Eclipse Performance Test

by Allan Gonzaga

A total eclipse provides a proof point for power electronics (image Wikipedia)

In a case of the real world mimicking a test lab, the sun and moon collaborated to show just how well Gridco Systems In-line Power Regulators™ (IPRs) maintain voltage in neighborhoods with significant levels of rooftop solar PV power generation. Some of our devices are installed at distribution transformers that happen to be located near the solar eclipse path of totality as it passed over the US on August 21, 2017. And of those, some help resolve high-voltage concerns that can be caused when PV generation is high and the local load is low, such as in the middle of the day when people are often away from their homes. This is exactly when the eclipse passed through the Northern Rocky Mountains.

When power flows from rooftop solar all the way back through the neighborhood service transformer, this creates a voltage rise at customer meters. The amount of rise at each customer meter depends on their location on the secondary circuit and whether they are exporting or consuming power themselves. In the worst case, voltage rise may cause the PV inverter to “trip off,” meaning it stops producing electricity, or could possibly damage electronic equipment in individual homes.

Customer voltages depend on characteristics of the conductors, power flow direction and magnitude. IPRs provide a constant voltage that delivers reliably “Perfect Power” to the neighborhood, even when a solar eclipse disrupts solar PV production.

IPRs utilize fast-acting power electronics, rather than a traditional magnetic core, to buck (lower)/boost (raise) voltage continuously by up to 10% on the low-voltage side of distribution service transformers in overhead or underground networks. This means

IPRs have both the speed and dynamic range to ensure stable voltage to a neighborhood, even during a total eclipse.

Following the eclipse, we looked at data from two of our devices. The first is located at a site that experienced 95% of totality and the second at a site with 81%. Data showed that the IPR maintained its steady setpoint voltage, 240 V for the first site (see screenshot captured remotely via our GMAP software) and 238 V for the second, throughout the eclipse.

IPR voltage (green line) stays flat while PV power flow (blue line) through the IPR goes to zero during eclipse.
The short story is that solar output can go from 100% to 0% in seconds, completely changing the flow of power through the IPR with absolutely no change to the voltage delivered.

The power electronics-based IPR represents a departure from traditional approaches to voltage regulation with benefits of speed, dynamic range, precision and fail-safe operation that truly put it in a different class of equipment as compared to electro-mechanical predecessors. Utilities are increasingly relying on this new technology to help resolve localized voltage issues that arise as customers adopt more and more distributed energy resources (DER) over time.

Although eclipses occur infrequently, passing clouds happen on a daily basis and have similar impacts on PV production. IPRs have proven to be an effective solution in stabilizing secondary voltage as solar output shifts throughout the day due to normal variations in cloud cover or even, in this most extreme case, because of a total solar eclipse. We can’t count on Mother Nature to help us demonstrate all the advantages of IPRs, but we certainly thank the sun and the moon for their help.

You don’t need to wait until the next eclipse, or even for the next “blue moon,” to start converting problem voltage situations into IPR-stabilized “Perfect Power” neighborhoods.

Visit to learn more about how Gridco Systems products can help provide flexibility for DER hosting, get the maximum benefit from your VVO/CVR programs, or improve overall voltage and power quality for your customers.