Calculators
Solar power system
Your city and consumption — and right away the system size, the number of panels, the roof space, output by month and by hour, the price and the payback.
What you get
- —panels
- —modules
- —roof space
- —output per year
- —of the solar used at home
- —of consumption from the sun
- —system price
- —savings per year
- —payback
By month, kWh
sunconsumption
Average day:
sunto the gridconsumptionbattery charge
Sun data:
What the calculation assumes
- Module — 475 W, about 1.8 × 1.13 m; 1 kW needs about 5 m² of roof with walkways.
- System losses — 14% (cables, inverter, dirt), the PVGIS default.
- Battery: 90% of the capacity is usable, round-trip efficiency 90%, power — half the capacity, but no less than 3 kW.
- In Russia the surplus is bought by the guaranteeing supplier (the regional retail supplier) at the wholesale price — about 3.3 ₽ per kWh in the European part; for Siberia and the Far East we have not found the price. The microgeneration limit is 50 kW of export for a home and 150 kW for a business (since 26.09.2026).
- A business in Russia pays under its own contract: enter the price per kWh from your bill, or the calculation will use the household tariff.
- In Vietnam up to 50% of output can be sold at 844.8 ₫ per kWh (2026); off by default — using it yourself pays more.
- The price is an installers’ benchmark; with a battery, a hybrid inverter is added. Delivery to remote regions is not included.
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.