Given the popularity that solar power is beginning to gain around the globe, we must consider all of the practical aspects of having a solar unit at home, and this includes taking care of your solar power setup and all of its parts. Your solar inverter in particular is at risk of damage by the elements, and lightning poses a big risk here. Of course, before we get onto how we can protect our solar inverter, let’s brush up on what a solar inverter is first.
Your solar inverter, like a normal electrical inverter, plays a very important role in the process of supplying us with electricity, so it is a main piece of equipment. All of your electrical appliances make use of alternating current (AC), and electricity is normally produced with a direct current (DC). This is where the inverter comes in and essentially converts the direct current (DC) into alternating current (AC), so this converted current can then be used to power our homes and appliances.
Thanks to modern innovation and technology, there has been a lot of advancement in the field of inverter technology. Now, an inverter’s job is not just limited to converting direct current to alternating current, as there are many other features and options added to it as well.
Inverters can now come with utility controls, data monitoring systems, and so on. All of these functions can optimize the way we use our inverters. Now the prices of solar power units have been dropping, and this price drop has led to innovators being more creative with their products, so they will try to fit in different features, and at the same time, they will try to figure out which areas they can save money on and so on. The one thing everyone has been keeping in mind when buying or designing their inverters or other parts is the ease of manufacturing since this can help to cut down extra costs and make it possible to produce good inverters at a lesser cost and be able to sell it at a reasonable price to customers as well.
Our electrical grid is old and will be considered obsolete in another century or more. Given the popularity of solar power, companies now need to ponder over the impact of high photovoltaic (PV) penetration might have on our electrical grid, and the solution seems to lie in our inverters.
Inverters come with features like utility controls, system monitoring, etc. so an inverter might help distribute the PV better, and will help you control the stream of electricity that enters and then gets distributed into the electrical grid. This can help electrical grids incorporate solar power without having to bring about too many major changes in infrastructure and mapping.
Solar Inverter Types
We have already concluded that all inverters help to accomplish the same task, which is to convert solar direct current into solar alternating current so that you can use it in your homes. However, there are still three different types of solar inverters, and we will be going through each of them so that you can make a better-informed decision.
You will find string inverters or centralized inverters being used in small-scale solar powered units and systems. Like the name suggests here, when it comes to a string inverter, every panel is wired into each other together like strings. When energy is produced by your solar power unit, all of it travels to the inverter which will then start working to convert all the electricity that came from the solar panel into alternating current (AC) electricity for use.
String inverters are the best choice of inverters for houses that have a simple roof where there is direct sunlight exposure throughout the day. Plus, it works well for families that have a more restricted budget and are not looking to spend too much on their solar setup.
If we talk about the positives, then:
- String inverters are the cheaper inverter option out of the three.
- It is consistent in terms of its performance.
- Their maintenance is simple and easier since it is usually in a more accessible location on the roof.
If we talk about the negatives, then:
- Your string inverter is only as strong as your weakest panel. So, your string inverter produces as much electricity as your least efficient solar panel.
- Your entire inverter’s performance and efficiency can be affected even if one or two of your solar panels are in the shade or obstructed in any way.
Power optimizers can be considered as a happy compromise between microinverters and string inverters. Power optimizers are usually located either next to each solar panel or are integrated with them. However, kind of like string inverters, power optimizers will also send all of the energy that is produced to a single centralized inverter. Power optimizers will not convert DC into AC electricity at the solar panel, so they instead stabilize the electrical voltage and then send it down to the string inverter, creating a more efficient system.
- Power optimizers help to increase and improve the overall efficiency of the solar panels system.
- They are more expensive than string inverters but at the same time, cost less than microinverters do.
- You can monitor the individual performance of every solar panel and then optimize accordingly, and even if one or two panels are underperforming, it will not drastically affect the overall output efficiency.
We will now move onto the main subject of this article, which is what we can do to protect our solar inverters from potential lightning.
A lot of people are unaware of this, but lightning is responsible for a good chunk of serious electrical failures and damage to solar electric components and systems. The reason why this happens is that our photovoltaic systems are poorly protected and are not properly grounded.
Lightning Protection Explained
Lightning protection does not mean that you can stop lightning from happening or striking your solar electric system. Lightning protection entails controlling the direction lightning takes after it does strike your system. The lightning itself does not cause damage, and the damage it causes is large because of the places and parts the lightning travels to after it strikes the system and setup.
This sounds crazy to envision, but at a single moment, at any time, at least 2000 thunderstorms are happening in different areas around the planet. Lightning travels at half of the speed of light and is also known to be 100,000 times faster than the speed of traveling sound. Another interesting fact about lightning is that it likes to strike on land mostly.
Of course, lightning protection will not offer complete protection, but it can still significantly reduce the extent of the damage that can be caused, so a few simple steps and additional work during installation can help you in the long-run.
How to Protect Your Solar Power System
The National Electrical Code is not always correct, and some believe that it does not provide enough protection in the case of off-grid solar system installations. However, you still have to abide by those rules since it is the handbook that our inspectors follow.
Lightning can be unpredictable but the NEC believes they have lightning movement and behavior down like facts, which is not the actual case. However, there are additional steps you can take apart from abiding by the NEC’s regulation. NEC grounding does not work in regards to lightning protection, so you will have to take over from there. If your solar inverter and overall setup are not properly grounded, the lightning will be moving around all over the place in its attempt to get to the ground.
Mounts and solar panel frames can all prove to be incredibly useful since they will help the lightning find a quick path directly to the ground. Lightning should be traveling through the mounting pole or ground rod as opposed to your inverter, controller, wiring, or other parts of the solar system.
Are Breakers & Fuses Useful?
Well, fuses are circuit breakers are useful in general, however, when it comes to protecting your system against lightning strikes, the answer is no.
There is a myth that your fuse or circuit breaker will protect against lightning, but that is not the case. Lightning only lasts a few microseconds, and no fuse breaker can handle such a large surge of energy in such a small time.
Single Point Grounds
All of your solar panel components and equipment should be bounded to a good specified area of the ground. This cannot be stressed enough, and you must understand this. If some of your solar equipment is placed in one section of the ground and the other is placed in another area on a different ground, then any lightning strike nearby will affect the voltage in the two ground differently. So, if one area gets a high enough voltage, then it can move, travel, and affect the other. So single-point grounds for your equipment is a necessity and should be something that you always go for during your installation.
One Ground Rod is Not Enough
One ground rod is not enough to handle a lightning strike, and this happens in situations where the soil chemistry is different. In areas where the soil is too dry or too salted, one rod will not suffice. It can take anywhere between 2-20 rods depending on the grounds level of resistance. For example, if you want to reach the 25-ohm level (which is the minimum requirement as per the NEC), you will need anywhere between 2-4 rods that are like 10-feet tall. These rods will also need to be bonded together with wire, and proper copper wire clamps. It seems like a lot, but you can get this done during the installation process and this extra step will end up going a long way.
Grounding: A Potential Option
If you want to look into grounding as an option, then you will need a separate, large conductor that needed to be fastened or bonded to every metallic module frame with either a grounding lug or any other method that is NEC approved. The opposite end of the conductor needs to be connected to either a rack with a stainless steel screw that is self-threading or a bolt that is made of stainless steel that comes in a tapped and drilled hole, or you connect everything to a single spot of the array frame.
A large copper conductor should pass into the ground where it can be connected to the longest, most penetrative rod that you can afford at the time (8 feet is the minimum and most recommended). In case you used a steel well casing, then you can tap and drill the casing, and then use that as your main ground rod.
If you happen to live in a dry area, then you will need to place some ground rods that are placed 20-25 feet apart and then bonded together to the main rod as an effective measure.
Copper Wires & Pipes
Another way you can improve your overall grounding system is by burying copper wires or pipes in the ground in a trench. You can make 12-18 inch deep trenches in a radial grid style and bury the wires or pipes in there. Do not solder the underground connections, and make sure that all of your grounded members are either bonded or connected to the main, central ground rod, and you have to be mindful that the bare and heavy conductors are buried underground as well.
This will not create a perfect ground, but it will make a good one that can still be useful for you if there is a lightning strike since it will significantly bring down the damage. However, if you do want to create perfect ground conditions, you will have to be willing to spend a lot of money to dig and bury copper cables.
You cannot undervalue the importance of good ground. If your surrounding earth is dry, arid, or rocky, then this can prove to be a challenge. You do not have to aim for perfect ground conditions (because that is impossible most of the time), but you can still improve it. Salting the area around the ground and dampening the soil can help. You can also bury copper pipe or wire in ditches to help as well.
We have managed to discuss several ways that you can go around and protect your solar power unit without worrying about lightning damage. Yes, these may not be able to protect your entire system entirely, but it can definitely help with damage control and can also help reduce the likelihood of ruining your otherwise very costly investment. So these simple, extra steps that you can take during and after the installation process can prove to make a world of a difference.