Calculators

Each calculator answers one concrete question from your own inputs rather than from national averages. They are built for one country at a time, because a solar answer is made of local irradiance, local consumption habits, local prices and local rules — so the country comes first here, before the question.

Germany

The German calculators run the same simulation as the full stromFit analysis. The two balcony solar calculators work on real systems that can actually be bought in Germany; the energy sharing calculator works on the system you already have.

• Balcony solar payback calculator

  How long a balcony solar system takes to pay for itself in your household, from your postcode, your orientation and when you are actually at home.

• Balcony solar battery calculator

  Whether adding a battery pays for itself on top of the panels – judged on what the battery adds, and reported plainly when the answer is no.

• Sell solar power to neighbours

  Got solar panels? How much you could earn by selling your excess power to neighbours or a local business under the 2026 rules – after every cost.

Great Britain

A separate territory, not a translation. Plug-in solar became lawful in Great Britain on 27 August 2026, and almost nothing about the German answer carries over: different rules, a different register, different prices, and no entitlement to be paid for what you export. There is no British calculator here yet, and the reason is written down rather than hidden — we have no verified British product catalogue and no British household load model, and a saving computed without them would be a German answer wearing a pound sign.

What does exist is the part we can substantiate:

• Plug-in solar in the UK

  What changed on 27 August 2026, which rules apply where, whether anyone pays you for what you export, and the primary source for each — with the date it was read.

• The GB plug-in solar register

  Every device on the ENA Type Test Register, the status the register records for it, and why Northern Ireland is a separate question.

• What a UKSOL kit costs

  Prices read off the manufacturer's store and its official reseller, why the same kit appears twice, and why we will not quote you a saving yet.

Other sections

• Guides
• Comparisons
• Methodology – how stromFit calculates