Calculators
Payback
System, battery, price and tariff — and right away the savings per year, the payback period and the money over 25 years. You can enter your own price from an estimate.
What you get
- —yearly bill without the system
- —yearly bill with the system
- —savings in the first year
- —payback
- —total over 25 years
- —cost of your own kWh
- —output per year
- —of the solar used at home
Cumulative money over 25 years
cumulative money
What the calculation assumes
- Panels lose 0.5% of their power a year.
- The inverter is replaced in year 13 for 8% of the system price.
- Tariff growth is not adjusted for inflation; no discounting.
- Cost of your own kWh — the system price divided by its output over 25 years.
- Default tariff growth: Russia — 8% a year (+12.6% in 2025; +1.7% and +11.1–11.3% in 2026), Vietnam — 3%.
Why your numbers will differ
- The sun varies from year to year by about ±5%, and databases differ by a few more per cent. For cities east of 65° E and for Vietnam, PVGIS uses the ERA5 reanalysis — it is coarser than satellite data.
- The model does not see shade from trees, neighbouring houses and chimneys — only a site visit shows it.
- The average day of the month smooths out cloudy and sunny days: in real life a little less of your own sun gets used.
- The load profile is a typical one. If nobody is home during the day, less of your own sun gets used; if air conditioners and a kitchen run during the day, more.
- Prices are installers’ benchmarks on the date checked; your estimate depends on the roof, cables, switchboard and delivery.
- Tariffs change: in Russia they are indexed once a year; in Vietnam EVN revises the price by decision of the Ministry of Industry and Trade.
Sun and climate: PVGIS 5.3, Joint Research Centre of the European Commission — PVGIS © European Communities, 2001–2026.
Do the numbers add up?
Send them with a request — we’ll check on site and draw up an estimate.