The basic purpose of a solar inverter is to convert DC into AC. To explain the difference, DC (direct current) is the type of current foundoperating in a car battery while AC (alternating current) is the type of current found operating in a residential home connected to the utility grid.
Because solar photovoltaic panels only produce DC current, you need to have a way to convert DC to AC in order to operate the appliances in your home; thus solar inverters were created to bridge this gap.
If you’re planning to install solar photovoltaic panels and the electricity used at your home is supplied by the local utility, then a grid-tied solar inverter is the type you need. When the sun is shining on your panels, the inverter allows the direct current produced to be converted to alternating current and pushed back onto the local utility grid. And during times of cloudy weather or darkness, the electricity needed to power your home will be provided by the utility.
In properly designed and installed systems, homeowners can sit back and watch their meter spin backward through a process called net metering. Have you ever heard of people selling electricity back to the power company? Well, this is how it’s done; during times when your solar photovoltaic system is producing more power than your house can consume, the extra power is sent back onto the grid for someone else to use and you end up getting a credit on your bill.
Solar inverters of this type are less common but are likely to be what people think of when considering solar power. For people planning to own a cabin or home far removed from any electric utility connection, off-grid or stand-alone solar inverters are the way to go.
Off-grid inverters are more complex to install and operate than grid-tied inverters; not only is it required to change DC to AC, but it will likely be required to charge batteries, provide power to loads, and allow a generator connection. Because of the cost, complexity, and additional maintenance involved, those considering an off-grid system would be well advised to properly educate themselves before installing such a system.
Solar Inverter Considerations
New technologies are constantly being developed in the area of solar inverters. With constant monitoring, micro-inverters, and increased life-spans, choosing the right inverter can leave many confused. The following is a list of three things I would consider when purchasing an inverter:
- Warranty – Because solar inverters are the proverbial weak link in any solar photovoltaic system, make sure the manufacturer offers at least a 10-year warranty and that they stand behind it.
- Expansion – If you’re planning to expand your solar photovoltaic system in the future, prepare to spend a little extra money on an inverter that will accommodate the additional power production.
- Bells & Whistles – Although most of us want to use the latest and greatest technologies, some of these features are unnecessary for your particular system. Remember, whenever you add a new component to any product, it increases the chance of system failure.
So stick with the solar inverter basics; both your wallet and system will thank you.
What type of solar inverters are you considering?