Solar inverters plays a critical part within any solar power system, because it’s the device that turns the sun’s energy into high voltage energy you can use around the house. If you don’t have the right inverter then you’re not going to be happy with the output of the solar panels. Inverters come in different shapes and sizes, but there are 4 main types, which is also what this article will be looking at.
Central Solar Inverters
Starting with central solar inverters, these are probably the most common in South Africa. It’s important to point out that not all solar systems work with a single converter, but these will be discussed a little later. In this case it’s a standalone unit with the right capacity to carry all the panels. To give you an idea of what you need to look out for, a house with 10 panels requires an inverter that can handle at least 2.4kW.
Over the years the design has changed and several issues with this particular inverter have been addressed. For example, modern designs typically come with circuit breakers, string monitoring and even advanced output efficiency that easily reaches 95%. With string monitoring an isolated incident won’t have an effect on the rest of the panels. With older models a singular panel problem could lower the whole string. But now, if something is causing one panel to be less efficient, it won’t bring down the rest.
Central inverters can be used in residential and commercial settings, but you’ll also find some utility grade models for small scale purposes. Here is the breakdown of the benefits for central inverters.
Compact in size and not too heavy
Typically has an efficiency level of 98%
Very durable if bought from a reputable manufacturer
Usually comes with a touch screen display
You don’t see too many of these, but they are out there. As the name suggests, micro inverters are much smaller in size and capacity. They go up to about 300kW and are used on a single panel. Many manufacturers combine these inverters with panels before getting them out on the market. This way customers won’t have to worry about additional costs or installations.
Apart from saving time and money, micro solar inverters come with an array of other benefits. For example, the efficiency of the entire system can be monitored with more accuracy, seeing as each panel has its own converter. You’re also less dependent on the durability of the converter, because if one breaks the others will keep working. With a central converter everything goes down if it breaks.
There are manufacturers that claim the efficiency of micro inverters outweigh all the others and their life span can easily reach 25 years. Unfortunately it’s not such a big market in South Africa yet, so the pricing might be a little high. Here is a summary of the main benefits:
Easier and safer to install
Better monitoring capabilities
Panels can easily be added and removed from the system
If you install solar panels you have the option of connecting groups of them in series. This will improve output, but if one fails it effects all the panels in the string. String inverters are for systems like these. Each inverter gets connected to a series of panels, then the inverters lead to a single output source through a combiner. One inverter can typically handle anything between 4 and 10 panels and thanks to the connected amount of power, it can be used for residential and commercial purposes.
Newer models usually don’t use transformers, a device that was prone to fail inside older models. You can also expect improved protection and built-in monitoring systems. The only real downside to using string solar inverter is the danger of the high voltage. Even though a low current can be just as dangerous, string inverters can easily produce a 1500v shock. Here are some of the unique benefits you can consider.
Provide a great amount of power
Typically have more than a 95% efficiency level
Additional strings can easily be added
Can be used to send power back into the grid
There’s no need for an oversized singular inverter
Several of the above mentioned models come with a grid-tie feature, but if you are looking for something more specific in terms of staying connected to the grid, look at your options in this category. Everything is going to depend on how much solar power you plan on using throughout the day. For example, if you only plan on using a small amount with the hopes of bringing down the electric bill, you can use a utility scale inverter. If you think you’ll have some energy to spare and you want to feed it back into the grid, simply get a larger converter.
Unfortunately South Africa doesn’t compensate households that feed energy back into the grid, so it doesn’t really make sense economically. You’ll be better off investing in some batteries and storing the energy.