A solar inverter or PV inverter, is a type of electrical converter which converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network.
As well as converting DC to AC, inverters also carry out a number of other tasks, too. For example, they can also act as data monitoring devices or advanced utility controllers and are power optimizers.
Most electrical devices run off AC energy. So, if you didn’t have an off-grid inverter to transform that DC energy harvested from the sun, you would be unable to power any of your electrical devices and the harvested energy would go to waste. That’s what makes a solar power inverter is an essential piece of any solar power system.
Different types of solar inverters
There are different types of inverters available for solar power systems, such as off-grid inverters, grid-tie inverters, pure sine wave inverters, and modified sine wave inverters. Ultimately, they all have the same end goal of converting DC solar energy into AC energy that can power your appliance, but the way in which they function differs slightly. The one that’s best for you will depend on a number of factors including what performance you need and how big your budget is. It goes without saying that the most powerful of solar inverters are the most expensive. But, if you don’t need one quite so powerful, why spend the extra money?
Most solar power kits will already come with an inverter included. However, if it doesn’t, or you’re looking to upgrade your existing one, here’s a brief overview of each type:
- String: This type of inverter is often referred to as a centralized inverter and is primarily used in small-scale solar power systems. With a string inverter, each solar panel is connected together in strings. When each of the strings produces energy it all gets sent to the inverter, ready for it to convert into AC power. String inverters have been around a long time and are a tried and tested form of technology. They’re also the cheapest to buy and the easiest to maintain. The downside to having a string inverter in your solar power system setup is that it will only harvest as much energy as its least efficient solar panel. This type of inverter tends to work best on roofs that get a consistent amount of sun during the day.
- Microinverter: As mentioned above, all inverters do the same thing, they just go about it a slightly different way. With a microinverter, instead of sending the solar panel’s harvested energy to the inverter via strings, these systems convert the DC energy to AC energy right there at the site of the solar panel. The advantage of using microinverters opposed to string inverters is that they’re far more efficient and will continue to produce electricity even if some solar panels are not performing as well as they should be. The downside is that they’re far more expensive to buy initially and tend to cost more to maintain and repair as they’re located on the roof. This type of inverter would work best with solar power systems that face different directions, are quite spread out, or have objects such as chimneys or gables that could cause shade.
- Power optimizer: This is essentially a compromise between the old faithful string inverter and the more modern microinverters. As with microinverters, power optimizers sit either next to or within the individual solar panels. However, unlike microinverters, they still have to transmit any harvested energy to a centralized inverter. The unique thing about power inverters is that they fix the voltage of the electricity before it gets sent to the inverter. String inverters become far more efficient when paired with a power optimizer and will still cost less than microinverters. Like microinverters, they will still run efficiently even if some of the panels are underperforming and can be used to monitor the performance of individual panels. Typically, power inverters are great for anyone who wants to improve the efficiency of their solar power system but isn’t ready to upgrade to microinverters just yet.
Hopefully, you will now be much more clued up as to what a solar power inverter is and the way it works. Now it’s simply a case of deciding which type will be best for you. Once you’ve figured that out, you’re good to go. Here are a few helpful tips to help you do that:
- Cost. Obviously, the price of the inverter will vary depending on the type you go for. Just bear in mind that an inverter can typically represent around 20% of the total cost of the system, so is not going to be cheap. And don’t be fooled into buying the cheapest one you can find. You get what you pay for when it comes to inverters and unless you want to replace it every couple of years, don’t skimp in this department.
- Is it expandable? If you are considering expanding your solar power system in the future you want to make sure the inverter you buy will allow you to do that.
- Warranty. A decent inverter should last a good 10 to 20 years. While most manufacturers won’t guarantee them for that long, most will cover them for at least 8 years. Be wary of any that are offering less than this.