We have spoken much about solar panel inverters over recent weeks. Partly because of their importance, and partly because they can be complicated. Specifying a solar power system is relatively straightforward. You calculate the peak load of the property, add a percentage, then choose enough panels of the type suitable for your location.
The panels have a specific wattage, batteries have a specific capacity, and the overall system is pretty straightforward. Things aren’t so simple with a solar panel inverter though. Should it be grid-tied or not? Sine wave or modified sine wave?
Today we’re going to discuss the sine wave. It’s a term that not everyone will be familiar with, yet is important to know when choosing a solar panel inverter.
A sine wave is the alternation of electrical current that makes up AC power. Think of a pendulum, that ticks back and forth in a constant, predictable fashion. That’s how electricity flows through the grid into your home.
The electricity is fed to an alternator which ticks back and forth creating the wave. It rotates at 60Hz and as it ticks, spilling forth electricity, the sine wave is created. The more exact the wave, the more efficient the appliance that uses it.
These waves have been found to be the ideal transport mechanism for electricity. The wave travels distance very efficiently, and with minimal loss, which is why our grid uses AC power. In reality, most of our appliances actually use DC power. Each contains a small inverter to convert AC to DC internally in the appliance.
A solar power system generates DC current. The panels collect the energy and directs it through a system of channels, which is how direct current is generated. That power is fed to the batteries, which also use DC power.
The job of the inverter is to take that power from the batteries and transform it into AC which our homes can use. That’s where the complications begin. We mentioned the two types of sine wave, true and modified. A true sine wave is a much cleaner signal and is more efficient than a modified wave.
Solar panel inverters that generate true sine waves are more expensive than modified ones. If you use a modified sine wave inverter, you many notice your appliances are slightly noisier than they were before. That’s a by-product of a “dirtier” wave. It just means the wave isn’t quite as exact as a true one, so makes more electrical noise, which is transmitted through the appliance.
Anyone with computers, servers, sound recording equipment and other sensitive electrical devices will need to use a true sine wave solar panel inverter. The modified sine wave inverter isn’t clean enough to reliably power these kinds of devices. It has been known for them to damage sensitive gear.
For the rest of the household appliances, a modified sine wave inverter is fine. The devices will be slightly louder, and slightly less efficient, but not as much as you would notice.
Choosing a solar panel inverter is about getting the right device for the application. Not everyone is going to need to spend the extra money on a true sine wave inverter, but those with the devices mentioned above should. It’s possible to use both kinds in a system, as long as the feeds from each go to the right places.