Assessing your Solar Panel’s Efficiency

Solar panel efficiency is the measurement to evaluate the available electricity the solar panel can absorb from a ray of sunlight. To better understand this, I’ll first how solar panels work.

Inner Workings

The sun creates radiation that travels that we see as light. These waves travel in various wavelengths ranging in size. Solar panels absorb waves between 380 and 750 nanometres, in the spectrum of red to violet light. That totals to about 7% of all total light.

When the light hits your solar panels, the electric field scatters electrons from with the radiation. These electrons are trapped between the layers in the solar cell and pushed into the conductors that make electric current.

This process when there’s light on solar cells. Solar panels are rated with an efficiency rating between 11 and 21%. It calculates how much of the 7% of total light that the solar cell can convert into electricity.

For instance, a 21% efficiency solar panel gets almost twice the energy over its lifetime than an 11% efficiency panel. Most are rated by their maximum output. A high efficiency solar panel harvests more energy in a smaller or same-size package.

Reasons for Less Efficiency

Temperature: Panels lose efficiency at high temperatures because the heat affects the conductors and wiring. You can estimate the inside of your panels is twice the temperature of the air since the glass over the silicon works to increase the heat.

Most solar panels compensate for this, because they’ve usually been tested in conditions that don’t expose them to the maximum amount of sunlight. So, if it’s 30 degrees and very sunny, you could be harvesting more wattage than the maximum listed output.

Condition: Dirty, shaded, or broken solar panels are less efficient than clean ones. Even a thin layer of dust buildup can decrease the efficiency by preventing light from reaching the silicon. Regular cleaning is needed to maintain solar panels.

Construction: Many solar panel manufacturers note the efficiency rating of the cell. The entire panel might have a lower efficiency rating, due to the conductors and wiring. This doesn’t change how much energy your solar panels will create.

Direction: The direction of your solar panels will expose the solar panels to more or less light. Most solar installers will point your solar panels where they will be most efficient at noon, when you can collect the most power.

If you want to get an accurate account of what your panels are capable of, find the Performance Testing Conditions (PTC) or System Performance Testing Conditions (STPC). If you want to find out what solar panels are right for you, go to HahaSmart.com and try our price checker tool.

If you’d like more information, click here.

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