How much electricity can a solar panel generate?

How much electricity can a solar panel generate?

The solar panel rated power.

All solar panels are sold with determined so-called rated power and this is the maximum power a panel can reach under strict laboratory conditions.

There are a few test conditions but STC (Standard Test Conditions) are the most popular.

STC requires the following:

  • Solar irradiance 1000W/m2,
  • Cell Temperature 25°C,
  • Air Mass AM1.5

The solar panel rated power can vary based on technology and size from about 300W up to 600W. Unfortunately, modules are rarely reaching their rated power.


How much energy will a panel produce in one hour?

Energy generation varies on the weather and the time of day, but we can assume that when a panel is generating at 350W for one hour straight, it will produce 0.35 kWh of electricity. It can be simply calculated like so:

P x t = E


P – the power of solar panel [W]

t – time of generation at this power [h]

E – energy generated [kWh]

How much energy will a panel produce in one year?

Solar system energy generation is the highest in summer when there is a lot of sunlight and the smallest in winter months when the sun is low in the sky and for fewer hours than in the summer.

To estimate your system’s annual energy generation we can use the production ratio of kilowatt-hours to kilowatt-peaks (kWh/kWp). These can be easily found on

On the map below, you can see which areas of the US have a bigger potential for generating energy from solar panels.

Map source:

If we would place the same 350W panel in Phoenix and New York it would generate different amounts of energy.

In Phoenix, the production ratio is around 1900kWh/kWp while in NYC it would reach a value close to 1350kWh/kWp.

So in Phoenix, this panel would produce 665 kWh while in NYC it would produce only 472 kWh which is about 30% less.

To sum up!

Solar panels will produce different amounts of energy over the year in different locations in the US, but every location is good to invest in solar! The United States has good production potential in comparison to for example Europe where in different countries, the production ratio can vary from 800 to 1700 kWh/kWp while in the U.S.A those values vary from 1000 to 2000 kWh/kWp.