Quick Answer
To determine how much solar power you need for battery charging, calculate your daily energy requirements and select a solar panel system that provides 20-30% more power to account for efficiency losses. Consider factors like battery capacity, charge controller efficiency, and system voltage. A general rule of thumb is to start with a minimum of 200 watts of solar power for small battery banks.
Choosing the Right Battery Bank
When selecting a battery bank for your off-grid system, consider your energy needs and the number of days you want your batteries to last. A general rule of thumb is to calculate your daily energy requirements in watt-hours (Wh). For example, if you want to charge a 12V, 100Ah battery, your energy requirement would be 100Ah x 12V = 1200Wh (or 1.2kWh) per day. If you want your batteries to last 3 days, you would need a minimum of 3.6kWh per day.
Calculating Solar Panel Requirements
To calculate the solar panel requirements, you need to consider the total daily energy requirement, battery capacity, charge controller efficiency, and system voltage. Assuming a 20% efficiency loss due to charge controller and wiring losses, you would need to increase the total daily energy requirement by 20%. For example, if your daily energy requirement is 3.6kWh, you would need 4.32kWh (3.6kWh x 1.2) of solar power per day. To determine the required solar panel size, divide the total daily energy requirement by the number of peak sun hours (PSH) your location receives per day. For example, if your location receives 5 PSH per day, you would need at least 4.32kWh / 5 PSH = 864W of solar power per day.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.