The number of solar panels needed to fully charge a home battery depends on various factors such as the capacity of the battery, 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:

Capacity of the Home Battery

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 Output 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 generates approximately 0.85 kWh annually. This means that a solar panel of 400 Wp generates about 340 kWh annually.

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

Calculation of the Number of Required Panels

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

• Calculation example:

  • Capacity of battery: 10 kWh.

  • Daily production per panel: 0.93 kWh.

  • Number of panels: 10 kWh0.93 kWh/panel≈11\frac{10 \, \text{kWh}}{0.93 \, \text{kWh/panel}} \approx 110.93kWh/panel10kWh​≈11.

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

Other Important Factors

• Seasonal variations: In winter, solar energy production is significantly lower than in summer. Your system should be adjusted for this.

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

• Loss during storage and conversion: Approximately 10% of the energy can be lost during 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 wise to consult a professional installer. They take into account the orientation of your roof, any 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 10 kWh battery, you will need about 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 can mean that you need more solar panels to generate sufficient energy during this period.

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

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