Kevin Bullis

A View from Kevin Bullis

For Cheaper Solar, Fix the Inverters

One component of solar panel arrays can cut power output by 40 percent, driving up the cost of solar electricity.

  • June 5, 2009

If solar power is ever going to be a major source of electricity, researchers, engineers, installers, and solar panel array owners are going to have to pay closer attention to one essential component of the these systems–the inverter.

According to a study of solar arrays in actual operation, poorly designed or faulty inverters–devices that convert the DC power produced by solar panels to AC power that can be used in buildings or sent over the grid–can dramatically lower net power output. In one case, the inverters consumed hundreds of watts at night, decreasing overall power output by 40 percent. High temperatures caused inverter faults, and because the inverters had to be reset manually, about half the time when the sun was shining the array was producing no power.

What’s more, the common practice of linking all the solar panels in an array to one inverter means that if there is a problem with one panel in the array, the output of the whole system goes down. So, because of inverter-related problems, solar arrays might produce nowhere near what they’re supposed to, and solar power may prove even more expensive than expected.

One option is to install automatic disconnect circuits, which can cut down on parasitic losses. Presumably inverters that reset automatically after temperature faults–or that can operate better in high temperatures–would also help. Several companies are also starting to develop micro inverters or other electronics that can be installed at each solar panel so that if one panel has problems, the rest aren’t affected.

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