Solar System Cost by Monthly kWh Usage: 500, 1000, 1500 & 2000 kWh
The quick answer: solar cost by monthly kWh usage
The fastest way to size a solar system is to start from your electricity bill, not your roof. Find your average monthly usage in kilowatt-hours (kWh) — it's on every bill and in your online energy account — and read across to the system size, panel count and cost.
As a rule of thumb for a home in Hertfordshire, North London or the wider South East: a UK home using 1,000 kWh per month needs roughly a 5.3 kWp system (about 11 Aiko 485W panels) costing around £8,500–£10,000 fitted, and generating roughly 4,800 kWh a year. A 500 kWh/month home needs about a 3.5 kWp system (8 panels, ~£5,500–£6,800); a 1,500 kWh/month home needs about 7.3 kWp (15 panels, ~£11,500–£13,500); and a 2,000 kWh/month home needs about 9.2 kWp (19 panels, ~£14,000–£16,500).
Those figures are real 2026 installed prices for the systems we fit — turnkey, MCS-certified, scaffolding and VAT included — not US ballparks. A quick honesty note before the table: solar doesn't replace 100% of your usage. A correctly sized system typically offsets 50–70% of your annual bill on its own, and 70–90% once you add a battery to shift daytime generation into the evening. The table below sizes each system so its annual generation broadly matches your annual usage — which is the sensible target — then the per-tier sections explain how much of that you'll actually self-consume.
| Monthly use (kWh) | Annual use (kWh) | System size (kWp) | Aiko 485W panels | Roof space (approx) | Install cost ex-VAT (2026)* | Est. annual generation | Indicative annual saving** |
|---|---|---|---|---|---|---|---|
| 500 | 6,000 | 3.5 kWp | 8 | ~16 m² | £5,500–£6,800 | ~3,100 kWh | £550–£750 |
| 750 | 9,000 | 4.4 kWp | 9 | ~18 m² | £6,800–£8,200 | ~3,950 kWh | £700–£950 |
| 1,000 | 12,000 | 5.3 kWp | 11 | ~22 m² | £8,500–£10,000 | ~4,800 kWh | £900–£1,200 |
| 1,250 | 15,000 | 6.3 kWp | 13 | ~26 m² | £9,800–£11,500 | ~5,650 kWh | £1,050–£1,400 |
| 1,500 | 18,000 | 7.3 kWp | 15 | ~30 m² | £11,500–£13,500 | ~6,550 kWh | £1,250–£1,650 |
| 2,000 | 24,000 | 9.2 kWp | 19 | ~38 m² | £14,000–£16,500 | ~8,250 kWh | £1,550–£2,100 |
| *Prices are zero-rated for VAT until 31 March 2027 under the energy-saving materials relief, so ex-VAT and inc-VAT are currently the same — see the VAT section. **Saving assumes a typical 50–70% self-consumption split plus SEG export earnings; a battery pushes this higher. Generation uses ~900 kWh per kWp per year for a well-oriented South-East roof. |
How we did the maths (and why UK figures matter)
A lot of "how many panels for X kWh" pages online are written for the United States, where homes are bigger, the sun is stronger and a panel produces far more per year. Copying those numbers into a UK quote is how people end up wildly under- or over-sized. Here's the UK reality we use on every Sola design.
Generation per kWp: In the South East — St Albans, Watford, Hemel Hempstead, the North London boroughs — a well-oriented, unshaded roof produces roughly 900 kWh per kWp installed per year. South-facing at ~35° can nudge above that; east-west splits or some shading come in a little under. We deliberately design to a sensible real-world figure rather than a lab-perfect one, so the savings you see in year one match the savings on the page.
Panel maths: We fit Aiko 485W all-black panels (ABC monocrystalline, ~25% efficiency). To get the panel count we divide system size by 0.485 kW and round to a whole panel — so a 5.3 kWp system is 11 panels (11 × 485W = 5.335 kWp). Each panel occupies roughly 2 m² of roof, which is where the roof-space column comes from.
Why not just size generation to equal usage? Because you can't use every kWh as it's made. Solar generates in the daytime; a lot of household demand is mornings and evenings. Without a battery you'll directly use 50–70% of what you generate and export the rest. That's not wasted — you're paid for exports via SEG — but it's why a battery changes the economics, and why we size to annual generation ≈ annual usage as a balanced starting point rather than chasing 100% offset.
| Factor | UK / South-East figure we use | Why it matters |
|---|---|---|
| Annual yield | ~900 kWh per kWp/year | Realistic for Herts & North London; US pages assume far more |
| Panel | Aiko 485W all-black | Fewer panels for the same kWp vs older 400W panels |
| Roof per panel | ~2 m² | Lets you sanity-check the design against your actual roof |
| Self-consumption | 50–70% (no battery) | Solar is daytime; demand isn't — this is the honest number |
| Self-consumption | 70–90% (with battery) | Battery shifts daytime solar into the evening |
500 kWh per month — small home, careful user
A home using around 500 kWh a month (~6,000 kWh a year) is typically a one- or two-person household, a flat with a roof allocation, or an energy-conscious family already on top of their bills. This is the lower end of UK domestic demand.
The maths: 6,000 kWh ÷ 900 = ~6.7 kWp would be needed to fully match annual usage, but for a smaller home that's often more roof and outlay than makes sense, and self-consumption would be low. We usually recommend a 3.5 kWp system (8 × Aiko 485W) here, generating ~3,100 kWh/year. That covers most of your daytime base load and a good chunk of your annual bill.
Cost: roughly £5,500–£6,800 fitted in 2026, fully installed with scaffolding and MCS certification.
Battery note: at this usage a smaller battery (around 5 kWh) is often the sweet spot — enough to bank surplus and cover the evening without paying for capacity you'll never cycle. Is 500 kWh/month worth solar? Often yes — payback typically lands around 9–12 years and the system keeps earning long after — but it's the tier where a quick calculator check pays off most, because the answer depends heavily on how much of your usage is daytime.
1,000 kWh per month — the typical UK family home
This is the most common tier we quote. A household using ~1,000 kWh a month (12,000 kWh a year) is a typical three- to four-bedroom family home — a couple of EVs charging occasionally, a heat pump in some cases, dishwasher, dryer and the usual evening peak.
The maths: 12,000 kWh ÷ 900 ≈ 13 kWp to fully match usage, but most family roofs and budgets land on a 5.3 kWp system (11 × Aiko 485W), generating ~4,800 kWh/year and offsetting a large share of daytime demand. If you have the roof and the appetite, going to 6.3 kWp (13 panels) captures more, especially with a battery and an EV.
Cost: roughly £8,500–£10,000 fitted in 2026.
Battery note: this is the tier where a 10–13.5 kWh battery (we fit SigEnergy and Tesla Powerwall) genuinely transforms the numbers — self-consumption jumps from ~60% to 80%+, and you can charge cheaply overnight on an off-peak tariff and run the house on it through the peak. Most of our 1,000 kWh/month customers add storage and see payback in the 8–11 year range.
1,500 kWh per month — large home, EV or heat pump
A home pulling ~1,500 kWh a month (18,000 kWh a year) is usually a larger four- or five-bedroom property, often with an EV doing real mileage, electric heating or a heat pump, and a hot tub or home office load. Electrified heating and transport push a lot of homes into this band.
The maths: we'd typically design a 7.3 kWp system (15 × Aiko 485W), generating ~6,550 kWh/year. On a generous south or east-west roof you can go larger; the limit is usually roof area and your DNO connection (systems above ~3.68 kW per phase need DNO approval, which we handle).
Cost: roughly £11,500–£13,500 fitted in 2026.
Battery note: at this usage a battery isn't optional if you want strong returns — a 13.5 kWh+ unit, or a stackable SigEnergy setup, lets you self-consume the bulk of generation and load-shift cheap overnight power for the EV and heating. With the right tariff, homes at this tier often see the fastest payback of any band, because every kWh you self-generate displaces electricity you'd otherwise buy at peak rates.
2,000 kWh per month — high-consumption household
A home using ~2,000 kWh a month (24,000 kWh a year) is genuinely high-consumption — typically a large property with a heat pump, two EVs, a pool or extensive electric heating. This is where US sizing pages go most wrong: you'll see claims that 2,000 kWh/month needs a tiny 3–4 kW system, which is simply false for the UK.
The maths: 24,000 kWh ÷ 900 ≈ 27 kWp to fully match usage — more than most domestic roofs can hold. Realistically we design the largest system the roof and DNO allow, commonly a 9.2 kWp array (19 × Aiko 485W, ~38 m²) generating ~8,250 kWh/year, and pair it with a substantial battery to make the most of it. Larger arrays are possible on big or multi-aspect roofs.
Cost: roughly £14,000–£16,500 fitted in 2026 for a 9.2 kWp system; larger arrays and bigger batteries scale from there.
Battery note: at this consumption, storage and tariff strategy matter more than squeezing in extra panels. A large or stacked battery on a time-of-use tariff means you self-generate in summer and load-shift cheap overnight power in winter. We'll model the whole picture — array, battery and tariff — rather than just selling you the biggest roof.
0% VAT and SEG export earnings (dated)
Two things improve the numbers above beyond the install price itself, and both come with dates worth pinning down.
0% VAT (zero-rating): Domestic solar panels and home battery storage are currently zero-rated for VAT in Great Britain under the energy-saving materials (ESM) relief. This relief runs until 31 March 2027, after which — under current policy — the rate is set to return to 5%. (Standalone home batteries were brought into the 0% relief from 1 February 2024.) That's why the ex-VAT and inc-VAT columns are identical today. Always confirm the position at the point of quote, as government policy can change.
SEG export earnings: The Smart Export Guarantee (SEG) pays you for surplus electricity you export to the grid. Every licensed supplier of a certain size must offer an SEG tariff, but the rates vary by supplier and change regularly — at the time of writing competitive tariffs sit in the region of 12–15p per kWh exported, but some are lower and a few are higher. We can't promise a specific SEG rate because it depends on the supplier you choose, so treat export income as a real but variable top-up rather than a fixed figure. For the export side of the picture, our SEG calculator gives a live estimate based on your chosen tariff.
Net effect: between zero-rated VAT today and SEG income, the effective cost and payback of every tier above are better than the headline install price suggests — but check both figures at the time you buy, because both have moving parts.
Get an exact figure for your home
The table gives you an accurate starting bracket, but your real number depends on three things a generic table can't see: your roof orientation and shading, how much of your usage is daytime, and whether you add a battery. Two homes on the same 1,000 kWh/month can land £2,000 apart on payback for those reasons alone.
The fastest way to tighten the estimate is our tools. Use the solar ROI calculator for a payback and 25-year return figure, the system calculator to confirm how many panels for your monthly kWh usage, and the SEG calculator to estimate export income on your chosen tariff. Then, when you want it nailed down, we'll send a designer to look at the actual roof.
We're an MCS-certified installer based in St Albans, covering Hertfordshire, North London and the Bucks fringe, with 700+ installations behind us. A real survey and quote is free and there's no obligation — call 0800 470 0922 or request a quote and we'll give you a like-for-like design and price against the brackets on this page.
Frequently Asked Questions
How many solar panels do I need for 1,000 kWh per month in the UK?
For a typical UK home in the South East using 1,000 kWh a month (12,000 kWh a year), we usually recommend around 11 Aiko 485W panels — a 5.3 kWp system generating roughly 4,800 kWh a year. That offsets a large share of your daytime usage; adding a battery lets you self-consume 80%+ of what you generate. Roof orientation and shading can move the number up or down, so a quick check with our calculator or a free survey gives the exact figure.
What size solar system do I need for 2,000 kWh a month?
A 2,000 kWh/month home (24,000 kWh a year) is high-consumption. To fully match that usage you'd theoretically need around 27 kWp — more than most roofs can hold — so in practice we design the largest array the roof and your DNO allow, commonly around 9.2 kWp (19 Aiko 485W panels, ~38 m²) generating ~8,250 kWh a year, paired with a substantial battery. Beware US pages claiming 2,000 kWh/month needs a 3–4 kW system; that's wrong for the UK's lower sunlight.
How much does a 1,500 kWh per month solar system cost in 2026?
For 1,500 kWh a month (18,000 kWh a year) we typically design a 7.3 kWp system — around 15 Aiko 485W panels — costing roughly £11,500–£13,500 fitted in 2026, including scaffolding, MCS certification and (currently) zero-rated VAT. A battery is strongly recommended at this usage and adds to the cost but materially improves payback. A free survey gives an exact, roof-specific price.
Is 500 kWh per month enough to make solar worth it?
Often, yes. A 500 kWh/month home (6,000 kWh a year) suits a 3.5 kWp system (about 8 Aiko 485W panels, ~£5,500–£6,800 fitted), generating ~3,100 kWh a year. Payback typically lands around 9–12 years and the system keeps earning for 25+ years. It's the tier where the answer depends most on how much of your usage is in the daytime, so a quick calculator check is worth it before committing.
Why are your UK figures lower than American solar sizing charts?
Because UK roofs generate far less per panel than US ones. In the South East a well-oriented roof produces around 900 kWh per kWp per year; many US regions produce considerably more. American sizing charts therefore quote far smaller systems for the same usage — which leaves UK homes badly under-sized. Every number on this page uses real South-East yield and the Aiko 485W panels we actually fit.
Does a solar system cover 100% of my electricity usage?
No, and any installer who promises that should be questioned. Solar generates in the daytime, but a lot of household demand is mornings and evenings. Without a battery you'll directly self-consume around 50–70% of what you generate and export the rest (earning SEG income on it). Adding a battery pushes self-consumption to 80–90% by shifting daytime generation into the evening. We size systems so annual generation broadly matches annual usage as a balanced target.
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