New analysis from Pecan Street has found that it is possible to free 12-16% of the distribution system’s current capacity without upgrades to existing utility infrastructure.
Pecan Street used data from energy use on homes with solar PV in New York and Texas to explore the grid impacts of poor residential power factor and the system benefits of power factor correction.
The analysis showed that by improving power factor of the homes in the sample, an additional current capacity of 12-16% to the distribution system could be achieved, which is a significant increase in transmission and distribution capacity.
According to Pecan Street, residential power factor, which is measured on a scale of zero to 1.0 with 1.0 being perfect, has been declining for several years. Ironically, it is in the introduction of solar PV and other energy efficiency measures like LED lighting that has contributed to the decline. Poor power factor essentially means that more power must be delivered to homes to keep the grid performing adequately. From the white paper:
Power factor is generally lowest during daylight hours in both Texas and New York. This is partly an effect of residential solar systems producing active power, but not reactive power. When residential solar systems displace some or all of the grid’s active power with their own generation, the grid still must support the same amount of reactive power as it would if there was no solar production. As the amount of active power supplied by solar systems increases, the amount supplied by the grid decreases and the reactive power supported by the grid remains constant. This causes the power factor in our measurement to decrease. However, it is important to note that the solar systems themselves do not cause the reactive power to increase. The same amount of reactive power is supplied by the utility whether the solar system is producing power or not. However, the ratio of the active power to reactive power at the grid interconnect does change when a solar system is connected to a home.
The new whitepaper Course Correction: Residential Power Factor outlines the impacts of poor residential power factor, the system benefits of power factor correction and provides potential solutions for improving residential power factor, and policy recommendations for implementing these solutions.