Is Plug-in Solar Worth It?
Thinking about a plug-in or balcony solar kit? Work out how much electricity an 800 W kit would make where you live, how much of it your home would actually use, and how many years it takes to pay for itself.
No sign-up required. Free to use, with every formula shown on this page. Last reviewed October 2026.
Work out your payback
Plug-in Solar Payback
See how much a plug-in (balcony) solar kit would make, how much of it your home would actually use, and how many years it takes to pay for itself.
1 Your kit
The total of all the panels in the kit. The legal limit is 800 W from the inverter; panels can be bigger.
Complete 800 W kits mostly cost 450–600 in shops.
Battery included?2 Where it goes
Sets how much sunshine the panels get in a year.
Mounting3 Your home
Who's home during the day?Shown on your electricity bill.
Usually 0. Plug-in kits can't get export payments in the UK (no Smart Export Guarantee).
Pays for itself in
6,1 years
on a 500 € kit
Yearly saving
0
Yearly output
0 kWh
Gain over 25 years
0
Where the power goes
- Used at home 0 kWh 0%
- Sent to the grid 0 kWh 0%
Only the power you use at home saves you money, unless you're paid for what goes to the grid.
Rules where you live
Always check your tenancy, lease or building rules before fitting anything to a balcony or wall.
How it's worked out: yearly output = panel size × sunshine for your area (PVGIS, EU Joint Research Centre, best angle, 14% system losses) × mounting factor, reduced a little for panels above the 800 W inverter limit. Share used at home: 30%, 45% or 60% by daytime use, plus 10 points for upright or east/west panels; a battery adds about 60% of what would otherwise go to the grid (up to 90%). Saving = power used at home × electricity price + power sent to the grid × export payment. Payback = kit price ÷ yearly saving. The 25-year figure assumes output drops 0,5% a year and electricity prices stay as entered.
Estimates only. Actual output and savings vary with weather, shading, the exact angle of your panels, how much power you use during the day, and your tariff.
How it works
Three numbers decide whether a kit pays off
The calculator works out how much electricity the panels make, how much of it your home uses as it is made, and what that saves you. Only the power you use yourself cuts your bill, because plug-in kits are rarely paid anything for what goes to the grid. The sources and assumptions behind it are on our How we calculate page.
How much it makes
Panel size × the sunshine where you live × how the panels are mounted. An 800 W kit upright on a south-facing balcony in southern England makes about 570 kWh a year; tilted towards the sun, about 820 kWh.
How much you use
A kit makes most of its power around midday. If nobody is home, much of it flows out to the grid. Typically 30–60% is used at home, a bit more with upright or east/west panels, and more again with a battery.
What it saves
The power you use at home × your electricity price is the yearly saving. Divide the kit price by that saving and you have the payback time in years.
Examples
What does an 800 W kit save?
These examples use the calculator’s own formula. Where you live, how the panels are mounted and how much you are home during the day make the biggest difference.
Illustrative only, for an 800 W kit costing 500 £/€ with no battery and no payment for power sent to the grid. Electricity at £0.26 per kWh in England (Ofgem price cap, October–December 2026), 0,38 € in Germany and 0,22 € in Spain. Sunshine figures from PVGIS (EU Joint Research Centre). Actual output and savings vary with weather, shading, panel angle and how much power you use during the day.
Understand your result
How to get more out of a plug-in kit
The payback time is a starting point. A few changes can shorten it a lot, and some things are worth checking before you buy.
Use more power at midday
Run the washing machine, dishwasher or tumble dryer around the middle of the day, using their timers if you are out. Every kWh you use yourself instead of sending it to the grid adds to your saving.
Tilt the panels if you can
Panels hanging straight down from a railing make about 30% less than panels tilted towards the sun. Even a small frame that angles them helps, if your building allows it.
Buy a certified kit
Choose a complete kit from a known retailer. In Great Britain it must meet the government’s plug-in solar specification and appear on the G98 register, and you tell your network operator within 28 days.
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Common questions
Frequently asked questions about plug-in solar
Common questions about plug-in and balcony solar kits, what they save and the rules.
Is plug-in solar legal in the UK?
Yes, in Great Britain since 27 August 2026, for kits up to 800 VA that meet the government’s plug-in solar product specification. You plug the kit into a normal socket and tell your network operator with a short G98 form within 28 days. In Northern Ireland, check with NIE Networks before buying.
Is plug-in solar legal in Ireland and Spain?
Not yet in Ireland: connecting a kit still needs a registered electrician to sign an NC6 form, and rules for plug-in kits are expected later in 2026. Spain has no dedicated plug-in rules, so the general self-consumption rules apply, and in a block of flats you may need the community of owners’ agreement. Germany, France, Austria, Belgium and the Netherlands allow 800 W kits.
How much does an 800 W plug-in solar kit save?
In southern England, an 800 W kit upright on a south-facing balcony saves about £80 a year if someone is home some of the day, and about £95 if the panels are tilted towards the sun. In sunnier places such as central Spain it makes more power, but lower electricity prices mean savings of roughly 100–140 € a year.
Do I get paid for electricity I send to the grid?
Usually not. In the UK, plug-in kits cannot get Smart Export Guarantee payments, so any power you do not use flows to the grid for free. That is why the calculator only counts the share you use at home, unless you enter an export payment.
Does plug-in solar work on a north-facing balcony?
Not well. Panels hanging upright on a north-facing balcony make only about 12–20% of what the same panels make facing south at the best angle. Tilted at about 30° facing north they make roughly 55%. A north-facing balcony rarely pays back the cost of a kit.
Is a battery worth adding?
A battery stores power from the middle of the day for the evening, so more of what the panels make is used at home: often around 80% instead of 40–60%. But a battery adds to the price. Enter the full price of a kit with and without a battery in the calculator to see which pays back sooner.
Can I use plug-in solar in a rented flat?
Ask your landlord first, and check your lease or building rules. Fixing panels to a balcony or wall can need permission, and in a block of flats the community of owners or management company may have a say.
Are the results exact?
No. They are estimates. Actual output and savings vary with the weather, shading, the exact angle of your panels, how much power you use during the day and your tariff.