Probably the most important component in any home solar installation is the inverter. It’s also the most complex, which makes getting the right one essential in any DIY setup. We’re going to discuss inverters, what they are, and what to look for when choosing one for your home setup.

Essentially, a solar inverter converts DC current generated by solar panels into AC current used by appliances. The way solar panels work, by forcing electrons through a path to generate current creates Direct Current. It flows in one direction, as dictated by the panel.

The utilities provide AC current, so all our appliances need Alternating Current feeds. It’s used because it’s the most efficient medium to transmit power over long distances. Despite that, many appliances actually use DC for running, but are wired to convert AC to DC internally. So even though the appliance itself may use DC current, it still needs an AC feed.

To convert the power generated by a solar panel into usable electricity we need a solar converter. The type depends on where you’re going to use it. There are different models for homes, commercial properties, RVs and boats.

The first consideration is the voltage. In older systems, the standard was 12 volts. Newer systems use either 24 or 48 volts. The higher the voltage the lower the current, which makes wiring a system easier and cheaper.

The output needs to conform too. The standard utility service in America is 115 and 230 volts at a frequency of 60 Hertz. The solar inverter will need to match this if you’re using it in a building.

Next up is capacity. How much do you need the inverter to be able to handle? There are three levels of power rating. Continuous rating, a limited-time rating, and a surge rating. Continuous is the amount of power the inverter can handle for an indefinite period of time. Limited-time rating is a short burst of power for 30 minutes or so, and the surge rating is the ability to feed an inductive load of an appliance.

The capacity of the solar inverter must exceed the needs of the system. The continuous rating should be a little over the peak output of the solar panels, and the other ratings should also match. The specifics are out of scope of this article, but will be discussed another time.

The next important aspect of a solar inverter is the sine wave. This is what our appliance like to be fed. The cleaner the wave, the quieter our equipment. There are two types, modified sine wave, and sine wave. Modified sine wave inverters simulate a sine wave. They aren’t as efficient as true sine wave, and can have detrimental effects on sensitive equipment like computers.

Total harmonic distortion of the wave below 6 percent should be fine for normal home appliances. You need less than 3 percent if you have sensitive electronics, like servers or recording equipment.

There is much more to choosing a solar inverter as you can imagine. But these points are the most important ones. While price is a factor, you absolutely must have the right tool for the job first.

Solar inverters perform a vital role in any solar power system. They control the flow of electricity between the batteries and the building, modify the current from DC to AC, and charge the batteries if they need it.

This is of course ignoring the smaller inverters on boats and RVs. In their case, swap the word building for vehicle.

Solar panels harvest energy and convert it into direct current. Our domestic appliances need an AC feed in order to work. So that current needs to be converted in order to be of any use. That’s where solar inverters come in. Translating DC into AC is their primary task.

As we mentioned, it isn’t their only role here. In an average solar power system, the panels provide current which is stored in batteries. These then feed the house when power is required. The inverter is the middleman and makes sure the power gets where it needs to. It also charges the batteries if there is no sunlight.

You can think of the inverter as the gateway. It ensures the right current gets in and out of the solar power system. It also ensures the power provided is clean and in the right form.

While our appliances require an AC feed, they actually use DC. Each has a tiny converter inside to change the power back. We use AC current because it’s the best form in which to transmit electricity over great distances without significant loss. The AC wave can travel these long distances with relatively little wastage, whereas a DC current loses much more.

Solar inverters come in two forms. True Sine Wave (TSW) and Modified Sine Wave (MSW). A true sine wave inverter converts DC current into AC very efficiently. Their output is very clean with little distortion and is suitable for all appliances. A pure sine wave makes appliances run quieter and prevents voltage fluctuations. The instruments contained within convert the current within a much finer tolerance, resulting in this cleaner output.

A modified sine wave is a little rougher and doesn’t produce such a good quality wave. As a result it cannot be used with sensitive equipment such as computers, printers, games consoles and the like. It can also cause problems with rechargeable items. The inversion process is much the same, but the current isn’t converted to within such high tolerances.

The downside of a TSW inverter is the cost. They do cost more than an MSW, but the end result is a cleaner power feed, and quieter appliances. It’s possible to combine the two solar inverters into a system and have a TSW inverter provide power for sensitive appliances or equipment.

We don’t often equate the noise generated by our appliances with the quality of the power feed they receive. Generally, when part of the grid, the power delivered to our homes is of a high quality so it doesn’t become an issue.
If cost isn’t a consideration then a TSW inverter is definitely the way to go.