How Does Shade Affect Solar Panels?

Solar panels work by converting photons (or, light particles) into electricity we can use. When something blocks light from reaching solar panels, they can’t produce energy. Solar panels sitting in complete shade simply won’t work. But how much shade is too much shade for a solar panel and how can you minimize efficiency loss when the sun is weak? Today, we find out.

Can Solar Panels Work in the Shade?

The answer to this question is no, not really. Shade has a much greater impact on solar panel efficiency than people think. A standard solar photovoltaic (PV) system serving a small business or medium-sized home has a capacity of 3 or 5kW per hour. This translates to anywhere between 15 and 30 solar panels, depending on the size and shape of your roof and the system you choose.

Grass with solar panels on them

Solar panels alone cannot generate electricity that is instantly safe to use. All solar panel systems feature an inverter that converts solar electricity into AC (alternating current) electricity. AC can be used to power home appliances and can be channeled successfully back into the grid.

Shade is a big issue because of the way solar panels are connected. Rather than stand-alone panels that can work efficiently even if other panels in the system don’t, solar panels are arranged into strings. Strings consist of a number of panels working together and if one panel drops out, the electricity generated by the previous panels cannot reach the inverter.

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A bit like an old-fashioned string of Christmas lights where each bulb connected with the next on one electrical wire. For as long as one of the panels sits in shade, the entire system fails. With some older systems, even a few shaded cells can cause a power outage.

How Can You Reduce the Effect of Shade on Your Solar Panels?

Consider the effect of shade on your solar panels before installation. Shade is usually caused by trees on or near your property, or the shape of your roof. Consider these factors before the solar panels are fitted, noting how much of your roof is in shade at different times of the day.

2 men with white hard hats surrounded by solar panels.

It may be possible to simply trim foliage and plan the layout of your solar panels to avoid shade completely. If shade is unavoidable, you may need to buy a solar power system with a special type of inverter that minimizes power loss.

There are three types of inverter:

String Inverters

This inverter is part of the system described above. The most basic but also the most common type of inverter out there, a string inverter system will fail even if only one panel is in shade.

Microinverters

Microinverters are small inverters that are installed on each individual solar panel. This means each panel can work on an individual basis and maintain peak efficiency even if a neighboring panel is in shade.

Power optimizers


Power optimizers operate somewhere in between string inverters and microinverters. Power optimizers are installed at each solar panel, like microinverters, but they send the electricity generated to a single string inverter. Again, a single shaded panel cannot affect the system as a whole.

Both microinverters and power optimizers will increase the cost of your solar power system. However, if you know your roof is partially or completely in shade for part of the day, it’s can be well worth the investment. The more electricity your solar panel power system creates, the more money you save.

A Note About Clouds

“Wear sunscreen even when it’s sunny” is sound advice. UV light, known to be a leading cause of skin cancer, can harm our skin, even on a cloudy day. That’s because clouds may minimize the amount of light that reaches us but clouds have no impact on the sun’s radiation. Solar panels can still generate electricity on cloudy, overcast days!

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