How Many Solar Panels to Run a Washing Machine? (Calculator + Examples)
A typical washing machine uses about 0.5 kWh per load on cold water settings -- drawing 400-500W over a roughly 1-hour cycle. You need just 1 standard 400W solar panel at 5 peak sun hours to cover one load per day, with plenty of energy left over for other small loads.
Quick answer
A 400W solar panel produces about 1.66 kWh per day at 5 peak sun hours (400W x 5h x 0.83 derate). A washing machine uses only 0.5 kWh per load, so one panel covers it more than three times over.
| Peak Sun Hours | 200W Panels | 300W Panels | 400W Panels |
|---|---|---|---|
| 3 PSH (very cloudy) | 1 | 1 | 1 |
| 4 PSH (cloudy) | 1 | 1 | 1 |
| 5 PSH (US average) | 1 | 1 | 1 |
| 6 PSH (sunny) | 1 | 1 | 1 |
| 7 PSH (desert SW) | 1 | 1 | 1 |
Formula: panels = daily kWh / (panel watts x PSH x 0.83 derate), rounded up. Even with a single 200W panel at just 3 PSH, you produce 0.50 kWh -- right at the threshold.
Washing machine energy breakdown
Washing machines are surprisingly efficient on the electrical side. The real energy cost comes from heating water -- which is why cold water washes are so important for solar sizing.
| Specification | Value |
|---|---|
| Wattage range | 400W - 500W (motor only) |
| Average wattage | 450W |
| Run time per load | ~1 hour |
| Loads per day | 1 (average household) |
| Duty cycle | ~75% during cycle |
| Daily energy use (cold wash) | 0.5 kWh |
| Monthly energy use | 15 kWh |
| Yearly energy use | 183 kWh |
Important note on hot water: If you use hot water settings, the washer's internal heater or your water heater adds significant energy. A hot wash can bring total energy per load up to 2.0-2.5 kWh. The numbers above assume cold water washing, which ENERGY STAR recommends for both energy savings and fabric care.
Try the calculator
Adjust the panel wattage and your location's peak sun hours to see exact production numbers for your setup.
Benchmarks: U.S. avg 4.98 · Phoenix 6.54 (highest) · Seattle 3.95 · Anchorage 3.17 (lowest). Above ~5.5 = sunny · 4.5–5.5 = average · below 4.5 = cloudy.
Tap to see sensitivity analysisSensitivity analysis
| Scenario | Value |
|---|---|
| Low (-20%) | 1.3 kWh |
| Expected | 1.6 kWh |
| High (+20%) | 1.9 kWh |
Your daily production scales linearly with both panel wattage and peak sun hours. A 10% change in either input changes your result by 10%.
Running it off-grid
A washing machine is one of the easiest appliances to run off-grid because of its low total energy consumption and intermittent use pattern.
Battery bank sizing:
- Daily consumption: 0.5 kWh
- Autonomy target: 2 days
- Total energy needed: 0.5 x 2 = 1.0 kWh
- At 12V with lithium (LiFePO4) batteries at 80% depth of discharge: 1.0 kWh / 12V / 0.80 = 104 Ah
- At 48V: 26 Ah
Charge controller: A single 400W panel needs only a 10-15A MPPT charge controller. Even a basic 20A controller is more than enough and leaves room for additional panels.
Inverter: Washing machine motors draw 400-500W during agitation but can spike to 800-1,000W during the high-speed spin cycle. A pure sine wave inverter rated at 1,500W handles this comfortably. Pure sine wave is recommended because modified sine wave inverters can cause motor buzz and reduced efficiency.
Practical tip: Run the washer during direct sunlight hours. A single 400W panel can power the washer in real time during a sunny afternoon, meaning you do not even need to draw from batteries.
See our battery charging calculator for exact sizing.
Running it grid-tied
Grid-tied is the easiest setup for a washing machine. Your single 400W panel produces 1.66 kWh per day, while the washer uses only 0.5 kWh per load. The surplus 1.16 kWh goes to the grid via net metering and can offset other appliances -- including the dryer.
Since the washer uses so little energy relative to one panel's output, this is an excellent candidate to pair with other loads. One panel can realistically cover a washing machine plus a microwave or a few hours of TV.
Energy-saving tips for washing machines
These tips can cut your washer's energy use by 50% or more:
- Wash in cold water. This is the single biggest change you can make. Cold water cycles use 0.3-0.5 kWh compared to 2.0-2.5 kWh for hot. Modern detergents are formulated for cold water and clean just as effectively.
- Run full loads. A half load uses nearly the same energy as a full one. Wait until you have a full load, or use the load-size selector if your machine has one.
- Use high-speed spin. Faster spin extracts more water, which means less time in the dryer. This is especially valuable if you are also powering a dryer with solar panels.
- Choose a front-loader. Front-loading washers use 25% less energy and 45% less water than traditional top-loaders. They also have faster spin speeds.
- Skip the extra rinse cycle. Unless someone in your household has sensitive skin, the standard rinse is sufficient. An extra rinse adds 0.1-0.2 kWh.
- Clean the lint filter and inlet screens. Clogged filters reduce water flow and can extend cycle times.