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Science tells us that energy cannot be destroyed, only transformed. So what will happen if you do not connect any load to solar panels? Where will the energy go and more important, is it safe to just leave your solar panels like that?
A solar panel will still generate a high voltage, but it will be conducted through the cells. The cells in the solar panel will get hotter as the voltage increases, but the cell surface is large enough to handle the heat. The solar net meter will not run until a load is plugged into the system.
What Happens to the Solar Panels
Solar panels are made of photovoltaic cells. When the sun strikes the cells, a process transforms solar energy into electrical power, or direct current (DC).
Another way to visualize the process is like this. When sunlight strikes a solar cell, an electron gets released. The electron flows down the cables and turns on a TV, microwave or whatever you loaded onto the system.
If there is no wiring for the electron to go through, it will just remain there. There is voltage in the panels but current requires cables to flow and deliver power to electronics, appliances, motors etc.
DC powered devices can be connected directly to a solar panel and run. For AC powered appliances and devices, an inverter like the Renogy 2000W is required to turn DC into AC. That is basically how solar panels work. But what if there is nothing connected to it?
If there is no outlet for the power, the photovoltaic cells will just course the current into themselves. This will increase the solar panel temperature by a few or several degrees depending on the weather.
Is it OK to Let the Solar Panels Get Hot?
Should this be a cause for concern? Not really because the watt to surface ratio is about 150-180 watts per square meter. If you touch the solar panels you will feel the heat. But usually it is not going to be a problem.
A solar panel will not turn solar energy into direct current until there is a circuit. If there is no circuit, the solar panel will just “sit there” as the photons will not be converted into electricity. The panels will get hotter true, but the modules are going to get hot anyway if you connect a load to it.
What you have is a potential voltage, similar to a battery. The voltage will remain in the panels until you load. Of course when the sun goes down you can no longer use the solar panel power, not unless the energy was stored in a battery bank.
The situation is comparable to a battery. A fully charged battery – the Vmaxtanks 125ah AGM is a good example – can power several appliances and devices, but it must be connected to a load. Without any connection it is just potential energy. The same thing can be said for solar panels.
Is it OK to Leave a Solar Panel Disconnected?
Yes, solar panels can be disconnected without damaging any components. However you need to keep the following in mind before unplugging the panels.
Do not unplug the solar panels during daytime. Wait until it is evening just to be safe. The panels will always have power when the sun is out, so wait for nightfall to disconnect the system.
The larger the solar array, the higher the voltage and power. It is not different from any electrical component so exercise caution. Use a multimeter to check the voltage before attempting to disconnect it.
Follow the manufacturer instructions for unplugging solar panels. The steps will vary depending on the design, but usually you need to use a screwdriver to remove the wires. Once the cables are removed the panel is disconnected.
Is it Necessary to Unplug Solar Panels?
No it is not. Most solar panel installations are not disconnected once configured. There is no harm in unplugging the panels or turning it off, but it has few benefits.
The purpose of a solar panel is provide energy to power appliances and devices. If you disconnect the modules, you have to wait for the panels to collect and convert energy before it can be used. Depending on the weather this can take hours or days.
It is better to just leave the panels connected and draw energy. As we pointed out, it is all right to let the panels warm up even if there is nothing connected to it. And if you have solar panels installed it probably always has a load on anyway.
The only time it makes sense to disconnect a solar panel is if you do not plan on using it for a long time. If you are going on vacation for several weeks for example. Or you are expecting a snow storm or heavy rain for several days. In those instances you may opt to unplug the panels.
Batteries can also be disconnected. When you plug them back into the system the charge should be where you left them off. Provided of course you did not leave the batteries for too long. Batteries will self discharge eventually, so do not leave them unused for prolonged periods.
What Happens to Excess Solar Power Generated?
Solar panels always produce energy when the sun is out. The energy is used to whatever load is connected to the system, but what happens if your panels produce more energy than is consumed?
In a grid tied system, excess solar energy is sent to the grid where you can tap into it anytime. The more extra energy you send to the grid, the more credits you earn that you can use later on. This allows you to build up an energy reserve so when winter comes for instance, you have energy available.
In an off the grid system, the excess energy is stored in a battery. The amount of energy that can be stored depends on the number of batteries and their capacity . So you need to calculate how much solar power you use and how much excess needs to be stored.
If you are on a grid tied system you do not need a battery bank. The benefit of having batteries though is that in case of a power outage you have access to power. You cannot use grid tied solar panels because the power company turns them off in case of a blackout.
Whether you are on the grid or off it, there are ways to store extra solar power so it does not get wasted. All it takes is some planning and preparation.
Should I Cover Solar Panels When Not in Use?
This is another matter that comes up when discussing what happens to solar panels when not in use. Do you have to cover them or not? The answer is it depends.
Solar panels do not necessarily need a cover. You can leave them in the sun, rain, snow and they should be fine. However, putting covers on solar panels does provide benefits like keeping dust off.
Why You Should Cover Solar Panels
The biggest benefit of covering solar panels is to prevent dirt buildup. Suppose you have been using the panels all day. The sun has set and you switch to battery power. Instead of leaving your solar panels out there exposed to the elements, you can cover them.
Putting a fabric covering will keep dirt, dust, bird droppings, foliage and other debris off the panels. It makes cleaning easier and quicker. A clean solar system will produce more power which is what you need.
Solar panel covers are also useful during the winter. A bit of rain is not bad, in fact it is great for cleaning and removing dirt. But a heavy, continuous downpour might cause damage and water could seep in the cells. That could damage the panels irreparably.
Covers are also useful protection against snow. Removing several inches of snow is no fun, especially if you have a large solar array installed. By putting a cover on the PV modules you can keep the snow off it.
Why You Should Not Cover Solar Panels
However there are also good reasons not to put any cover on. If it does not snow or rain heavily in your area, it is better to just leave the solar panels as is. Some rainfall or snow every now and then is not going to cause damage.
Putting covers on and off can also be an inconvenience. Imagine you are in an RV. Having to go up the roof every day just to put the covers on and off is not practical. And a large solar array like those in homes cannot be covered up anyway due to their location and size.
Lastly, most solar users do not cover their panels because they are designed to handle different types of weather, heat, cold, rain, snow, dusty, arid, humid etc. Depending on your location, covers are probably not required.
Solar panels are not perfect, but they are among the safest power sources available today. As long as the connections and installation are done right and the system is not overloaded, you do not have to worry about something untoward happening.