Savings estimate
The sums, all of them.
Your bill, your roof, the panels and a battery or not. The estimate shows what the system might produce and save in a year and a payback range, and prints every assumption beside it, so you can see exactly what would change the answer.
Your estimate
Estimate, not a quote
- 4,700kWh a year generated by 5.2kWp on a south-facing roof
- £900a year, estimated: bills saved plus export paid
- 1,640kWh used at home instead of bought
- 3,050kWh exported to the grid
- 6 to 9 yearsestimated payback on a typical installed price of £6,840, 0% VAT
With a 10kWh battery the same estimate is £1,020 a year on £11,640, 9 to 14 years. See it with.
5.2kWp of panels is more than 3.68kW. Above 3.68kW of inverter capacity the network operator has to approve the system first (a G99 application, usually two to six weeks) or set an export limit. The alternative is a 3.68kW inverter, which clips a little at midday in summer. The survey recommends one; we handle either.
The assumptions
- Your bill
- £90 a month, £1,080 a year
- Standing charge taken off
- 55p a day
- Unit price you pay
- 27p a kWh
- So you use about
- 3,260 kWh a year
- Panel size
- 435W, 12 panels
- Yield for this roof
- 900 kWh a kWp a year
- Share used at home
- 35%, at most 80% of your use
- Export rate (Smart Export Guarantee)
- 15p a kWh
- Installed price
- £1,800 + £420 a panel
- VAT on home solar and batteries
- 0% until 31 March 2027
- Payback range
- the saving ±15%
This is an estimate on the assumptions above, not a quote, a promise or financial advice. Electricity and export prices change, your use will change, and shade, pitch and weather vary by roof and by year. Panel output also falls slowly with age. The survey replaces this with a design and expected generation under the MCS method for your roof.
How the estimate works
Four lines of arithmetic.
Your use
The bill, less the standing charge, divided by the unit price, gives the electricity you buy in a year.
The generation
The panels' total size times the yield for the way the roof faces, from typical figures for Bridgend county.
Used or exported
A share is used at home (more with a battery), never more than 80% of your own use; the rest is exported.
Saved and paid
Units used at home are saved at the unit price; exported units are paid at the export rate. Payback is the price over the saving, ±15%.
Questions about the estimate
Why is this only an estimate?
Because the answer depends on things only a survey sees (shade from a chimney at 3pm in March, the exact pitch, where the inverter can go) and things nobody knows (what electricity will cost in five years). We show the assumptions so you can judge the answer, not trust it.
Where do the yield figures come from?
Typical generation for Bridgend county at a 35° pitch with little shade: about 900kWh a year for each kWp facing south, 780 split east-west and 560 facing north. The survey uses the MCS method for your exact roof.
Can I use my own prices?
Not on this page, but the assumptions are printed so you can adjust in your head: if you pay 30p rather than 27p a unit, the home-use part of the saving rises by about a ninth.
A free survey, then a fixed price.
An hour on your roof and in your loft with our surveyor, then a written design with the expected generation and a fixed price that does not change unless the job does. Free within thirty miles of Pyle, and no obligation.