How much electricity does a solar panel produce?

The amount of electricity a solar panel produces depends on three important factors: the size of the panel, the efficiency of the solar cells inside, and the amount of sunlight the panel gets.

We’ll break down what you can expect from a typical solar panel, and how that power output compares to the power you need for the gadgets and appliances you use inside your home.
Why does solar panel size matter?
The more solar cells working in tandem, the more power they’ll create. That’s why the size of the panel matters if you’re trying to calculate how much electricity a panel makes.
Solar panels have been about this size for decades, but modern panels make more electricity than in the past. That’s because panel manufacturers have found ways to improve cell efficiency over time.
How much electricity does a solar panel produce?
by Ben Zientara
A picture of some solar panels on a roof producing solar energy
The amount of electricity a solar panel produces depends on three important factors: the size of the panel, the efficiency of the solar cells inside, and the amount of sunlight the panel gets.
We’ll break down what you can expect from a typical solar panel, and how that power output compares to the power you need for the gadgets and appliances you use inside your home.
How big are solar panels?
When we say “solar panel,” what we’re talking about is a typical silicon photovoltaic panel for residential use. These days, most solar panels are about 5 and a half feet tall and a little more than 3 feet wide:
If you look closely at the solar panel in the image above, you’ll notice 60 little squares. These squares are actually individual solar “cells,” which are linked together by wires. The cells are where electricity is made, and the wires carry the electricity to a junction box where the panel is hooked into a larger array.
Why does solar panel size matter?
The more solar cells working in tandem, the more power they’ll create. That’s why the size of the panel matters if you’re trying to calculate how much electricity a panel makes.
Solar panels have been about this size for decades, but modern panels make more electricity than in the past. That’s because panel manufacturers have found ways to improve cell efficiency over time.
Comparing solar panel efficiency from 1954 to 2018
How efficient are solar panels?
Solar efficiency relates to the amount of available energy from the sun that gets converted into electricity.
Back in the 1950s, the first solar cells were capable of taking 6% of the energy from the sun and converting it into electricity.
If they were configured to be the same array of 60 cells you see in the image above, that would have created a current of about 20 watts electricity, about a third of what would be needed to light up a 60 watt incandescent bulb.
When we originally wrote this page in 2012, solar cells could convert 15% of the energy hitting them from the sun into power. As of 2018, the efficiency of the most advanced solar cells is closer to 23%, while average solar cells for residential use are around 18.7% efficient.
If you combine the efficiency of the cells with the size of the panel, you get a number called the “power rating.” In the solar industry, we say “that panel is rated to produce X watts.”