I don't have it at home, but we do on a scout hut that I somehow ended up being responsible for. In our case, we for a grant for all of it so, naturally, I think it's brilliant.

If you go down that route, find someone with a really good reputation to supply and install it. We made the mistake of going to one of the big energy companies, who just subbed the whole lot to whoever was cheapest. They managed (it's a flat roof) to point the panels in entirely the wrong direction, then wired them so that the inverter toasted itself one sunny day because it had too much coming in on one string.

Over the last couple of years, it's been a real godsend not having to worry about electricity prices. To a degree, that's worth something, as is knowing that you have back up in the event of a power cut. Assuming you have an EV tariff, you can also charge the batteries up at night once the car's full so your savings are much bigger.

My quote from a company with all the correct acreditations & memberships for 9 Panels + 5kw battery (mainly flat roof) with 25 yr warranty on invertors was £10,659 with estimated saving of £920/year (SE London/kent)

We have had 9 panels since the end of 2011. Our roof is not ideal as it faces SE, and the slope is rather shallow so it never gets maximum illumination, but in optimal conditions it can produce just over 2kW, or about 13 units on an ideal midsummer day. It cost about £10K to install and we were told to expect 10 years to pay it off, which was about right. No battery involved of course, but the big advantage is the protected tariff which we still get, meaning that as it is now 'paid for' we effectively get free leccy, as our providers pay back roughly what we pay them for grid leccy.

Today's FiT is now much less than ours, but so is the cost of installation. As an aside, last year was especially poor for sunlight. Our best years have totalled over 1700 units; last year less than 1500. Funnily enough, the last three weeks (early March) have had the best return yet for those weeks !

Edited by Andrew-T on 25/03/2025 at 18:39

I had a solar PV array installed back in Feb 2023. 17 400w panels alongside two 4.8 Kwh batteries. Peak power I’ve observed from my array is around 6.3Kw and I would regularly see >5Kw incoming when its bright out. Currently averaging about 5000 Kwh generation per year here in sunny Belfast, although the past two summers were anything but fantastic.

On a nice summers day, I could generate over 40 Kwh, conversely on a grey winter day, maybe only 0.5 Kwh. The ‘solar season’ runs from March thru September, 7 months where it performs brilliantly. Winter days are a bit hit or miss, but batteries can be charged on cheap overnight rates and then discharged to the house during the following day.

Note, Solar is most cost effective if you are a heavy electricity user and you use as much of your own generated power as possible. Our annual usage is about 5700 units of which about 60% is covered by solar. Based on some back of the envelope calcs, I reckon it “earns” me about £1200 per year in both offset energy use and export payments.

If you are looking to calculate rough figures for an array of your own, check out the resources on MCS website.

https://mcscertified.com/wp-content/uploads/2022/04/MGD-003-Solar-PV-Self-Consumption-Issue-2.0-Final.pdf

https://mcscertified.com/wp-content/uploads/2022/04/MGD003-LookupTables-FINAL.xlsx

https://mcscertified.com/wp-content/uploads/2019/08/Irradiance-Datasets.xlsx

The lookup tables gives you rough efficiency % based on annual generation and installed battery capacity based on whether you are at home all day, out all day or somewhere in between.

The irradience spreadsheet has entries for a number of major uk cities giving estimated annual units generated per KwP (peak power) of array (i.e. for a 5 KwP array, multiply the cell # by 5) for a given roof slope angle and orientation in degrees from south.

I used the map tool linked below to work out my roof orientation.

https://www.freemaptools.com/direction-projection.htm

You can get your roof angle by holding the edge of your phone against a rafter in your roof space with a measuring app.

Any questions, give me a shout below, I'll do my best to answer.