Micro or String inverter?

Microinverters (AC) Vs. string Inverters (DC). Solar panels output Direct Current (DC). As DC electricity cannot be used directly by common household appliances nor fed into the mains grid; it first needs to be converted to Alternating Current (AC). The conversion is performed by a solar inverter; also known as a grid tied inverter. Solar panels convert the sun’s energy into DC electricity, the DC electricity is channeled into a solar inverter that converts it to 230V 50Hz AC electricity. The 230V AC electricity can be used to power home appliances, surplus electricity is fed back into the main grid.

Microinverter advantages:

  • Panel level MPPT (Maximum Power Point Tracking)
  • Increase system availability – a single malfunctioning panel will not have such an impact on the entire array
  • Panel level monitoring
  • Lower DC voltage, increasing safety. No need for ~ 600 V DC cabling requiring conduits
  • Allows for increased design flexibility, modules can be oriented in different directions
  • Increased yield from sites that suffer from overshadowing, as one shadowed module doesn’t drag down a whole string
  • No need to calculate string lengths – simpler to design systems
  • Ability to use different makes/models of modules in one system, particularly when repairing or updating older systems

String inverter advantages

  • Allows for high design flexibility
  • High efficiency
  • Robust
  • Low cost
  • Well supported (if buying trusted brands)

Use the decision matrix below to help you decide which inverter technology is best for your home. Score each of the key criteria from 1 – 5. One being not important to your decision and scaling up to five being a must have criteria. Average scores above 3 will have you seriously considering Microinverters (AC) and below 3 will have you seriously considering central (DC) inverters.

  • Electrical safety
  • Maximum panel performance
  • Full system monitoring included
  • Flexible design
  • Easy to upgrade
  • Battery ready
  • Local warranty’s
  • Local technical support
  • No single point for failure
  • STD 10 year warranty

Solar Partners NZ