Jan 13, 2014 03:12 pm
small off-grid: solar charge controller + inverter compatibility for LVD purpos?
Our non-profit helps train about, and install, renewable energy systems in remote villages in developing countries.
Some years ago, I started a topic on this forum, lamenting the fact that small (100-400W) inverters were not compatible with solar charge controllers (e.g. Morningstar or Phocos 12V -10A). As a result, if an inverter was connected to the DC load side of a controller, it could fry it. However, LVD protection on such small inverters is often at a very low voltage (e.g. 10.5V) instead of the controller LVD of 11.7V. So if the inverter is connected directly to the battery, chances are that it will run the battery dead. Some solutions were offered at the time, involving a relay connected to the DC load output to switch off the inverter. A simpler approach, but requiring user education and discipline, would be to connect a 1W LED to the DC load, and instruct the user to swithc off the inverter when the LED is off.
However, I noticed that newer solar controllers seem to include new features, e.g. "improved lightning protection", programmable lighting functions, etc. Does anybody know if there are either controller-inverter combos, or controllers that would be compatible with inverters, in the 50Wp to 200Wp 12V system range and at reasonable price?