Balcony solar calculator: when does plug-in solar pay off?

Usually yes, if the panels get direct sun and someone uses power during the day. A typical 800 W kit costs a few hundred euros or pounds and offsets your base load: fridge, router, standby devices and home office. At an electricity price of around 30 to 40 cents per kWh, many kits pay for themselves in three to six years and then keep saving for 20 years or more. Shade, a north-facing spot or a very low daytime load stretch that out. Enter your own numbers above to see your result.

In Germany, roughly 500 to 800 kWh a year, depending on direction, tilt and shade. Panels hung vertically on a railing make about a quarter less than panels tilted at 30 degrees. What counts for payback is how much of that you use yourself. Power you don't use flows into the grid, usually without payment. The calculator splits your yield into used directly, stored and exported.

In Germany, yes: up to 800 W inverter output and 2,000 Wp of panels, registered in the Marktstammdatenregister. In the UK, certified plug-in kits up to 800 W are legal from 27 August 2026; you notify your network operator with a G98 form. In the US, Utah allows plug-in systems under 1,200 W since 2025, and Maine, Colorado and other states are adding rules, so check with your utility first. Elsewhere, ask your grid operator before you plug in.

Usually not. A battery often costs more than the kit itself and only raises how much of your own power you use, not how much you produce. It can pay off when you have more panel power than the 800 W limit and use little electricity during the day, because then it shifts the surplus into the evening. Switch the battery on and off in the calculator to compare both payback times. The first UK rules for plug-in solar leave batteries out.

In Germany, since October 2024 a landlord or owners' association may only refuse in exceptional cases, but you still have to ask for permission first. In the UK, renters and leaseholders need permission from the landlord or freeholder. Because a plug-in kit plugs into a socket, you can take it with you when you move.

South gives the most yield. East or west produce about 15 to 20 percent less, but spread the power over the morning or evening, which often suits when people are at home. North-facing panels make little and rarely pay off. Enter your balcony's compass direction and tilt above; the calculator shows the yield as a percentage of an ideal south-facing panel.

It flows into the public grid. With a plug-in kit you usually get nothing for it, so a kit sized to your base load pays back faster than an oversized one. In the UK, plug-in systems don't automatically qualify for the Smart Export Guarantee at launch.

Panels typically last 25 years or more and lose a little output each year. The micro-inverter is the part most likely to fail, often after 10 to 15 years, and costs about 100 to 200 to replace. After the payback point, every year is profit.

Every payback figure is a model. Read your electricity meter and the inverter on the same day each month: that shows how much solar power you use yourself, how much you export and how your bill changes. TrackIt+ for Android logs meter readings offline, and its PV cockpit shows how far your system has really paid for itself, so you can compare reality with this calculator.