As a family who has lived with off-grid power since December 2015, we get asked a LOT of questions regarding solar panels. One of the more common questions is, ‘do solar panels work at night?’
The answer to that is, ‘No, solar panels absolutely do NOT work at night.’
Point of fact, our solar panels have proven to shut off a good 45 minutes before actual sunset. For a look into this, check out, ‘How Many Hours A Day Do Solar Panels Work?’.
To understand why solar panels do not produce electricity at night, it pays to understand photovoltaics, or more directly, the photovoltaic effect.
Solar Panels And Photovoltaics
Greatly simplified, photovoltaics is the process where light (electromagnetic radiation) comes in contact with a semiconductor material, and as a result, electrons are excited. It is this ‘excitation’ – or movement of electrons – that is the basis of the DC (direct current) power produced by solar panels.
Knowing this, we can easily deduce that in the absence of light, there would be no power production.
In other words, solar panels do not work at night as there is insufficient electromagnetic radiation (sunlight) coming in contact with the semiconductor materials that make up your solar cells. And without sufficient input levels, electron movement will not reach the point to where notable DC power is produced.
Do Solar Panels Work With Artificial Light?
Believe it or not, I have had quite a number of people ask if my solar panels would work if I shone my vehicles headlights on them.
The practical answer to that is no. But there are caveats to this.
In theory, electrons never stop moving. So there would definitely be some sort of response in the semiconductor material of the solar cells from having the high-beams of my vehicle shining on them. But there are two points that must be understood.
- First, the emitted radiation (light) from your headlights is going to be of a different makeup than that of natural sunlight (think house light vs grow light). And with solar cells being engineered for natural sunlight, it only makes sense that the level of electron excitement would be significantly less when the wrong recipe of light is present.
- Second, there is more to producing power than just solar panels. The panels for our array are connected to controllers. And I can tell you, these controllers will not engage until specific criteria are met.
To give you an example, our solar panels do not immediately begin producing power at sunrise. You will hear the controllers audibly start to click on and off first thing in the morning, but it is not until the outdoor light level has risen some, before the controllers have enough sunlight to stay engaged.
Keep this in mind when considering your vehicles headlights.
Unless your headlights are able to duplicate the level of intensity of the morning sun, then your controllers are not likely to stay committed and therefore your panels will be essentially shut off.
Solar Panels After Dark
So now that we know that solar panels do not work at night, how are we to power our homes when the sun goes down?
There are two common choices for this situation.
- Power from the electric company – For those who are grid-tied (meaning have a physical connection to the electric utility), the most common solution to the absence of power producing sunlight is to simply pull power from the grid.
In other words, when the sun is shining, your panels can give you power. But when it is not, the electric company steps in and provides you what you need to keep your home working.
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The overwhelming number of panel owners use this type of situation; due largely to its convenience and low installation costs.
- On-site storage – For any off-grid solar powered home (meaning you have no connection to the electric utility) on-site storage is an absolute must. Whole house batteries are employed to store enough energy for those times where the sun does not cooperate.
An excellent example of this is the Tesla Powerwall.
Although mostly utilized by grid-tied solar users, the Powerwall allows homeowners to store energy during the day so that they don’t have to buy electricity from the power company for overnight use.
This storage device can also cover for short blackouts when the power grid is down.