Quick Answer
An off-grid solar system consists of a photovoltaic (PV) array, a charge controller, a battery bank, an inverter/charger, and an AC distribution panel.
Off-Grid Solar System Design Fundamentals
When designing an off-grid solar system, the first step is to calculate the total load in watt-hours (Wh) per day. This requires identifying all appliances and their respective power consumption in watts (W). For example, a refrigerator might use 200W, a laptop 50W, and a LED TV 120W. The total load is then calculated by adding these values and multiplying by the number of hours the appliances are used per day.
Load Calculation and System Sizing
A general rule of thumb is to size the solar array to provide at least 30% of the daily load in excess of the average daily load. This excess energy is used to recharge the battery bank during the day, which in turn powers the load during the night. For example, if the total load is 2 kWh (2000 Wh) per day, the solar array should be sized to provide at least 600 Wh (30% of 2000 Wh) in excess of the load.
Panel, Battery, and Inverter Sizing Worksheet
To ensure accurate system sizing, a worksheet can be used to determine the required panel, battery, and inverter/charger sizes. The worksheet should include columns for the following:
- Load (Wh/day)
- Excess energy (Wh/day)
- System voltage (V)
- Array size (W)
- Battery bank capacity (Ah)
- Inverter/charger size (VA)
By using the worksheet and following the guidelines outlined above, a well-designed off-grid solar system can be created to meet the needs of a specific load and environment.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.