How much solar do I need?

Start from your real daily energy use in kilowatt-hours, divide by your area’s peak sun hours, then add 25 to 30 percent for losses. That gives the panel size. The battery is sized separately, from how much of that energy you need after dark.

What are peak sun hours?

The number of hours per day your panels effectively make full rated power. It is not daylight hours. A sunny location averages around 5, less in winter or under cloud. It is the single biggest variable in solar sizing.

Why start with my electricity bill?

Your bill shows your real consumption in units (kWh) and reveals which appliances dominate it. Sizing solar or backup from guesses wastes money. Sizing it from your actual usage is the difference between a system that fits and one that does not.

Solar & Energy: Sizing Panels From Real Use

Almost every oversized, overpriced solar quote comes from skipping the first step: knowing your own consumption. Once you have that in kilowatt-hours per day, the rest, panel size, battery size, even whether solar makes sense at all, follows from simple math and your local sun.

Start from energy, not panels

Your electricity bill is the honest starting point. It reports your usage in units (each unit is one kilowatt-hour) and, once you read it properly, shows which appliances drive the total. Add up the daily kWh you want to cover, and you have the demand the system must meet. Not sure of an appliance’s share? The appliance wattage calculator turns watts and hours into daily and monthly kWh.

Peak sun hours change everything

Panels only make full power for part of the day. Peak sun hours, the effective hours of full output your location gets, is the number that separates a system that works in a sunny country from one that stalls in winter. A sunny area averages around five; use a lower figure for the worst months so you are not caught short.

From demand to panel and battery size

Divide your daily energy by your peak sun hours to get the rough panel size in kilowatts, then add 25 to 30 percent for real-world losses in panels, wiring, and the inverter. The battery is sized separately, from how much of that daily energy you need to carry through the dark hours, and from the usable depth of your chosen chemistry.

Work it from your own numbers Use the appliance wattage calculator to turn your load into daily kWh, then read the guides below to size panels and a battery around it.