Coverage
What works where
Most of this site is not country-specific at all. How much an array produces, what shade costs, how fast panels degrade, whether a battery lasts: none of that is regulated and none of it changes at a border. What is national is the price you are paid for exported electricity, and that is the only part with a map attached.
Available everywhere
Yield estimates and every guide on how solar behaves
The estimate tool covers 38 locations across six continents, handles both hemispheres, and takes your electricity prices in your own currency. Thirteen of the nineteen guides have no geography in them at all.
Export rules, country by country
A rate per exported unit, an annual netting arrangement and an hourly avoided-cost price are three different calculations. The full calculator implements one of them.
Great Britain
Calculator availableSmart Export Guarantee
Larger suppliers must offer an export tariff above zero. Each supplier sets its own rate, so what you are paid is a commercial decision rather than a regulated figure.
Netherlands
Guide onlySalderingsregeling, ending 1 January 2027
Export is netted against import across the year until 31 December 2026. From 1 January 2027 suppliers pay a rate they set themselves, with a statutory floor of 50% of the bare supply price until 2030.
What the engine would need first
- Annual netting of export against import, which is how the rules work until 31 December 2026
- The post-2027 supplier-set payment and its 50% statutory floor
- Terugleverkosten, the separate feed-in charges suppliers already levy
- Dutch energy tax and the VAT treatment that sits on top of both
United States
Guide onlySet state by state, with no federal rule
Retail electricity is regulated by state commissions rather than federally, and municipal utilities and rural cooperatives are often outside even that. Almost every arrangement is one of three shapes, and which one covers you decides whether an exported unit is worth the same as one you buy or a fraction of it.
California is modelled in the guides as a worked example, because the CPUC published the arithmetic when it moved to net billing in 2023. It is an illustration of the mechanism rather than a description of any other state.
What the engine would need first
- Fifty state regimes, plus the municipal utilities and cooperatives that sit outside them
- Per-utility tariff sheets, where the detail that decides a bill actually lives
- Rollover and annual true-up rules, which differ between utilities in the same state
- Non-bypassable and fixed charges, the part of a bill solar cannot reduce
- Legacy terms for systems interconnected under an earlier regime
Why we will not give you a rough number instead
Applying Great Britain’s arithmetic to another country’s rules produces a figure with the right units, the right order of magnitude and no relationship to what the household would actually be paid. Nobody reading it could tell, which is what makes it worse than no figure at all. The estimate tool avoids the problem entirely by asking you for your own rates instead of assuming them.
The guides for unmodelled markets carry the rules, the dates they were checked and the primary source they came from. That is genuinely useful and it is honest about being a description rather than a calculation.
If you want a market added, the constraint is engine work rather than interest. How the calculation works sets out what that involves.