The Solar Power Inverter

The solar power inverter is an essential component for most home solar power systems.

Why is a solar power inverter needed?

Any home solar power system is based on solar panels. A solar panel is a combination of photovoltaic cells wired in series and in parallel that convert sun radiation (photons) into DC (Direct Current) electrical power. Conceptually, the solar panels are in essence a DC power generator.
Historically, power utilities provide AC (Alternate Current) power to the customers because AC power can more efficiently be transported and distributed. As a consequence, all electrical appliances and electronic devices that are used at homes and offices are powered by AC electrical power. The solar inverter task is to convert the generated DC power into a standard AC power (115V 60Hz in the US, 230V 50Hz in most other countries).

What are the different types of solar inverters?

The two main types are:

for off grid homes (homes that are not connected to the utility grid and that are autonomous)
for grid tied homes (homes that are connected to the utility grid)

The differences are in the way the inverter maintain the right AC voltage and frequency. A grid tied inverter must must include a protection to prevent the AC current to go back to the grid in case of utility power shut off (this is to protect the utility personnel working on the utility power lines)

What to consider when you buy a solar inverter?

You need to look into the following when you buy a solar power inverter.

Compatibility with the voltage rating of the solar panels (12V, 24 V or 48V), with the voltage variations incidental to the normal operation of solar panels and to current rating of the solar panels.
The amount of current ( and power, power rating is the voltage time current), the inverter is supposed to deliver to the AC consumers. In case the AC load require excessive surge current when turned on (such is the case with refrigerators, other appliances that has motors and plasma TV sets) the solar inverter must be capable to provide excessive short currents for short periods
The wave shape should be as sinusoidal as possible, the figure of merit is the amount of harmonics in percent . Buy what is called a pure sine wave inverter because most household appliances require a low harmonic distortion wave-shape.
Last and not least, watch for the efficiency of the inverter. How much of the generated DC power is actually converted to AC power and how much power is wasted and converted to heat. Top class high quality solar inverters exhibit better than 90% efficiency under most load conditions and almost 95% under “best” load conditions.