The power inverter is a key piece of solar equipment and unlike solar panels, which are intuitive to understand (i.e. they soak up the sun), inverters can often sound like they will require a trip back to high school physics class. Understanding how a power inverter works requires putting meaning into the words “power” and “inverter.”
Generally speaking, the point of a solar panel is to create electricity through the renewable, limitless energy of the sun. That’s the “power.” But how do you get the power from the solar panel to your appliances?
The inverter is wrongly named. In practice, it’s more of a convertor, as its primary function is to “convert” battery power into AC current. Still confused? We’ll get there. If have any familiarity with car batteries, the inverter won’t be intimidating in the end.
Hooking an Inverter to a Battery
A standard inverter is measured in watts (e.g. 6000 watts) and will allow you to hook your battery – using battery cables – to the positive (red) and negative (black) terminals on the inverter.
The cables screw in easy so they stay snugly in place. The inverter itself is a little larger than a breadbox, and youtube offers tutorials on how to use all of its features.
Your battery, whether it is a marine battery, car battery or one designed for your solar system, will give you energy via a DC (direct) current, but this current isn’t useful for household appliances. It needs to be converted for the type of current we use: AC (alternating current).
Some inverters come with battery chargers, which is a helpful feature since anyone who owns a solar system will need to keep their batteries in good working order.
Automatic Transfer Switch
Power inverters include a switch that will automatically transfer (really, convert) the DC power from the battery into usable AC current. After the battery cables create the connection between the battery and power inverter, the “on” switch will make the power transfer happen.
How a Power Inverter Helps Support Your Solar System
The two most common types of solar inverters for general use are micro inverters and string inverters. The third type, central inverters, is used mainly for commercial power and large arrays.
This small inverter is built to attach to a single solar panel. DC current from that panel is transferred into AC current. The advantage of this type is the small size, and ability to transfer current even if the whole array isn’t functioning. The disadvantage is the higher price point.
This inverter style is used for efficient transfer from DC to AC, and string inverters are typically inexpensive. However, the problem with string inverters is they can present a potential hazard due to high voltage, and therefore might not be the best choice for someone just getting into the inverter game. They lack panel-level monitoring, but many homeowners and other users of power inverters choose this option due to cost savings.
How Do You Decide?
A powerful inverter – the kind favored by those off the grid—will run upwards of $2,000. A micro inverter, on the other hand, can start at as little as $75. Your best bet when weighing options is to consider how you use energy, what your long-term solar panel array will look like, and whether you have back up electricity.
Micro inverters work well for many systems, but if you are relying solely on solar power a higher wattage (over 3500) inverter is a good idea.
Stay wired (and safe), friends!