Solar panels for a washing machine: how many do you need?

Many people think the washer is a power monster. Truth: in cold water it draws only 100-250 Wh per cycle. The monster shows up when you heat water — then it climbs to 1.5-2.5 kWh per load. Here's how to size your system without overbuying panels.

What your washer actually uses

• Cold eco cycle (86 °F): 0.4-0.6 kWh per load
• Warm cycle (104 °F): 0.8-1.2 kWh per load
• Hot cycle (140 °F): 1.3-1.8 kWh per load
• Sanitize cycle (194 °F): 1.8-2.5 kWh per load

How many panels you need

If you do 4 cold-water loads a week (1 kWh × 4 = 4 kWh/week ≈ 0.57 kWh/day) in a 4.5 PSH location: 570 ÷ 4.5 × 1.3 = 165 W. One 200 W panel covers it. If you run hot loads daily, bump to 2 × 410 W panels.

The trick: wash during sun hours

Set the washer to start between 11:00 and 14:00. In that window panels produce so much that the whole cycle runs straight from solar, never touching the battery. That's called direct self-consumption and it's the most efficient use of solar.

Inverter sizing

Motor inrush plus water heating element can hit 2,500-3,000 W. You need a pure-sine-wave inverter of at least 3,000 W with 6,000 W surge. Cold-only? A 1,500 W inverter is plenty.

If you also run a solar fridge and microwave, check aggregated sizing in how many panels for a house.