Solar sounds wonderfully simple: sunshine lands on the roof, and the refrigerator stays cold. But there are a few important pieces between those two events. This guide explains them without assuming you already speak fluent electrician.
1. Panels make electricity—just not the kind most appliances use
Solar photovoltaic panels produce direct current (DC) electricity when exposed to light. Household appliances generally use alternating current (AC). An inverter converts DC to usable AC. Actual production varies with sunlight, shade, temperature, orientation, and system losses.
Illustrative flow only: batteries may connect on the AC side or DC side depending on the system, and the utility grid is not necessarily downstream of the house.
2. Watts and watt-hours are different
Watts (W) measure power at a moment. Watt-hours (Wh) measure energy over time. A 100-watt device running for five hours consumes approximately 500 Wh (0.5 kWh). Real devices may vary in consumption.
3. What does a battery actually do?
A home battery stores energy for later use. Its usable capacity (kWh) helps determine runtime, while its power rating (kW) limits how much equipment it can run at once. A battery with plenty of stored energy can still be unable to start or support a large appliance.
4. What happens when the grid goes out?
Most ordinary grid-tied solar installations shut down during a utility outage for worker safety. A properly designed system with compatible battery storage, islanding controls, and transfer equipment can disconnect from the grid and power designated circuits. Solar panels alone do not guarantee backup power.
5. A real-world example
In the home behind our guides, the installed system includes ten nominal 400 W panels (10 × 400 W = 4,000 W, or 4 kW of panel nameplate capacity), a SolarEdge HD-Wave inverter, a Tesla Powerwall 2, and a Tesla Backup Gateway 2. Selected household circuits are backed up; the whole house is not. Panel rating is not a promise of continuous 4 kW output.
🔧 What we learned
The most useful first question isn't “How many panels can I fit?” It's “What do I want to keep running, and for how long?” Once you know that, the equipment specifications start making sense. Your refrigerator, unfortunately, does not care how impressive your solar panels look.