Understanding Your DIY Solar Output Posted on 27 Feb 07:00

The concept of DIY solar output can be confusing for many customers who are curious about renewable energy systems.

understanding solar output

Energy production from a rooftop panel array usually doesn’t match the published, rated capacity of the photovoltaic modules. In other words, an 8 kW system doesn’t actually create 8 kW of solar electricity on a daily basis.

But why not?

The answer is surprisingly simple, and it doesn’t indicate a problem with your DIY rooftop photovoltaic system.

DIY Solar Panel Ratings Aren’t Based on Real-Life Conditions

Before going to market, photovoltaic panels are put through tests to evaluate their performance. These tests are completed under standard test conditions (STC), at 77 degrees Fahrenheit under 1,000 watts per square meter of solar light.

Photovoltaic panel power ratings are based on the results of the STC testing, not the conditions they will operate under on your rooftop.

In the real world, temperatures don’t hold steady at 77 degrees day in and day out. The sun isn’t always at the same place in the sky either, producing a consistent amount of light. Consequently, a difference in solar output isn’t surprising.

Realistic Expectations for DIY Solar Output

Other factors — known as derate factors — will also affect the energy output of your DIY solar system. Photovoltaic modules and inverters are highly efficient, but some energy is naturally lost when converting from DC to AC power. Wiring, connections and environmental issues like shading and soiling also decrease the system’s net power production.

Although you can take steps to reduce some derate factors, many are unavoidable. In fact, even professionally installed photovoltaic arrays experience similar system losses.

So what level of production can you realistically expect from your DIY rooftop system?

On average, homeowners net about 83 percent of the total rated capacity of their photovoltaic panels. Taking our example above, for an 8 kW system, this equates to roughly 6.6 kW of solar electricity.

Sizing Your Array for Sufficient Solar Output

Fortunately, you don’t have to do any math to design an effective rooftop photovoltaic system for your home. Nor do you have to research or calculate the sunlight and temperature conditions in your area.

The Solar GOODs DIY solar calculator does the job for you, taking all of this important information into consideration in sizing an efficient photovoltaic array. Type in your address and answer a few simple questions, and the calculator automatically determines how many photovoltaic panels you will need.

Powering your home with photovoltaic electricity is easy with Solar GOODs, your DIY superstore for energy independence. Visit us online today to learn more about DIY solar output and to get started on designing your rooftop system.