Sunday, March 08, 2015


PV panel technology that even HECO may welcome and ratepayers should demand

Rooftop solar power systems are picking up a second job on the distribution grids that deliver electricity to California homes and businesses. Right now, their photovoltaic panels just generate electricity (meeting about 1 percent of the state’s consumption), but within a few months some systems will also start moonlighting as junior grid regulators—a role that could keep them busy even after the sun goes down.—IEEE Spectrum February 2015

by Larry Geller

Anyone who follows the news—and especially readers of Henry Curtis’ blog—knows that the Hawaiian Electric Company has blocked new installations of rooftop solar panels, leaving 2,000+ homeowners anxiously awaiting approval and stifling Hawaii’s solar installation business.

The issue, in a nutshell, appears to be that HECO says its grid can’t handle all that solar power injected into it and remain stable.

Well, there appears to be a technological solution adopted in California, Germany, Japan and some other countries that turns the tables on the grid operators.

An overvoltage scare

Power line voltage errors are no joke. One day my computer’s UPS started beeping: “overvoltage! overvoltage.” I was protected, but as the voltage kept creeping up, I wondered if there would be damage caused. I unplugged the TV and some other things as the voltage passed 130 volts and got hold of the condo management.

They didn’t believe me at first. Surely my voltmeter must be defective, this never happens.

By the time they verified the over voltage, it was 147 volts at my wall socket. I suggested that if the voltage increased much more, the elevator electronics in each building could be fried. Residents would lose their TV sets or other appliances if they were in use. Indeed, just then, all the elevator buttons lit up and they stopped running.

The manager called HECO and the problem was corrected. No elevators were harmed in the end. Whew!

This was an extreme and unusual case, but it illustrated the problem of voltage variations on the power grid.

Without getting too geeky about it, utilities spend money on equipment to stabilize voltage and frequency on the grid already. That equipment is located at generating plants and substations, and makes sure that all of your clocks, appliances, computers and all the industrial equipment drawing power from the grid can be operated safely and efficiently. If PV power disrupts the grid, other users would suffer.

Hawaii’s technological backwardness should not stop us from copycatting what California is doing. Their standards would assure that PV installations, in the long term, could continue, and actually could save the utility some money as well.

Here’s the scene, as HECO and other utilities see it:

At times of low power demand, high solar output drove up voltage levels, explains Bernhard Ernst, grid integration director for inverter manufacturer SMA Solar Technology, based in Niestetal, Germany. Such situations prompted utilities to freeze PV installations on certain lines.

[IEEE Spectrum, How Rooftop Solar Can Stabilize the Grid, 2/21/2015]

Germany adopted new standards three years ago, according to the article, which California built on to develop its own standards. Under these standards, PV owners turn into grid regulators, both under normal day-to-day operating conditions and in emergencies.

California’s standard, developed through a collaborative process that began in 2013, pushes the envelope for smart inverters. Though solar causes few problems for California utilities today, rooftop PV is growing fast—by more than 40 percent per year in San Diego Gas & Electric’s territory. The state’s smart-inverter standard starts with Germany’s requirements and then asks inverters to be smarter still.

Adopting (that is, copying) the California standards is something our Public Utilities Commission could do. It would also have the effect of staving off objections that either HECO or NextEra (should the proposed acquisition go through) have to adding privately owned PV systems to the grid.

Of course, this will take some study. The question of whether these new standards should be adopted needs to be handled independently, since ramping up rooftop solar may not be something either HECO or NextEra particularly fancy.

But is it reasonable that we should continue to pay three times the national average for electrical power? The need to reduce everyone’s cost of living should be a priority for the PUC. We’ve been quiet too long on this subject.

If this technology will allow PV installations to be unleashed, and cheaper power to appear on the grid for everyone, let’s go for it.


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