Do solar panels work in cloudy, overcast or rainy days?

Yes, solar panels produce electricity even on cloudy and overcast days but expect it to be less than when the sky is clear. A solar  panel generates its maximum rated power (watts) when exposed to a light intensity of 1,000 w/sqm (92.93w/sqft) at a temperature of 25°C (77°F).

The clouds or rain diffuse the sunlight reaching the panel and lower its intensity which explains why the panel produces less electricity under cloudy or rainy skies.

So, solar panels can work without direct light but will produce less electricity. Because of this, your batteries will take longer to charge when the solar panels are not exposed to direct light!

Perhaps you are worried about the security of your solar panel or simply don’t want to mount them on your car and boat roof.

Take note, solar panels placed behind a glass, acrylic, tinted windows still produce electricity but not as much as when they are exposed to sunlight directly.

This is because the glass material absorbs and reduces the intensity of the sunlight reaching the solar panels depending on the actual materials used in the glass, and how clear and clean it is.

In fact, you should place solar panels behind glass only when you need to keep your batteries topped up and not to charge them fully.

How temperature changes solar panel power production

Surprisingly, the solar panel power output is affected by how hot the solar panel is. During hot weather, the power output of your solar panels is lower compared to during cooler weather.

Don’t be shocked then when you see dips in the energy produced by your solar system on extremely hot days!

To counter this, here are a couple of tips that can help minimize the power dips:

  • If you live in an extremely hot weather area, oversize your solar panels to compensate for the lower power output.
  • If you are installing your panels on a house or motor home, provide for airflow below the panels and the roof surface to keep the panel temperatures low.

Do solar panels work in a shade?

Shade is bad for your solar panel’s electricity production. In order to harvest as much electricity during the day -locate your panels where there is no shade.

If you plan to mount your panels on the roof, make sure that the planned installation location for your panels is exposed to as little shade as possible throughout the year.

Shade falling on a solar panel has the potential negative effect of reducing its electricity production by as much as 1/3 to zero depending on the amount of shade cover and the solar panel’s diode bypass configuration.

Do solar panels work in artificial light?

Yes, the can work under certain types of artificial light but expect their power output to be much lower than when exposed to natural light.

Do solar panels work in winter?

Yes, provided they are exposed to sunlight, your solar panels will produce electricity during winter.

Overall, expect your solar panel power output to go down considerably because of lower direct sunlight and quite likely snow covering your solar panels for several days.

Are your solar panels angled to help the snow slide off on its own? Can you rake it off the roof safely? Doing this helps minimize the low power production caused by snow covering your solar panels.

When you look at the different environments that solar panels are exposed to, it is clear that monitoring solar panels performance is important.

Perhaps you have a basic solar system with a simple MPPT or PWM charge controller and you want to tell how well your solar panels are working.

Simple checks: How well your solar panels are working

Your charge controller status shows how well your solar panels are working. Some controllers use blinking LEDs to show that the solar panels are charging

Modern controllers have in built voltmeter and ammeter that show:

  • solar panel voltage
  • solar panel charging current

Does your charge controller log how your daily energy production? I find it is easiest to compare your daily energy production (Wh) against your design or expected energy production.

For example, a 100W, 12V panel in a 4 hour location, should give you about 400Wh. How much energy was your system generating at commissioning and how much are you getting now?

Take note of charging current compared to expected current. This can help you troubleshoot a solar system that is not performing well.

All in all, expect solar panels to produce maximum power when exposed to direct sunlight in cool temperatures.
Winter, placing them behind glass, rain reduce how much electricity they produce.

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