Talk to anyone who lives on off-grid solar and we’ll tell you, “rain should only ever come at night.”
We like rain, to be certain. Rain helps the garden grow, washes away the little piles of poo made by our flock of chickens, and generally makes everything feel fresh and green. But, if I could make one small request, please, oh PLEASE, only rain at night.
This is because solar panels generally do not work well during the rain.
Solar cells require direct sunlight in order to perform and with rain comes clouds. And it is these clouds that will inevitably hinder the amount of sunlight that is able to strike your panels, thusly limiting their ability to generate power.
Table of Contents
Water On Solar Panels
It’s worth noting that it is not the rain water itself that is most problematic to power production, but rather the clouds associated with precipitation.
There have been rare occasions at our house where a lone rain cloud comes in directly overhead, but still manages to leave a clear line-of-sight between the sun and our solar array.
In this situation, the power output diminishes only slightly, as sunlight is still being defused by the rain droplets but is not completely blocked as it would in the case of a rain cloud.
An easy way to see how this works is by hosing down your solar panels with a garden hose.
The water will slow sunlight as it attempts to strike your panels. But with the water being clear and in relatively short supply, the light will still reach the solar cells. However, if you were to simulate cloud cover by throwing a blanket over your panels, you could expect to see a dramatic drop in power production.
Benefits Of Rain On Solar Panels
Now that we’ve established that rain is primarily a negative when it comes to solar panels working efficiently, it should be noted that rain can provide a small positive service as well.
As mentioned above, solar cells require direct sunlight in order to operate at their maximum potential. And while clouds are very adept at blocking the sun, they are not the only thing that can.
Blemishes such as dust and smoke residue can also prohibit your panels from direct sunlight.
For example, where we live in ‘Rural-ville’, farmland is everywhere. Consequently, every spring when the fields get plowed and every fall when crops get harvested, we have an excess of dust in the air. And we know this because we see it on our house windows (effectively driving a certain someone bonkers after they ‘just washed them!’)
In our case, this only happens twice a year and, to date, we have not felt compelled to wash the solar panels as rain seems to do this well enough for us.
However, if we were to live close to a dirt road, this might be different as dust would be kicked up more frequently by regular driving. In this situation, we might have to rinse panels a few times a summer.
Another more serious blemish would be the smoke produced by burning.
Things like bonfires, burning leaves or even old coal powered power plants, can produce a very heavy residue that will leave your panels covered in a sun inhibiting film. If left unchecked, this would clearly reduce power output from your solar array.
Most people live their entire lives without giving any significant thought to how much power they actually use. For those of living in the industrial world, power generally seems to be unlimited.
But I can tell you, that all changes when you ‘unplug’ from the power grid.
I never realized just how fickle regular sunshine could be until I went off-grid solar. Everything from a heavy fog to a light snow can ruin your window of ‘power production’.
And while it might seem like the odds are stacked against you, take a moment to understand that solar and battery technologies are not standing still. Point of fact, they are improving at a phenomenal pace.
So don’t let a little rain discourage you.
With what is available right now, if you’ve done your homework right, you can feel confident enough to sit back and say, “let it rain!”