Inverters

In the very early days of solar, many people used RV equipment designed to work on 12VDC power. This direct current was that available from common auto or marine batteries that received the wattage directly from the photovoltaic (PV) panels themselves. They were trying to save as much money as they could while utilizing as much of the solar energy they were able to harness in those early, inefficient systems.

Today’s inverters are far more efficient than the early ones that cost hundreds of dollars when they were first manufactured for solar use in the 1970s. While inverters remain one of the more expensive parts of a PV system (after the panels themselves and batteries), they are absolutely necessary if you want to use your existing electronic equipment.

Many early types of inverters, known today as stand-alone inverters, were made for a specific application and attached directly to the power input of a single device. These are very common today in industrial or agricultural PV systems. They may be attached to lights, pumps or even a refrigerator. This type of inverter is always less expensive because the power that’s output doesn’t need to be as well conditioned or fed to a larger electrical grid.

A stand-alone inverter may be used in small applications such as powering a laptop up to 8,000W industrial applications. If used with high current applications, be sure the inverter is equipped with sufficient surge protection to avoid blowing it up when you unplug or turn off the device.

Grid tie inverters (also known as synchronous solar inverters) are the type most commonly used by those who wish to power any piece of equipment in the house. They are required if you want to sell current back to the power company – literally running the meter backwards! These are capable of taking input from the batteries and injecting the power back into the electrical grid or system that already exists in your home.

Such inverters are generally more expensive, but of far more use to the homeowner who wishes to supplement the power rather than spend a great deal of time and effort calculating maximum and average power loads for each device in your house. They allow for the solar generated power to be used first, relying upon outside power only when necessary. While they tend to be a bit more expensive than other types, they are far more useful to most homeowners.