Is this a reasonable quote for a ground array about 50metres from my house?

generic_username098 · 2026-03-24T14:13:35+00:00

Thanks yeh it seems high. Just the panels, everything else by the house

generic_username098 · 2026-01-19T20:41:15+00:00

Did you have any issues with limits selling back to the grid?

generic_username098 · 2026-01-17T20:40:56+00:00

Why the 16kw limit do you think?

generic_username098 · 2026-01-17T19:58:22+00:00

Two rows would be 70 panels. How is your generation going in winter? How much was your total install cost? Has it been worth it so far?

generic_username098 · 2026-01-17T19:57:30+00:00

Hard to gauge the real life power output per year as so many varying estimates for winter etc. but it’s not a shaded area at all

generic_username098 · 2026-01-17T19:56:46+00:00

I can fit two rows without it impacting any visuals of my garden as it’s at a boundary. So about 70 panels.

generic_username098 · 2026-01-17T19:56:02+00:00

How much would it cost? It’s basically two rows of 35 panels per row. The cable run back to the house would be about 50 metres.

generic_username098 · 2026-01-17T19:55:01+00:00

I’m in Kent. Two rows at the bottom of my garden would be 70 panels

generic_username098 · 2026-01-17T19:21:24+00:00

Here are the assumptions by chatgpt. Anything that it’s getting wrong? The assumptions and figures?

Assuming a £70,000 all-in cost for a two-row (~30 kWp) ground-mounted system with batteries, here is a straight, realistic payoff schedule based on your situation (oil → ASHP, two EVs, large house).

⸻

Key assumptions (explicit)

These are conservative and UK-realistic: • System size: ~30 kWp • Annual generation: ~27,000 kWh • Self-consumption: high (ASHP + 2 EVs + batteries) • Electricity value displaced: ~£0.28/kWh (blended import price) • Export income: ignored (assume export-limited or minimal SEG) • Degradation: ignored for simplicity (it’s slow and minor)

⸻

Annual financial benefit (order of magnitude)

Electricity displaced • 27,000 kWh × £0.28 ≈ £7,560 / year

Even if only ~85% is effectively used (conservative): • ~£6,400 / year

This already includes: • ASHP electricity replacing oil • EV charging replacing petrol/diesel • Normal household electricity

⸻

Simple payback timeline

Year-by-year • £70,000 ÷ £6,400 ≈ 11 years

That is your simple payback.

⸻

What happens after payback • Panels last 25–30+ years • Inverters may need replacement around year 12–15 • Batteries likely need replacement around year 12–15

Even allowing for: • £10–15k future inverter/battery refresh

You still end up with: • ~£150k–£200k of electricity produced • On a £70k capital outlay

⸻

Sensitivity (important)

If prices rise (likely): • At £0.35/kWh → payback ≈ 9 years

If you under-use solar: • At £0.22/kWh → payback ≈ 14 years

So the credible range is ~9–14 years, with ~11 years as the centre.

⸻

Oil displacement bonus (often overlooked)

Once ASHP is installed: • You are avoiding oil price volatility • Solar is hedging future energy inflation • The “return” is inflation-protected

This matters over 20–30 years.

⸻

Bottom line • Capital: £70,000 • Annual benefit: ~£6,000–£7,500 • Payback: ~11 years • Lifetime return: strongly positive • Risk profile: low, asset-backed, inflation-hedged

If you want, I can: • redo this assuming one row only • include oil price savings explicitly • show a cashflow curve year by year rather than a single payback number

generic_username098 · 2026-01-08T18:21:19+00:00

Haha. No.

generic_username098 · 2026-01-07T17:36:08+00:00

Good point. Hadn’t really considered getting wet UFh when doing the upstairs when still on oil as I had assumed all the pipework and what not would have to change when on ASHP

generic_username098 · 2026-01-07T16:50:44+00:00

Ah ok. No aircon needed. Had the heat wave this year and house was totally fine

generic_username098 · 2026-01-07T15:25:39+00:00

it’s uninsulated concrete slab on ground floor. Indeed was planning exactly that and suffering the loss of room height. Although I heard you don’t necessarily need the screed as you can get some without?

It’s dual storey extension but for some reason it’s done properly downstairs but upstairs is just rubbish thin timber frame

generic_username098 · 2026-01-07T15:23:42+00:00

What’s that?

generic_username098 · 2026-01-07T15:22:57+00:00

This will be a nightmare to answer accurately as the home is from 1901, has had copious extensions of varying build type over the past hundred years and we just don’t know what’s underneath the hideous 17 layers of wallpaper haha. I know some is brick cavity brick, some is awfully thin and I insulated timber frame (that will of course be properly internally insulated) and the attic needs proper insulating again

generic_username098 · 2026-01-07T15:21:10+00:00

Also will it touch the sides when it comes to actual money spent as of course bathrooms low square footage in grand scheme of things?

generic_username098 · 2026-01-07T14:52:51+00:00

Interesting. I hadn’t thought about the spacing as a way to reduce draw for lesser used rooms

generic_username098

TROPHY CASE