A Solar Boom So Successful, It’s Been Halted


Scientific American has the story A Solar Boom So Successful, It’s Been Halted.

Photovoltaics proved so successful in Hawaii that the local utility, HECO, has instituted policies to block further expansion
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Hawaiian Electric Co., or HECO, in September told solar contractors on Oahu that the island’s solar boom is creating problems. On many circuits, the utility said, there’s so much solar energy that it poses a threat to the system and a safety issue. Studies are needed on whether grid upgrades are necessary. If they are, residents adding solar must foot the bill. And starting immediately, contractors and residents would need permission to connect most small rooftop systems to the grid.

Are we engineers at fault here?  Things that are great ideas in small quantities become problems when everybody (or even a significant fraction or people) do it.  Aren’t engineers supposed to thing about those things in advance?  Or maybe the solar installers thought, “All we need is electricians.  We don’t need no stinkin engineers.”  Although, even an electrician regularly makes capacity calculations on household circuits.  Doing so for the power grid shouldn’t have been outside their capabilities.

When you install a backup generator in your house, you also install a switch to disconnect you from the grid when the generator kicks in.  This prevents you from putting power onto the electrical grid when the utility workers think the power is out and the wires are dead.  In the case of the solar panels, they are meant to put energy onto the grid when the grid already has power on it.  So how, would they detect the situation that the grid has gone dead and they ought not put power on it?  All the solar panels connected to the grid would have to recognize the power outage simultaneously, or the presence of power from one solar installation would fool the other installations into thinking the grid had power.

In the Army, I worked on a similar issue with periscope “windshield” wipers on a tank.  There were two or three separate wiper motors.  When you turn the switch off, there is a park circuit and switch for each motor that feeds power to the motor until the wiper is sitting in the park position.  When all three motors did not park simultaneously, one unparked motor would feed power to the other motor that was already parked, and unpark it.  You can see that it would be very unlikely that you could ever turn the wipers off once you had turned them on.

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