How much do solar panels cost in 2026?

In the UK (May 2026), a 4 kWp residential PV system costs £6,000–£8,500 fully installed; 6 kWp £8,500–£11,500; 8 kWp £11,000–£14,500. Battery storage adds £4,000–£7,000 for a 5–10 kWh unit. US prices: roughly $2.60–$3.30 per watt installed, so an 8 kW system is $20K–$26K before the 30% federal tax credit.

How many kWh will my panels produce?

As a rule, 1 kWp of south-facing panels in the UK produces ~850–1,000 kWh/year. In the US southwest it's 1,500–1,800 kWh/yr. Multiply your system size by your local kWh-per-kWp factor. East/west facing reduces output ~15%, shading or sub-optimal pitch can knock another 10–25% off.

What is the typical payback period?

At UK 2026 prices and 28p/kWh electricity: 6–10 years for a system without a battery, 7–12 years with a battery. The 25-year panel warranty means most systems generate free electricity for 13–18 years after payback. US payback with 30% tax credit and net metering is typically 7–9 years.

How does the Smart Export Guarantee (SEG) work?

In the UK, the SEG (replaced the Feed-in Tariff in 2020) requires licensed energy suppliers to pay you for excess solar exported to the grid. Rates vary by supplier — Octopus Outgoing Fixed offers ~15p/kWh as of 2026, EDF/E.ON typically 5–7p/kWh. You need a smart meter and an MCS-certified install to claim.

Should I add a battery?

Batteries store daytime solar for evening/night use, raising self-consumption from ~30% to 70%+. They also enable cheap-overnight grid charging on tariffs like Octopus Go (7p/kWh) for arbitrage. Financially, batteries add 1–3 years to payback but significantly raise lifetime ROI for households with high evening usage and EV charging.

☀️ Solar Panel Payback Calculator

Estimate residential solar PV cost, annual generation, savings, export income, payback period and 25-year ROI.

Region

System Size (kWp)

System Cost (installed)

Grant / Tax CreditUK: 0% VAT (already in price). US: enter 30% of cost.

Generation (kWh per kWp/year)

Self-Consumption (%)No battery ~30%; with battery 65–80%.

Annual Degradation (%)

Electricity Price (per kWh)

Export Tariff / SEG (per kWh)

⚠️ Estimate only. Real generation depends on roof orientation, pitch, shading, panel quality and weather. Inverter typically needs replacement at year 12–15 (~£800). Insurance and roof structure not modelled. Get 3 MCS / NABCEP-certified quotes before committing. Not financial advice.

Is Solar Worth It in 2026?

For most UK households with a south-facing roof, yes. Falling panel prices, rising electricity costs and a working Smart Export Guarantee mean payback periods are now 6–10 years — leaving 15+ years of effectively free electricity from a 25-year-warranted system. In the US, the 30% federal tax credit (Inflation Reduction Act, runs through 2032) keeps payback under 9 years in most states.

Costs (UK, May 2026 — fully installed, MCS certified)

4 kWp: £6,000–£8,500
6 kWp: £8,500–£11,500
8 kWp: £11,000–£14,500
10 kWp: £14,000–£18,000
+ Battery (5–10 kWh): £4,000–£7,000

VAT on residential solar is 0% in the UK (until March 2027). The cheap Chinese panel + cheap inverter end of the market starts ~£1,000/kWp installed; premium kit (LG, REC, SunPower, Tesla Powerwall) runs £1,800–£2,200/kWp.

How Much Will It Generate?

Rule of thumb for the UK: 1 kWp = ~850–1,000 kWh/year (south facing, 30–40° pitch, no shading). For a 6 kWp system that's 5,100–6,000 kWh/year — about half to two-thirds of a typical UK household's 4,000 kWh consumption.

Self-Consumption is the Multiplier

The economics swing massively on what fraction of generation you use yourself versus export:

Use it yourself: displaces 28p/kWh import — full retail value
Export to grid: earns SEG ~15p/kWh (Octopus Outgoing Fixed, 2026)

Without a battery, a typical household self-consumes ~30% of generation; with a battery, 65–80%. EV owners and heat-pump households can hit 50%+ even without a battery by shifting flexible loads to daylight.

Smart Export Guarantee (SEG) — Best Tariffs (UK May 2026)

Octopus Outgoing Fixed: 15p/kWh (best general fixed rate)
Octopus Outgoing Agile: half-hourly market price (averages ~12p, peaks at 30p+ in evenings)
Good Energy: ~5.5p/kWh
EDF Energy: ~5.6p/kWh
OVO: 4.0p/kWh

You can switch SEG provider independently of your import supplier — it's worth doing.

Things This Calculator Doesn't Model

Inverter replacement at year 12–15 (~£800)
Battery replacement at year 10–15 if fitted
Roof scaffolding / re-wiring if needed
Property value uplift (typically +1–4% for owner-occupier homes)
Income tax on SEG payments (HMRC currently treats domestic SEG as non-taxable for owner-occupiers)

⚠️

Important Note: Always get three quotes from MCS-certified installers (UK) or NABCEP-certified (US). Verify warranties cover panels (25 yr), inverter (10–12 yr) and workmanship (5–10 yr). Confirm your roof can take the load (roughly 18 kg/m²) and that your fuse board / consumer unit is compatible. DNO (UK) or utility (US) approval is required.

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