Is it advisable to oversize your solar array for winter production?

Calculating Winter Production Requirements

When determining the required increase in solar array size for winter production, consider the decrease in solar irradiance during the winter months. In the Northern Hemisphere, solar irradiance can be as low as 200-300 Wh/m²/day during the winter solstice. For example, if your typical summer production is 10 kW, you may need to add 2-3 kW to your array size to account for the reduced solar irradiance during winter. However, this increase will depend on your location’s specific climate and solar irradiance patterns.

Solar Kilowatt-Hour Math

When calculating the required increase in solar array size, use the following formula: (Winter production / Summer production) x 100. For instance, if your winter production is 70% of your summer production, you would need to increase your array size by 30%. This can be achieved by adding more panels or increasing the efficiency of the existing panels. Keep in mind that increasing the panel efficiency can be more cost-effective than adding new panels.

Practical Considerations

When oversizing your solar array for winter production, consider the following practical considerations: battery bank size, charge controller capacity, and inverter size. You may need to upgrade your battery bank to store excess energy generated during the summer months and discharge it during the winter. Additionally, consider the impact of oversizing on your system’s overall efficiency and potential losses due to increased panel mismatch and shading.