How Many Solar Panels Do You Actually Need?

A lot of people ask us this question. The honest answer is: it depends on what you want to power. But we can give you a framework to figure it out yourself in about 10 minutes.

Step 1: Know your daily power use

Start with the appliances you want to run. Write down each one and how many hours per day you use it. Multiply wattage x hours = watt-hours per day.

Common examples:

• LED lights (10 bulbs): 60W x 5 hours = 300Wh
• Refrigerator: 150W x 8 hours = 1,200Wh
• Phone/laptop charging: 50W x 2 hours = 100Wh
• Well pump (1/2 HP): 370W x 1 hour = 370Wh

Add them up. That is your daily load. Want a fuller breakdown of what common appliances actually draw? See our guide on how much power your appliances use. The U.S. Department of Energy also publishes a helpful appliance energy-use guide and online calculator if you want to nail down a specific model.

Step 2: Account for eastern Washington sun hours

Oroville and the Okanogan Valley average about 5-6 peak sun hours per day in summer, dropping to 3-4 in winter. For a year-round system, plan around 4 peak sun hours. Eastern Washington gets far more usable sun than its reputation suggests — here's the data.

To pull accurate sun-hour and production numbers for your exact address, NREL's free PVWatts Calculator is the industry standard.

Step 3: Do the math

Daily load / peak sun hours = panel wattage needed

Example: 2,000Wh / 4 hours = 500W of panels

At 300W per panel, that is 2 panels for a basic off-grid setup — more if you want battery storage buffer. For the full step-by-step, including battery and inverter sizing, read how to size an off-grid system.

Our recommendation

For most eastern WA homesteads and cabins, a 4-6 panel setup with battery storage covers the basics comfortably. Our used 300W panels at $90 each make this affordable — a 6-panel starter array runs about $540.

Come out to the depot in Oroville and we will walk through your setup with you, or browse our current panel stock to get started.