Inverter Introduction

Inverters convert the DC power generated by solar modules (panels) into the AC power that is fed into the grid.

There are 2 types of inverter technologies, micro inverters that convert the power at each solar module and string inverters that convert the output from a number of modules that are wired (strung) together.

String inverters have traditionally been less expensive than micro inverters, so they have been the choice from a price point perspective. The problem with string inverters is that they have been connected to the modules in series and the entire string's production is automatically reduced to the level of the poorest producing panel. If one module in the string produces nothing (is shaded or faulty) the entire string output is reduced to nothing by the inverter. New technology however has modules being connected in parallel, where the entire string's production is the sum of each modules' production. This allows the maximum energy to be harvested by the inverter. String inverters are typically used in larger FIT sized systems (over 10kW).

Micro inverters convert the production of each module to AC, thereby maximizing the production of each module. Micro inverters also convert a smaller amount of energy more efficiently. This can produce solar harvests by as much as 25%. In addition, faulty inverters or panels can more easily be identified and repaired. Micro inverters also offer the ability to monitor production, online in real time on a panel by panel basis.

OntarioPVPower sells both string and micro inverters:

Enphase Energy Micro Inverter - currently manufactured in California although rumors suggest that they may open a plant in Ontario by 2011.
Sustainable Energy Technologies SunEnergy String Inverter - currently manufactured in Alberta, Canada. They are currently setting up a manufacturing plant in Ontario.