What size battery do I need for plug-in solar?
A plug-in solar battery stores what your panels produce during the day and you do not use, so you can use it in the evening. How much you need depends on what you use after sunset: the background load of the house, the fridge, the router and the TV. We assume one night.
A typical setup
These devices at these power levels, for 24 hours without recharging. Adjust them to yours with the button below.
| Device | W | h/day | Wh/day |
|---|---|---|---|
| Standby and background load | 25 W | 24 | 600 Wh |
| Wi-Fi router | 12 W | 24 | 288 Wh |
| Fridge | 120 W | 24 | 864 Wh |
| TV | 80 W | 4 | 320 Wh |
| 4 × LED bulb | 9 W | 5 | 180 Wh |
- 2,252 Wh
- 3,180 Wh
Estimates based on typical consumption. They include inverter losses and a 20% reserve.
Recommended for this typical use
13 batteries meet everything
- EcoFlow STREAM AC 5000 – STREAM AC 5000£318/kWh£1,599.00
Plug-in solar batteries
5,024 Wh nominal for the 3,180 Wh you need (usable capacity not published)
- EcoFlow STREAM Ultra X Home Solar Battery – STREAM Ultra X (3.84kWh) / STREAM AC Pro (with 1 × FREE Parallel Cable)£330/kWh£1,899.00
Plug-in solar batteries
5,760 Wh nominal for the 3,180 Wh you need (usable capacity not published)
- EcoFlow STREAM Series Solar Battery STREAM 5000 – STREAM 5000£338/kWh£1,699.00
Plug-in solar batteries
5,024 Wh nominal for the 3,180 Wh you need (usable capacity not published)
- EcoFlow STREAM Ultra X Home Solar Battery – STREAM Ultra X (3.84kWh)£338/kWh£1,299.00
Plug-in solar batteries
3,840 Wh nominal for the 3,180 Wh you need (usable capacity not published)
- EcoFlow STREAM Ultra X Home Solar Battery – STREAM Ultra X (3.84kWh) / 2 × STREAM AC Pro (with 2 × FREE Parallel Cable)£338/kWh£2,599.00
Plug-in solar batteries
7,680 Wh nominal for the 3,180 Wh you need (usable capacity not published)
- EcoFlow STREAM Ultra X Home Solar Battery – STREAM Ultra X (3.84kWh) / 2 × STREAM AC Pro (with 1 × FREE Parallel Cable) + 4 × 500W Rigid Solar Panel£351/kWh£2,699.00
Plug-in solar kits with battery
7,680 Wh nominal for the 3,180 Wh you need (usable capacity not published)
Sorted by price per usable kWh among those that meet everything. Retailer commissions play no part. How we rank
How we calculate it
For each device we multiply its power by the hours per day and by the share of time it actually runs (a fridge only runs its compressor part of the time). We add them up and multiply by the days without recharging.
We divide that total by the inverter efficiency, which we take as 85%, and add a 20% reserve for cold weather, cell wear and not draining the battery completely. We compare it with the usable capacity the manufacturer declares, or the nominal one if it does not publish it, and we flag that.
Continuous output is the sum of what runs at the same time. Kitchen appliances and tools count one at a time, the biggest one. Surge power adds what the device with the highest start-up demand draws when it switches on.
We do not recommend batteries with more than three times the capacity you need, because you would pay for and carry capacity you will not use. If a battery is missing a figure we need, such as surge or solar input, we do not count it as a match.
Typical power figures for 230 V household power.
With a plug-in solar battery the grid still covers whatever the battery does not supply, so we do not require continuous output or surge power. Capacity is what matters.