The number of solar panels needed to fully charge a home battery depends on various factors such as the battery's capacity, the efficiency of the solar panels, and the amount of sunlight in your region. Below, we explain step-by-step how you can calculate this:

Home Battery Capacity

The capacity of a home battery is expressed in kilowatt-hours (kWh). This indicates how much energy the battery can store.

• Example: If you have a home battery with a capacity of 10 kWh, you need to generate at least 10 kWh of solar energy to fully charge the battery.

Daily Yield of Solar Panels

Solar panels produce electricity depending on their power (expressed in watt-peak, Wp) and the available sun hours.

• Average production: In the Netherlands, 1 Wp annually yields approximately 0.85 kWh. This means that a solar panel of 400 Wp yields about 340 kWh annually.

• Daily production: Divide the annual yield by 365 days. A panel of 400 Wp yields an average of 0.93 kWh daily.

Calculation of the Number of Required Panels

To determine how many solar panels you need, divide the battery capacity by the daily production per panel.

• Calculation example:

  • Battery capacity: 10 kWh.

  • Daily production per panel: 0.93 kWh.

  • Number of panels: 10 kWh/0.93 kWh/panel≈11

So you need approximately 11 solar panels of 400 Wp to fully charge a 10 kWh home battery in a day.

Other Important Factors

• Seasonal variations: In winter, solar energy production is significantly lower than in summer. Your system needs to be adjusted accordingly.

• Energy consumption: If you use a lot of energy directly during the day, less will be left for charging the battery.

• Loss during storage and conversion: About 10% of the energy can be lost during the charging and discharging of the battery. Consider this when calculating the number of panels.

Advice from a Professional

For an accurate calculation and optimal system design, it is advisable to consult a professional installer. They consider the orientation of your roof, potential shading, and your energy consumption pattern.

Frequently Asked Questions

1. How many solar panels are needed to fully charge a home battery?
   The number depends on the capacity of your home battery and the power of the solar panels. For a battery of 10 kWh, for instance, you need approximately 11 solar panels of 400 Wp under average conditions.

2. Does seasonal sunlight affect the charging of a home battery?
   Yes, in winter solar panels produce less energy due to shorter days and less intense sunlight. This may mean you need more panels to generate enough energy during this period.

3. Should I consider energy loss when charging the home battery?
   Absolutely. About 10% of energy can be lost during the charging and discharging of the battery. When calculating the number of solar panels, it's wise to account for this.

For a home battery of 10 kWh, you need about 11 solar panels.