If you are going solar for your home or business, it is important you know why and how to wire solar panels in parallel. Mark just switched to solar energy as an alternative energy option. With all the talk about renewable energy and climate change, he decided to ‘go clean and green’ with his home energy supply. He is finding it quite confusing to understand how to install the system in his home. Mark isn’t sure he needs to learn how to wire solar panels in any specific way: parallel or series. This is because to him, once the connection provides electricity, it’s all good. But is it?
Well, I‘m so not sorry to burst Mark’s bubbles, and yours too if you think the same way. How you wire your solar panels matters. It is one of the most important variables in your solar energy system. It determines the overall efficiency of your system and also affects the kind of equipment you would have to buy alongside it. For one, your choice of inverter is based on its current and voltage rating depends on how your solar panels are connected: series, parallel or both. I’m sure you want the best option for your home, right? This is why you have to take note of this.
For those who are still in the dark as to what solar energy, solar panels, inverters and all the jargons we have just discussed, no worries. I got you. Let’s take a run down through the basic concepts. Shall we?
Solar energy is the most available energy source on earth. It is clean, renewable and cannot be used up. Solar energy is increasingly being integrated as an off-grid energy option in homes and offices. This is well in line with the Sustainable Development Goals for 2030, which targets a substantial increase in the share of renewable energy in the global energy mix as well as an improvement in energy efficiency globally.
A Solar panel is a very important component of the solar energy system. It is responsible for trapping sunlight and converting it into electrical energy. The panels are made of Photovoltaic cells or PV cells. They are spread about on the surface of the panel boards. When sun rays fall on these cells, they are converted to electricity. So, the more the panels, the more PV cells are available to generate electricity. This electricity is Direct Current (DC). However, most of our commonly used electrical equipment make use of Alternating Current (AC). An inverter is then connected to the solar panels. Inverters are electronic devices that convert DC to the required AC needed to power electrical devices. So, we have our needed current and so our system is set up, or is it? There is still one more thing.
We also need batteries in our system. Since we do not have the sun in full intensity at every time of the day (of course night comes and the sun retires to bed), we cannot guarantee that we would always be able to constantly produce a certain amount of electricity. Also, during cloudy days and also in the winter, the many clouds that form in the sky reduce the intensity of the sun reaching us. This means that much electricity can be generated from our solar energy option. This is where batteries come in. Batteries help us store the energy generated for future use. During the day when the sun is at its peak, you can use electricity in your home and be rest assured that by night, you’d still have electricity running so you can continue from where you left off the Game of Thrones episode before work. I see it like a kind of savings account or piggy bank, where you save energy for the rainy day (pun intended).
To increase the efficiency and power output of your solar energy system, it is advised that you buy more solar panels. When you have more solar panels, the ideal thing to do is to connect them. This is pretty much obvious. Now here’s the catch. Well, panels are not connected in just any way. All the types of connection are aimed at achieving one main purpose: to increase power output. However, each method employs a different strategy in doing this. We will see this as we proceed.
There are three ways solar panels can be connected:
What does a series connection mean? Well, whenever electrical components are connected in series, the aim is usually to increase the voltage of the circuit. Solar panels connected in series produce a combined total voltage of the sum of individual panel ratings. What this simply means is that if you have six 12 volts 5 Amperes panels connected in series, your total output would be 72 volts 5 Amperes (Amperes is the unit used to measure current).
Series connection creates a single pathway for current to travel, which means that all the current must flow through all the loads (in this case the solar panels) in the circuit. This is why the current remains the same up to the output. One other characteristic of series connection is that when the circuit is cut at any point, the entire system stops operating. This is pretty much expected since the same current goes through all as we have seen, so cutting off one is stopping current flow in the circuit.
Solar panels have negative and positive terminals. To connect panels in series, you connect the negative terminal of one to the positive terminal of the next. This way you can increase power without altering the value of current being fed into the inverter. A very common example of series connection is your TV remote control. Also, a string of Christmas lights too is connected in series. The lights would not come on if one of the bulbs is burnt or not in place. Current path, remember?
Parallel connection, on the other hand, provides multiple pathways for current to travel within the circuit. This is the most common of all types of electrical wiring. I’m very sure your house is wired the same. Want to know how? Your home has a primary point where electricity enters into the house. It is from this point that electricity is fed to different sockets, bulbs, heaters in your home. When your friend comes visiting and you turn off the microwave after heating your lunch, it does not also turn off the TV in the living room. Like we saw in series connection, one point in the circuit going off means the entire circuit goes off too. This is not the case in parallel wiring. Since we have multiple current paths, one path going off does not affect the other(s). This means that parallel connection allows for redundancy, that is the system is more reliable as a fault in one path does not affect the whole.
Aside from improving the reliability of systems, parallel connections also aim to increase the amperage at the solar panel output. This means more current is being fed to the inverter. So, taking our example of six 12 volts 5 Amperes solar panels, parallel wiring would produce an output of 12 volts 30 Amperes. If a consumer has an inverter with a DC input rating of 12 volts, then such consumer only needs to supply 12 volts from the solar panel for the inverter to function. In this case, the consumer can connect in parallel to increase the amount of current, since the panels are wired to feed in 12 volts. This way, power can be increased without going past the voltage limit of the inverter.
Mike and Tim live together and have decided to get a solar panel. They split the bill and both agree to buy two panels each when they return from work. Later that evening, they discover that they have bought dissimilar solar panels. There has been an argument all evening, and it looks like work was tough on both of them. Well, I can help.
If you are wiring similar solar panels in parallel, it is pretty much straight forward. You connect all the positive terminals together into one terminal and all the negative terminals together too. So, I could convince Tim to go back with his and get one that matches Mike’s and then, case dismissed.
If Tim is hell-bent on keeping his, and Mike is not bending, they have science to thank that they can reach a compromise. When solar panels have different wattage but the same voltage, they can be connected in parallel. Wattage just means how much power is measured. If the voltage is constant, we can connect them just as we did the first instance. What that simply means is that current is the variable factor in the different panels. For parallel connection, once the voltage is the same, we are good to go.
Had they each bought panels with different voltage ratings, well one person would surely have to give in because there is no way we can connect them in parallel.
Well, Tim and Mike’s case didn’t fall into any of my predicted events. Tim bought two 6 volts solar panels while Mike got two 12 volts panels. Well, science to the rescue! We can connect the two 6 volts panels in series to get a 12 volts output. We can then connect this result to Mike’s 12 volts panels and everybody is happy. This is called compound wiring of solar panels.
It is important that you as a home or business owner are able to connect your solar panels yourself and understand what each type of connection entails. Parallel connection is the most commonly used type of connection and we have seen why. You can now make informed choices based on what is available to you and enjoy your solar energy option with maximum Returns On Investments (ROI).