A solar panel can be overloaded when more current than it can supply is drawn from it. This is when the load on the solar panel far exceeds what it can produce.
Solar panels have been used to power large projects from skyscrapers to space stations. While they provide an unlimited source of energy, still only 3% of the world is powered by solar energy.
But just how much energy can solar provide and what happens if you overload a solar panel? Will that damage the solar panel or will it stop working? If you’re curious about what happens when you try to draw more energy than a solar panel can give you then this article is for you.
Here, we’ll look at the effects of overloading a solar panel and inverter. Also, is it possible to overcharge a solar panel?
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What Happens If You Overload A Solar Panel?
Overloading a solar panel by connecting a load much larger than it is capable of producing will not damage a solar panel. What is more likely to happen is the load or device connected will not function properly if at all.
Solar panels come in different sizes or capacities. The size here is the energy, measured in watts or amps. They can come in small ranges of between 5 to under 250-watt solar panels used to power small to medium size devices. Then there are the larger solar panels that range from 250 to 400 watts that are used to power homes. This is the power rating of a solar panel.
Devices also have a power rating. This is the amount of energy the devices use or need to run. Different devices draw different amounts of energy. Typically, the bigger the device, the more energy it uses.
|DEVICE||ENERGY CONSUMPTION IN WATTS (W)|
|Plasma screen TV||150-300|
The amount of power a solar panel produces and the amount of power the device it is connected to should be a match. This is where solar panel sizing is important.
Solar panel sizing
Solar panel sizing helps avoid a situation where the solar panel does not produce enough power to meet the demands of the load. To illustrate this, we will use the example of a solar battery.
A 100-amp hour battery stores about 1200 watts of energy. To find the right size panel, you must consider the output of the solar panel and how much sun it will receive. The more sunlight, and the higher the power rating of the solar panel, the quicker it will charge the battery.
|SOLAR PANEL OUTPUT (W)||CHARGE TIME (HOURS)|
If the solar panel does not produce enough power, the load will not work as it should. In the case of the example of a battery, it will take far too long to charge and might not even charge at all if the voltage in the solar panel is lower than the battery voltage. Source
Can Solar Panels Be Overcharged?
A solar panel cannot be overcharged. The earth receives up to 173,000 terawatts of energy from the sun. Solar panels absorb and convert a small fraction of that energy into electricity.
Solar panels work by first absorbing and then converting sunlight into energy. However, not all of the sunlight a solar panel is exposed to is absorbed and not all of the sunlight absorbed is converted to electricity. There are losses in the process.
A raw silicon solar cell absorbs almost 70% of light. Treating the cells with anti-reflective coating boosts the absorption to over 95%. Some of the light is reflected and this is one of the areas in which research is being made to improve the efficiency of a solar panel. Source
There is also the effect of heat. The temperature coefficient of a solar panel is a measure of the reduction in the efficiency of a solar panel as a result of a temperature rise. The average temperature coefficient of solar panels is between -0.2 to -0.5% per 1°C rise over 25°C. In effect, some of the energy absorbed in a solar panel is lost as heat.
Heat and reflectance are, however, not the main reasons why a solar panel cannot be overcharged. The main reason has to do with the limitations of a solar panel.
Do Solar Panels Have A Limit?
Solar panels are limited in how much energy they can convert to electricity. This is the efficiency of a solar panel. The maximum efficiency a solar panel can reach with the current technology is 33% for a single junction solar panel.
The technical term for this flaw in solar panel technology is the Shockley Queisser Efficiency Limit or SQ Limit. It is the primary reason why regardless of how much sunlight a solar panel absorbs it will only convert less than 35% into electricity.
This happens because of recombination. Recombination is a reversal of the process that leads to an electric current being created in a solar cell.
How Much Can You Overload A Solar Inverter?
Overloading an inverter is when a solar array is sized to produce more electricity than the inverter’s maximum output capacity. The recommended overload is between 10 to 20%.
Why would there be a need to overload an inverter by oversizing a solar array? Would that not damage the inverter?
Oversizing a solar array is a best practice for solar system design. The reason for oversizing an array is to compensate for losses in solar energy production. Under standard test conditions in a laboratory, a solar panel produces close to its power rating. In real-world conditions, a solar panel will produce less due to factors including:
- Positioning of the solar panels. This relates to the site, orientation, and tilt of the array.
- Heat-induced losses.
- The sun’s position in the sky throughout the day.
- Dirt and cloud cover.
Because of these potential losses, oversizing an array compared to the inverter capacity allows for the balancing of the system to improve its efficiency.