A solar inverter, also known as a photovoltaic or PV inverter, transforms the direct current (DC) electricity produced from solar modules into alternating current (AC) electricity needed for home appliances. Choosing an appropriate solar power inverter depends on:
power output of the array
whether it is grid-tied or off-grid
incoming electrical service (if applicable)
Photo Credit: Los Angeles Solar
For a grid-tied system, you must ensure the inverter transforms DC to AC that matches the characteristics (voltage, phase, frequency, and sine wave profile) of the electricity of your local grid. You can contact your power provider to find out which models of inverters are suitable for your grid.
An off-grid system has the added complexity of batteries, and often a generator. The main factors for an off-grid inverter is the amount of load to be supplied on the AC side, generator connections (and size of generator to be connected), and available incoming DC power from the charge controller.
When sizing your solar panel inverter, keep in mind any future expansion of your PV system. It is often cheaper to get a bigger inverter than to replace everything later. Each manufacturer has a full line of inverters to match any sized array. Literature on sizing is usually available on a manufacturer’s website.
These are connected to each individual panel. Using micro-inverters allows almost full generation of energy even if one panel in the array is shaded. Any problems with a single panel are isolated and do not put the whole array out of commission.
The initial installation is simpler, as is the future addition of more modules to an array. With monitoring technology, pinpointing problems is fast and easy. However, with the inverter(s) on the roof, reaching the problem might be more difficult than if the inverter was down at ground level.
Some claim that micro-inverters are in fact more durable than central inverters because they process smaller amounts of energy – that is, the combined energy output is divided between multiple inverters, meaning each inverter experiences less stress from use. The leading brand of micro-inverters has a warranty of 25 years.