Microinverters

A microinverter is a small inverter mounted directly under its designated solar panel, one per panel. So the electrical energy coming off the roof is AC, already converted from the DC production of each panel working independantly. The outputs are paralled up and fed to the home c/breaker board and combine with mains power to share the electrical load. This is one of two aspects this system shares with the grid-tie installation, the second one being the lack of battery connection. Where they differ in concept is that this installation will keep operating without any grid connection.

The benefit of this system is that it overcomes the problem of shade falling across part of an array and causing a degradation in the array’s output, or where there is insufficient mounting space for a powerful enough string of panels. Each panel is operating independently and is not affected by the shading or layout orientation of any other panel. In terms of a future expansion of solar power the addition of a few microinverter/panel units will not require any reconfiguring to the balance of a solar voltage to inverter input voltage requirement ratio. 

A fault in any item won't affect the overall performance very much and the system monitoring should detect where the malfunction is making its replacement a relatively simple matter. The cost effectiveness of this system vs a grid-tie one is an issue that should be discussed with the installer, the initial costs of this are higher but the replacement cost of a single faulty inverter is less. On the other hand it may be easier, and therefore less costly, to replace a wall mounted string inverter.