Battery size calculator
What size home battery do you need?
A quick, plain-English starting point for sizing a home battery in Malta, based on how much electricity you use and how much backup you want.
Your household
What do you want to keep running in a power cut?
Your estimate
Suggested battery size
4.5–7 kWh
Size for your backup target (est.)
5 kWh
Energy needed for that backup (est.)
4.0 kWh
Your household uses roughly 11.0 kWh a day, and around 6.0 kWh of that falls outside solar hours. Without solar there is no surplus to store, so the range is based on the backup you asked for rather than on bill savings.
Without solar, a battery is mainly about resilience, not savings.
On the assumptions used here, a battery on its own has little or no economic benefit for a typical Maltese household bill — you would be storing electricity you have already paid for at the same rate. Its real value is keeping your home running during a power cut.
How common battery sizes compare
5 kWh
SuitableIn line with what your household would realistically use.
10 kWh
Larger than neededMore capacity than you would regularly use, so it costs more for little extra benefit.
15 kWh
Larger than neededMore capacity than you would regularly use, so it costs more for little extra benefit.
How we calculated this
- Daily use is your annual figure divided by 365. If you enter a bill instead, we convert it using a rough average of €0.13 per kWh.
- Evening and overnight use is assumed to be 70%, 55% or 40% of daily use for low, medium or high daytime use.
- If you give us your annual export we use that directly for daily surplus. Otherwise we estimate generation at 4.2 kWh per kWp per day (Malta annual average) and subtract your estimated daytime use — treat that as an estimate only.
- Backup estimates assume a steady average draw of 0.5 kW for essentials, 0.9 kW with comfort loads and 1.5 kW with one bedroom air conditioner. "Overnight" is treated as 10 hours.
- Usable capacity is assumed to be 90% of a battery's quoted (nominal) size, with 90% round-trip efficiency.
- This version doesn't estimate grants or euro savings. Results are estimates and actual performance depends on your consumption patterns, solar generation, the battery's usable capacity and efficiency, and how it is installed and configured.