You have two choices when you want to wire multiple solar panels in a system. You can either choose to have them in series or parallel wiring. This mainly depends on the application you choose to go with.
What’s the Difference? Series vs Parallel
The output voltage and current are the main differences between series and parallel. In series, the output voltage of your solar panels adds up. The current output, however, remains the same. Panels in parallel wiring have their output currents adding up. However, the output voltage remains the same.
Series Solar Panel Wiring
In series wiring, you should connect the positive terminal on the first panel to the negative terminal on the next panel. The end result will be voltage that adds up to all the panels in the series. The total current will be the same as that of one panel.
Solar panels arranged in series are great in places with no shade. Each panel should receive enough solar energy. If one is covered, the whole system will not work optimally.
Parallel Solar Panel Wiring
In parallel wiring, you should connect all the positive terminals on each panel. Next, connect all the negative terminals to each other. The current will be from the total of the parallel array. Your total voltage will be the same as the output voltage of one solar panel.
When you arrange solar panels in parallel wiring, each panel will function on its own. In case one is covered in shade, the rest will continue to generate solar power.
Using parallel wiring is great for a low voltage system that has a lower-cost PWM controller. It will not alter the total output voltage, but you will always have power.
Comparing Series and Parallel Wiring
Are you considering solar panels as your power source? Do you want the wiring done in series or parallel wiring? Do you know which is better for you? The decision on wiring is important when installing solar energy. It totally depends on the application you plan to have.
When you use series wiring, you should consider whether you have an unshaded location. Your solar panels will need as much exposure to the sun as possible. This will ensure they are effective in providing solar power. In series wiring, your power will perform better in the mornings and evenings. It will also be great on cloudy days.
This is because batteries can only charge at a voltage that is higher than their nominal voltage. Lithium batteries often require about 14.4 volts to charge. A lot of 100-watt solar panels give an output voltage of 18-20 volts. To charge batteries at 14.4 volts, your panels should operate at more than 75% capacity.
If you have three solar panels arranged in series, you would get a maximum output of 54-60 volts. Your solar panel array will operate at 25% capacity for your batteries to charge. Achieving a 25% capacity, even on a cloudy day, is easy. However, for a system like this to function properly, you should get an MPPT charge controller.
When you use parallel wiring, you do not need an MPPT charge controller. They are expensive and quite unnecessary for small portable applications. For low voltage systems like on a boat or RV, you can use parallel wiring. It is a great option for applications of smaller sizes. You can use it if your solar energy is for variable lighting conditions. A boat or RV can use a lower-cost PWM charge controller. It also saves a lot of money to use this option.
Series or Parallel for Mixing Panel Types
The examples we have given above have assumed your wiring uses similar solar panels. This is usually what is advised. It is, however, not the only required method. You can mix solar panels that you buy from different manufacturers. You can also use solar panels with different electrical ratings. When mixing solar panels, there are important guidelines to consider.
When you use series wiring on your solar panel array, you should have panels with the same current rating. The voltages will add together as normal. Your current output will depend on the panel that is rated lowest. This is what your output will be.
When you use parallel wiring, all the solar panels you use should have similar voltage ratings. Your system output voltage will be the same as the panel that gives the lowest voltage rating.
It is advised to use the same solar panels in every solar panel array on a charge controller. If you want to optimize energy by mixing solar panels, you should consider multiple charge controllers. These can be placed on each solar panel array. It will help to increase the solar output to the maximum.
When deciding which solar panel array to use, a trained professional should be able to help. Both series and panel wiring have their advantages and disadvantages. Depending on your needs and application, you should be able to narrow it down to one option.