Off-grid solar and battery sizing for Bergen
A 1 kW array in Bergen produces about 723 kWh a year — but that annual figure is not what sizes a system. December is, and in December the same array makes only 0.0 kWh a day, against 3.8 in June.
What do you need?
Battery bank
12.9 kWh
268 Ah at 48V
Solar array
115.93 kW
about 258 panels of 450W
Summer only
1.07 kW
if you only use it June-ish
Sizing by household
Year-round systems in Bergen, three days of autonomy, lithium.
| Use | Per day | Battery | Array | Panels |
|---|---|---|---|---|
| Weekend cabin LED lights, phone charging, a laptop, a small water pump |
1.0 kWh | 4.3 kWh | 38.64 kW | 86 |
| Basic off-grid living The above plus a small fridge and a few hours of television |
3.0 kWh | 12.9 kWh | 115.93 kW | 258 |
| Comfortable off-grid home Full-size fridge-freezer, washing machine, pumps, laptops |
6.0 kWh | 25.7 kWh | 231.85 kW | 516 |
| Everything except heating A normal household load, with heating and cooking on gas or wood |
10.0 kWh | 42.9 kWh | 386.42 kW | 859 |
Why December decides everything
Array needed to cover 3.0 kWh a day, month by month. The tallest bar is the one your system has to survive.
| Month | Yield per kW | Array needed | |
|---|---|---|---|
| January | 0.09 kWh/day | 43.27 kW | |
| February | 1.03 kWh/day | 3.97 kW | |
| March | 2.21 kWh/day | 1.85 kW | |
| April | 3.20 kWh/day | 1.27 kW | |
| May | 3.70 kWh/day | 1.10 kW | |
| June | 3.82 kWh/day | 1.07 kW | |
| July | 3.27 kWh/day | 1.25 kW | |
| August | 2.81 kWh/day | 1.45 kW | |
| September | 1.99 kWh/day | 2.05 kW | |
| October | 1.28 kWh/day | 3.19 kW | |
| November | 0.29 kWh/day | 14.07 kW | |
| December (worst) | 0.04 kWh/day | 115.93 kW |
What the numbers assume
- Battery capacity allows for inverter losses, round-trip efficiency, and a usable depth of discharge — 80% for lithium, 50% for lead-acid. Nameplate capacity is always larger than the energy you can actually use.
- Array size includes a 25% margin over the bare requirement. A system that exactly meets demand on an average day of December never recovers from a run of cloudy ones.
- Yield figures are measured, not modelled — PVGIS satellite and reanalysis data for 2005–2023, at the optimal angle for this location, with 14% system losses already deducted.
Other cities in Norway
Limitations
- No shading. Trees, terrain and buildings are not modelled and can dominate everything here.
- Nothing about heating. Electric heating or cooking multiplies these figures several times over. Off-grid systems almost always use gas or wood for heat.
- Batteries age. Capacity falls over years; installers commonly oversize to allow for it.
- This is an estimate, not a design. A real installation needs a survey, local electrical regulations, and someone accountable for the result.