from electricity used by your business.
Beyond the bill.
Measurable energy indicators to support your sustainability conversations.
01 · GENERATE47,025 kWhSolar electricity generated in year one
02 · USE ON SITE44,529 kWhSolar delivered to your business, after storage losses
03 · GRID EMISSIONS5.83 t CO₂eEstimated reduction from fewer grid purchases
Set the customer’s own target to track progress.
What these figures mean for your CSR reporting
Uses the UK government 2026 electricity-generated factor of 0.13096 kg CO₂e/kWh. Baseline grid purchases 100,000 kWh/year; with this solution 55,471 kWh/year, including grid charging. Estimated location-based operational grid-emissions change = difference × factor. Exported solar is not credited to the business’s own emissions estimate. Electricity shifting alone is not assumed to save carbon. Investment costs change payback; they do not directly change annual operating savings.
These are modelled year-one indicators, not a verified carbon footprint, net-zero claim or certificate. Validate them with generation and import/export meter data after installation. Agree an annual review of actual generation, solar use, imports and maintenance findings, and compare these with the customer’s own targets. Grid-charged battery output is kept separate from solar electricity.
Carbon estimate excludes equipment manufacture, construction, transport, end-of-life and export credits. It uses a constant annual average and does not simulate hourly emissions, future grid decarbonisation or contractual/market-based reporting. UK government 2026 emissions factors and methodology ↗
Your investment and savings over time
Estimated year-one net savings
£11,902
Average regular monthly benefit
£992
Estimated payback
Year 4
Amber markers show replacement allowances already deducted from cash flow. These are planning budgets, not guaranteed failure dates or included maintenance cover.
Net cash benefit by year 5
£21,305
Net cash benefit by year 10
£92,531
Net cash benefit by year 25
£366,768
Starts with your purchase cost of £41,368. The payback marker is the first year-end when cumulative savings cover the investment. Running costs and modelled replacement allowances are included. Replacement spending may cause dips in years 13 (battery) and 15 (inverter). Prices change by the editable 3.1% annual assumption. Estimates exclude tax effects. Estimates are not guaranteed.
See year-by-year amounts
Year
Operating benefit less repayments, before replacements
Battery replacement allowance
Inverter replacement allowance
Estimated AIA benefit
Net cash flow that year
Cumulative net cash flow
Upfront
-£41,368
£0
£0
£0
-£41,368
-£41,368
1
£11,902
£0
£0
£0
£11,902
-£29,467
2
£12,210
£0
£0
£0
£12,210
-£17,257
3
£12,526
£0
£0
£0
£12,526
-£4,730
4
£12,851
£0
£0
£0
£12,851
£8,121
5
£13,184
£0
£0
£0
£13,184
£21,305
6
£13,526
£0
£0
£0
£13,526
£34,831
7
£13,876
£0
£0
£0
£13,876
£48,707
8
£14,236
£0
£0
£0
£14,236
£62,943
9
£14,605
£0
£0
£0
£14,605
£77,548
10
£14,983
£0
£0
£0
£14,983
£92,531
11
£15,372
£0
£0
£0
£15,372
£107,903
12
£15,770
£0
£0
£0
£15,770
£123,673
13
£16,179
£0
£0
£0
£16,179
£139,851
14
£16,598
£0
£0
£0
£16,598
£156,449
15
£17,028
£0
-£3,250
£0
£13,778
£170,228
16
£17,469
£0
£0
£0
£17,469
£187,697
17
£17,922
£0
£0
£0
£17,922
£205,619
18
£18,387
£0
£0
£0
£18,387
£224,006
19
£18,863
£0
£0
£0
£18,863
£242,869
20
£19,352
£0
£0
£0
£19,352
£262,221
21
£19,853
£0
£0
£0
£19,853
£282,074
22
£20,368
£0
£0
£0
£20,368
£302,442
23
£20,896
£0
£0
£0
£20,896
£323,338
24
£21,437
£0
£0
£0
£21,437
£344,775
25
£21,993
£0
£0
£0
£21,993
£366,768
See monthly cash flow — first year
Monthly cash benefit after running costs and, when selected, finance repayments. An estimated AIA benefit is included once if its selected timing falls in the first 12 months; the table separates it from regular savings. Upfront investment and future equipment replacement costs are shown in the main graph. Scroll sideways on smaller screens to read every amount.
Month
Regular benefit
Estimated AIA benefit
Total cash benefit
Jan
£252
£0
£252
Feb
£507
£0
£507
Mar
£986
£0
£986
Apr
£1,414
£0
£1,414
May
£1,638
£0
£1,638
Jun
£1,681
£0
£1,681
Jul
£1,661
£0
£1,661
Aug
£1,517
£0
£1,517
Sep
£1,154
£0
£1,154
Oct
£695
£0
£695
Nov
£252
£0
£252
Dec
£145
£0
£145
Finance and maintenance
Defaults to 10% of the selected price. Move the slider to choose your own amount.
Care · cleaning and full planned maintenance · year one
£83.33/month · £1,000/year
Cleaning, full planned maintenance, head-office monitoring and continued optimisation in one monthly care package.
Watt Next Care is a separate agreement directly with Adrian Bruce, trading as Watt Next, paid monthly from commissioning, including cash installations. Separate written acceptance is required; the DNO-first authority does not accept Care. It is separate from the installer’s contract, installation price, deposit and finance repayments.
Already deducted from the savings and cash-flow figures, so do not subtract it again. Final service scope, monthly price and terms are confirmed in the surveyed quotation. Prices exclude VAT; care costs rise by an assumed 2.5% a year in the forecast.
What does each maintenance option cover?
Care and Enhanced Care are separately accepted Watt Next Care agreements. Watt Next may use qualified contractors and remains responsible for its contracted service. Agree price/VAT, start date, service hours, response times, term, renewal, cancellation and annual price reviews. Installer and manufacturer warranties remain separate. No generation, savings or fire-prevention guarantee is included.
Cleaning and full planned maintenance are included to the agreed schedule. Confirm the service schedule and safe-access method at survey. Unscheduled repairs, access equipment and replacement parts must be itemised if covered; full planned maintenance does not mean unlimited free repairs.
Year-one care costs for the selected 50 kWp solar / 0 kWh battery system
Option
Annual cost
Monthly payment / budget
Basic maintenance allowance
£650
£54.17 equivalent only
Care · cleaning and full planned maintenance · selected
£1,000
£83.33/month
Enhanced Care
£1,650
£137.50/month
Care · cleaning and full planned maintenance · service scope
Head-office monitoring
Remote fault and generation review by our head office during agreed working hours, alongside your own equipment app. Requires compatible monitoring and a working internet connection; not a 24-hour emergency service.
Preventive maintenance
One planned inspection each year, with a service report, accessible equipment checks and an agreed electrical testing schedule.
Safety review
Review accessible DC connections, containment, isolators, labels and fitted protective devices. Review arc-fault alerts and detection settings where supported, plus fitted arc-box protection. Record defects for corrective action.
Continued optimisation
Quarterly remote performance review, including battery schedules and available tariff settings. Changes remain within equipment, warranty and site limits; no extra savings are assumed in this forecast.
Warranty support
Help identifying faults and administering valid manufacturer warranty claims. Parts, labour, access and carriage are covered only where the applicable warranty or written service schedule says so.
Annual panel cleaning
One routine panel clean each year using the surveyed, agreed method. Specialist contamination removal and access equipment are separately quoted unless included in the service schedule.
Full planned maintenance
Scheduled servicing, agreed electrical testing, fault investigation and warranty coordination. Repair labour, call-outs and replacement parts are included only where itemised in the written service schedule.
Access, safety and replacement costs
MEWPs, scaffolding, loading platforms, roof repairs, specialist fire-risk assessments, emergency call-outs and remedial works are separately quoted unless itemised as included. Safety checks support the site fire strategy; they do not certify a building fire-safe. Arc-fault detection depends on installed equipment.
The forecast separately deducts a battery replacement allowance in year 13 and a PV inverter replacement allowance in year 15 where selected. These are future expenses, not a replacement fund or free replacements within the monthly care fee.
How care is priced in this illustration
Basic allowance: £250 + £8 per kWp a year; Care: £500 + £10 per kWp; Enhanced Care: £950 + £14 per kWp. Battery-only systems use the base allowance. These screening rates need a surveyed service quotation, including the agreed annual clean. The model increases care costs by 2.5% a year. Cash payment for installation does not remove the monthly care payment.
Performance protection · an option we are developing
A measurable promise, with clear accountability. We are exploring a separately priced performance guarantee for eligible systems. It is not included in the maintenance allowance or savings forecast shown here.
The proposed approach would compare measured annual generation with an agreed, weather-adjusted site benchmark, allowing for normal panel degradation. The benchmark would come from the final surveyed design, not this screening calculator.
If an eligible shortfall occurs, the proposed service would investigate the cause, arrange corrective work within the agreed scope and apply a defined remedy for any covered shortfall. The measurement method, response times, credit value, annual cap, term and funding must be agreed before a guarantee can be offered.
Written terms would explain grid outages and curtailment, new shading, customer shutdowns, monitoring-data gaps and other exclusions. A generation guarantee does not guarantee electricity prices, customer savings, payback or freedom from fire. This option is under development and is not currently offered for purchase.
Monthly installation finance payment
£0
Monthly care · year one
£83.33
Average regular monthly benefit after payment
£992
25-year benefit incl. finance interest
£366,768
Upfront cash: £41,368. Finance interest cost: £0. Capital costs are counted once. Care is payable monthly even with a cash installation and is already deducted from the monthly benefit. Excludes arrangement fees and other tax effects. Any estimated AIA benefit is shown separately from regular monthly savings. Replacement allowances remain payable in years 13 (battery) and 15 (PV inverter), regardless of maintenance selection.
QUALITY YOU CAN CHECK
Fire risk reduction, backed by evidence
We ask installers for traceable connector and tooling records, agreed connector containment, electrical test results, labelled isolation and a documented emergency handover. Ongoing Care includes the agreed accessible safety checks and monitoring reviews.
Agree the final project standard and scope before contracting. Site-made connector enclosures and supported arc-fault detection serve different functions. Specialist alarm interfaces, thermal surveys, access and remedial works need an agreed scope and price. Record authorised access owners and secure-handover references; never passwords or alarm PINs in reports. This approach reduces risk; it is not a guarantee against fire.
Electrical extras and costs to confirm
Include additional site costs as they become clear. These allowances update the selected investment, finance and payback.
For additional switchgear, distribution-board or protection upgrades beyond the base installation scope. Confirm the exact electrical design. £0 means not separately costed, not necessarily unnecessary.
Reallocate existing allowances to avoid counting the same work twice. The combined access and switchgear credits cannot exceed Other provisional site extras.
Other provisional site extras £2,068 included in the installation price: automatic 5% of £41,368 net installation contract value excluding VAT. This is a provisional allowance, not a further fee. Customer-arranged access paid directly is excluded from the percentage base; access and switchgear credits only reallocate the allowance.
Net deal value means the installation contract price excluding VAT, including this provision and any selected installation extras. Customer-arranged access paid directly is excluded. This allowance is already included in the price; credits reallocate it and cannot be counted twice. Enter a fixed amount to override the automatic percentage.
Additional switchgear allowance £0, less £0 already in general site extras = £0 added to installation and payback. Switchgear scope and cost to confirm at survey. Other survey costs to confirm: electrical runs/remedials, DNO/network/export controls and metering, roof/structural/asbestos works, permits/consents, access, insurer/fire requirements, VAT/funding fees and contingency. No separate amount is added for unpriced items.
Emergency power for essential circuits
Keep selected communications, CCTV, lighting and sockets supplied during a power cut, within the agreed battery and load limits.
Explore the EPS upgrade and guide price
A compatible Fox P3-50-Plus has an EPS output built in. This allowance covers the additional agreed essential-circuit installation, switching, protection, labelling, testing and handover. Battery and inverter purchase are already separate project items and are not included again.
Guide price £1,995 + VAT, subject to full site survey. A straightforward upgrade during installation may be £1,500–£2,500 + VAT. These are our estimating allowances, not verified market averages or fixed offers. Complex circuits, long runs, major board alterations, additional battery capacity or a separate UPS require a separate quote. Check UK equipment approval and compatibility before specifying.
Holding battery charge for outages can reduce energy savings. The figures include the selected upgrade cost but do not yet simulate an emergency reserve or income saved during outages. Confirm the reserve and revise the forecast at technical review.
Additional work only. Remove any overlapping switchgear or general allowance so the same work is counted once.
EPS not selected; no upgrade cost included. Emergency power for agreed essential circuits only, subject to full site survey, equipment compatibility and final quotation. Battery/inverter not charged twice. Emergency reserve and outage-value savings are not simulated; reserving charge may reduce the energy savings shown. Avoid overlapping switchgear or general extras.
Potential additional costs to check at survey
Agree what is included, who pays and the quoted allowance before the final installation contract. Items below are review points, not automatic added charges.
Switchgear has its own allowance above. Access has its own controls below. Other agreed costs can be entered in Other provisional site extras; avoid counting the same work twice.
Check
What may need allowing for
Electrical works
Main switchgear / DB capacity, earthing or existing defects, long AC/DC cable runs, containment, trenching, fire-stopping and shutdown or out-of-hours working. Include board work only once under the switchgear or general allowance.
Grid connection and export
DNO assessment / connection charges, network works, export limitation equipment, protection studies or witnessing, metering and supplier changes where required. Third-party costs are separate from our conditional £495 application-management fee. Export restrictions can also reduce income.
Roof and structure
Structural calculations, load testing, roof repairs / rooflights, asbestos surveys or specialist works, fragile-roof protection, mounting changes and roof-warranty requirements.
Access and logistics
Scaffold duration / alterations, edge protection, loading platform, crane / MEWP, deliveries, permits and safe maintenance access. Use the access allowances below; do not add the same work again.
Permissions and specialist design
Landlord / freeholder consent, planning or specialist reports where needed, insurer requirements, fire strategy, lightning protection and battery location / ventilation or enclosure works. Routine agreed installation project management, RAMS and H&S are already included.
Operating costs
Monthly care even with a cash installation; cleaning access, internet / monitoring subscriptions, insurance changes and uncovered call-outs / repairs. Routine cleaning is included in Care and Enhanced Care; special cleaning and access need agreement.
Later-life costs
Battery year-13 and inverter year-15 replacement allowances are already modelled. Also review other component repairs and end-of-life removal / recycling; these have no separate allowance unless entered.
Emergency power / EPS
Optional essential-circuit backup. Use the separate EPS control above to include an editable £1,995 + VAT planning allowance with battery solutions, subject to full site survey. Confirm switching, circuit alterations, battery compatibility and reserve; avoid overlap with switchgear or other extras. No whole-building backup or guaranteed duration is assumed.
VAT, funding and risk
Headline prices exclude VAT; check recoverability and timing, finance arrangement fees and any contingency. These are not automatically added. The £495 service-fee credit must not be counted as a second installation cost when credited.
We will review safe roof access, loading and future maintenance with you at the technical survey. You can ask Watt Next to manage the agreed access works, or arrange them through your own competent contractor. Safe access still needs to be suitable for the work.
Permanent rail and a suitable access route can support future maintenance and may avoid repeated temporary access work. The right solution depends on the roof and site assessment; a ladder is not automatically suitable. Required installation safety measures are not optional.
Plan once for installation and future care
Where suitable, hire the loading platform for the initial installation and install permanent perimeter rail with a separately assessed access chamber, hatch, stair or ladder route. This can reduce repeat temporary-access work for future cleaning and checks. A loading platform is not itself permanent access or perimeter fall protection.
You may choose Watt Next Care or arrange competent maintenance and cleaning yourself. Permanent rail does not make every roof safe: assess fragile surfaces, rooflights, walkways and electrical risks. Electrical testing and repairs need suitably competent people. Agree inspection and maintenance of the access system, including any specialist inspection fees; these are not automatically included in Care.
How transparent is the rail price?
The starting allowance is £150 per metre excluding VAT, an editable planning estimate, not a verified UK average or a fixed installation quote. Published supplier guides checked 22 October 2026 were around £94–£97/m for components; installation, corners, gates, delivery/lifting, design and handover can add cost. Roof type, height, wind exposure and the selected system affect the quotation.
Access costs to confirm at the technical survey. The £22,300 currently entered below is not yet included in the headline price or payback.
Review access choices and their effect on price and payback
Defaults to 5% of the installation quote, recalculated as the system changes. Enter your own amount to override it. The credit reallocates existing site extras; it is capped by the available allowance and access costs, so it cannot create an extra discount.
Automatic: 5% of £41,368. Applied credit £0 (capped by existing extras / access cost); not applied until access allowances are included.
Installation contract allowance: £41,368. Total project investment for payback: £41,368.
Allowances exclude VAT and need a site-specific quotation. A zero rail length or access-route cost means not yet costed, not free. Rail suitability, fixings, roof structure, access, scaffold design, MEWPs / lifting and inspection arrangements require review. Repeat temporary access for later maintenance is separately quoted unless included in the agreed maintenance scope. No automatic maintenance saving is assumed.
Included in the agreed installation scope
Installation project management, site-specific RAMS and H&S planning are included. MCS certification is included where applicable and eligible, through an appropriately certified installer; confirm the final certification scope before contracting. Physical access works and specialist reports are separately itemised where required.
Engineering and financial checks
Three-site calculation test · passed 8 October 2026
Synthetic site
Sweet Spot
Year-one net operating benefit
Cumulative payback
Site A
50 kWp / 0 kWh
£10,245
5 years
Site B
140 kWp / 0 kWh
£30,559
4 years
Site C
50 kWp / 0 kWh
£5,768
11 years
Historical test assumptions: full overnight charging, midnight–07:00, Care maintenance, 2.5% annual energy price growth, cash purchase; prices exclude VAT and tax benefits. A: 90,000 kWh/year, 90% daytime, £0.25/£0.24 import, £0.05 export, 50 kWp roof. B: 250,000 kWh/year, 60% daytime, £0.29/£0.07 import, £0.05 export, 250 kWp roof. C: 160,000 kWh/year, 30% daytime, £0.18/£0.17 import, £0.01 export, 600 kWp roof. Extra costs: £5,000 / £15,000 / £30,000 respectively. Not real buildings or verified quotations.
Passed: annual/monthly reconciliation, exact assumed PV yield, energy balance, equipment search limits, package cost ordering, no-investment case, cash and loan arithmetic, deposit cap, and charging loss threshold. These checks validate calculation behaviour, not site performance.
Green — financial model result only
Amber — synthetic consumption profile; measured data has not been imported.
Amber — tariff verification outstanding
Amber — technical survey outstanding
✓ PV and battery energy conservation residual: 0.0000 kWh
✓ PV generation plausible for chosen yield: 47025 kWh
✓ No negative physical energy quantities: Checked
✓ Charging tariff counted as a cost: £0
✓ Annual O&M included: £1,000
✓ 25-year inverter and battery replacement allowance: Included in cash forecast
The simulation enforces battery state-of-charge limits, charge/discharge power, energy conservation, and charging costs. It uses a 365-day synthetic year, not measured site load. Stored battery charge carries between days. The 25-year forecast applies a simplified 0.5% annual reduction to energy benefit, 2.5% O&M inflation and a 5% discount rate. Battery ageing and tariff-hour changes are not simulated.
Happy with the direction? Start with the grid connection.
Your survey and application: Watt Next
Appoint Watt Next directly for the agreed survey, feasibility report and DNO application management. We apply on your behalf with a signed Letter of Authority; the customer/site remains the connection party. Technical information requires competent designer review.
The chosen installer approves the final technical design, specification and price, then contracts with and invoices you separately. Watt Next’s proposed installer-funded remuneration is 10% of the agreed installation contract value excluding VAT, included within that price, subject to a written installer agreement. The £495 service fee actually paid is offset against our total agreed remuneration if installation proceeds; the installer credits the same amount against your installation invoice. It is counted once.
No installation deposit is due at the survey/application stage. Our 5% provisional site-cost allowance is a project budget, separate from the 10% remuneration. This tool does not add another 10% to the displayed price or guarantee an installer will accept it. Installer approval of scope, price and fee is required before a binding installation quotation.
Take a smaller first step: authorise the DNO application and a full survey report, with no installation commitment.
1 · Agree the scopeWritten authority and clear connection criteria
Confirm acceptable capacity, export conditions, network costs and timing.
2 · Receive the findings£495 per agreed DNO application
Payable only when the documented outcome meets the agreed criteria, even if you then do not install. If you install, the £495 already paid is credited against the installation invoice. Full survey report included; no separate survey charge.
3 · Decide on installationFinal proposal before your deposit
Complete technical checks, confirm the scope and price, then sign the separate installation contract before paying the agreed deposit.
Roof evidence suits the site: use safe access where available, or a drone where required and safe. You receive a dated before-work recording and, if installation proceeds, an after-installation recording at handover.
No acceptable outcome means no service fee. Additional DNO charges, network works and specialist reports require separate prior approval; any approved third-party charges may remain payable even if the project does not proceed. This is an application-management fee, not a universal DNO tariff. The £495 fee is paid separately at the acceptable-outcome stage, then credited against the installation invoice if you proceed. The illustrated installation price is not increased to fund the credit; the fee is not charged twice.
Preview a WhatsApp summary or prepare an email draft with the proposal attached in the survey builder. Direct email sending is awaiting connection. Check the customer details before sharing.
Opens your survey/report builder with the selected calculator figures as an unsaved draft. Enter the address and confirm the terms there; nothing is submitted, signed or charged here.
Before issuing a quotation
Confirm electricity consumption and tariff periods, roof capacity and condition, shading, DNO/export permissions, electrical distribution, fire strategy, access and lifting requirements, structural survey, metering, and supplier O&M and replacement terms. Tax treatment and financing require separate advice.
Autopilot's recommendation is a screening result, not a guarantee of savings or a design certificate. Project prices exclude VAT; any estimated tax benefit is illustrated separately. Indicative cost assumptions only.
