Are you curious about which capacity home battery best suits your household and solar panels? Then ask Shift to Solar for customised advice without obligation. On this page, we explain step by step how to calculate the right battery capacity, what to look out for when choosing a home battery and how to get the most out of your solar power.
Want to know which battery best suits your solar panels? Use this calculation tool to easily calculate the ideal storage capacity of your home battery.
Enter the number of solar panels you have and check that the standard power of 400 Wp per panel matches your installation. On this basis, you will immediately see how much energy you can store and which capacity is most suitable for your home.
From 2027 the net-metering scheme will be phased out. That means you will get less back for electricity you supply to the grid.
With a home battery you can store and use this power yourself. This way, you keep more benefit from your solar energy and become less dependent on energy suppliers.
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The capacity of a home battery determines how much electricity can be stored. This is expressed in kilowatt hour (kWh).
The larger the capacity, the more solar energy you can store for later use. This way, you also make use of your own solar energy at times when the sun is not shining.
Note that capacity is not about power. Power indicates how fast energy can be delivered, while capacity indicates how much energy is available when your solar panels are not generating power.
Calculating the right capacity does not have to be complicated. With a simple rule of thumb, you can quickly determine which battery fits your solar installation. You calculate 1 to 1.5 kWh of storage per kWp of solar power.
For example, do you have a solar installation of 6 kWp? Then a battery of about 6 to 9 kWh at. This way, the battery matches the amount of power you generate and you make the best use of your solar energy.
| Power of solar panels | Recommended battery capacity |
|---|---|
| 2 kWp | 2 - 3 kWh |
| 3 kWp | 3 - 5 kWh |
| 4 kWp | 4 - 6 kWh |
| 5 kWp | 5 - 8 kWh |
| 6 kWp | 6 - 9 kWh |
| 7 kWp | 7 - 10 kWh |
| 8 kWp | 8 - 12 kWh |
| 9 kWp | 9 - 13 kWh |
| 10 kWp | 10 - 15 kWh |
| 12 kWp | 12 - 18 kWh |
| 15 kWp | 15 - 22 kWh |
The ideal capacity depends on more than just the number of solar panels. Your consumption, peak times and future plans also play an important role. Below you can read which three factors are the most decisive.
How much power you consume determines the storage capacity you need. Large families or households with electric cars often benefit more from a larger battery to ensure sufficient energy remains available.
The more solar panels you have, the more power you can store. The battery capacity should match well with the total output of your installation to avoid over- or undercapacity.
Do you expect higher consumption due to, for example, a charging station, heat pump or electric heating? Then it is smart to take this into account now. That way, you avoid your battery proving too small later.
Home batteries come in different sizes to suit your energy consumption and needs. Below you can see which capacities are most common and which type of household or business they fit.
Small households
A 5 kWh battery is ideal for small households with low energy consumption. This size is often sufficient to cover basic needs during the night, such as lighting and some small appliances.
Suitable for: 1-2 person households or as emergency power supply.
Average household
A battery around 10 kWh is the ideal choice for an average family. This size provides enough storage to harness a large portion of self-generated solar energy and reduce grid power consumption.
Suitable for: Families of 3-4 people who want to be more self-sufficient.
Larger households or small businesses
A 15 kWh battery offers more energy independence and is suitable for households with higher consumption. You can be self-sufficient for longer periods, even during peak hours.
Suitable for: Large families (5+ people), homes with electric cars, or small businesses.
Commercial applications and large companies
These high-capacity batteries are designed for the largest energy users. They offer maximum flexibility, independence and are ideal for those who want to be completely disconnected from the grid.
Suitable for: Large companies or energy-neutral projects seeking maximum energy independence.
Unsure about which capacity best suits your home? Feel free to contact our team for personal advice.
A larger home battery offers several advantages, especially for households with high energy consumption or many solar panels. Here are some reasons to opt for a larger capacity:
While a large home battery offers many advantages, a smaller home battery may actually be more practical and economical in some situations:
Tip: lithium iron phosphate home batteries are light and compact, yet have a large storage capacity. This makes them suitable for both large and small applications.
The ideal capacity of your home battery depends on three factors: your power consumption, the capacity of your solar panels and your peak moments. Together, they determine how much energy you want to be able to store and use at times when the sun is not shining.
Your annual electricity consumption is the basis for the calculation. A small household consuming 3,000 kWh a year will need less storage than a large family using 7,000 kWh a year. The goal is to choose a battery large enough to absorb a significant portion of your daily consumption, but not so large that it rarely becomes fully full.
You can easily calculate your daily consumption by dividing the monthly consumption on your energy bill by the number of days. If you consume 300 kWh per month, that works out to an average of 10 kWh per day. With that information, you can estimate how much storage space you need to use the solar power from the day in the evening.
The capacity of your solar panels determines how much power you generate on sunny days and thus can store. This capacity is expressed in kilowatt peak (kWp). A 5 kWp installation can generate about 25 kWh of electricity on a summer day. You want to use this energy as much as possible instead of feeding it back to the grid.
The ratio of panel power to battery capacity is crucial here. Too little capacity means your power goes back into the grid, too much capacity means the battery often remains half full. The ideal balance is around 1 to 1.5 kWh battery capacity per kWp of solar panels. . So a 4 kWp installation works optimally with a battery of 4 to 6 kWh.
Besides your overall consumption, when you use electricity also plays an important role. Most households consume the most in the late afternoon and evening, when cooking, doing laundry and charging appliances. Those are your peak moments.
To calculate how big those peaks are, add up the power (in kW) of the appliances you use at the same time. For example: oven 2 kW + washing machine 1 kW + lighting 0.5 kW = 3.5 kW peak consumption. Your battery must be able to supply enough energy during those peaks. Therefore, it is wise to keep 10 to 20 per cent extra capacity as a buffer when calculating.
By combining your power consumption, the output of your solar panels and your peak demand, you can fairly accurately determine which battery capacity suits your situation. Here are three examples.
This household has six 400 Wp solar panels, accounting for 2.4 kWp of power, and an annual consumption of 2,800 kWh. That works out to 7.7 kWh per day. According to the rule of thumb, that yields a guideline of 2.9 kWh battery capacity (2.4 × 1.2). As peak consumption is low, a 3 kWh battery to largely self-supply daily usage.
This family has 10 solar panels of 400 Wp (4 kWp) and consumes 4,500 kWh annually, or 12 kWh per day. Using the formula 4 × 1.3, it comes to 5.2 kWh. As peak evening consumption rises to around 3.5 kW, a battery of 5 to 6 kWh ideal. This allows 70 to 80 per cent of solar power to be used directly in the home.
This family has 15 400 Wp solar panels, accounting for 6 kWp of power, and consumes 7,000 kWh annually, including car charging. That works out to 19 kWh per day. The formula 6 × 1.4 gives a guideline of 8.4 kWh. The high peak consumption of 7.2 kW (cooking, heat pump, car charging) adds 15 per cent margin. This brings the ideal battery to 9 to 10 kWh - large enough to power the house and partly the car.
Feel free to contact our team for personal advice. We will be happy to help you with all your questions on capacity, installation or savings.
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