Rule 21 governs interconnections made to California’s investor owned utilities and those regulated by the California Public Utilities Commission, such as PG&E, or SCE in Southern, California and SDG&E in San Diego. Rule 21 outlines the interconnection agreement homeowners and utilities sign before a new solar system is connected with the electricity grid. It’s purpose is to outline safety features and advanced grid functions for the inverters. This short article will outline what an inveter is, what smart inverters are important and how Rule 21 will impact solar consumers in California.
What Is An Inverter?
An inverter is an integral component of a commercial or residential solar installation. Solar PV panels create an electrical current that is DC, or direct current. However, most household appliances and electrical uses require an AC, or alternating current. The inverter is vital to a solar installation as it converts the DC electrical currents a PV panel produces to an AC current that can be used by the homeowner. Without an inverter, AC electricity cannot be fed into the home.
What is Important About Smart Inverters?
Early inverters, sadly referred to as “dumb inverters,” were programmed to turn off at the first sign of any disturbances on the electrical grid. The problem is with so many homes connected to the grid through solar energy, the impact of all the home interconnected with solar is devastating. The sudden loss of generating capacity sets off a cascading effect that increases grid volatility. Thus, the solution to stabilizing a volatile grid actually made it more volatile.
Smart inverters, on the other hand, are more sophisticated versions of early inverters and can make autonomous decisions that help maintain grid stability, reliability, and power quality. Smart inverters connected to the grid can help facilitate reliable, quality power distribution throughout the energy grid.
How Will Rule 21 Change Solar?
In California, current regulations will not impact solar customers much at all. As of September 2017, the major utilities and investor owned utilities in California required all newly installed systems be paired with a smart inverter, such as one manufactured by Enphase or Solar Edge.
However, as Rule 21 continues to be modified, changes are in the pipeline.
First, after July 26, 2018 all newly installed inverters will need to be set to the Reactive Power Priority setting, which will ensure the two-way fluidity of energy being sent between the grid and a homeowners solar installation. For the inverter, software updates will be rolled out.
Phase two of the Rule 21 roll-out will set the common language for how inverters, solar energy systems, and the utility systems talk to each other. Systems must be able to communicate over the internet. This is still an area of development, and no date for rollout has been set, as there has been no decision as to who should foot the internet bill – the utility or the homeowner.
Phase three will cover additional inverter functions such as data monitoring, remote connection, and disconnect and power controls. This phase also does not have a set timeline.
What is Important for Solar Customers
First, if you already have a system installed, and it was installed in the last 18 months, you can rest assured that the inverter you have purchased with your solar installation is compliant with Rule 21, in California. These inverters already have been installed with the ability to manage the up-and-coming changes to the grid and inverter connection. Updates to software will be able to made digitally in most circumstances.
If you are still exploring options for your commercial or residential solar installation, take time to discuss Inverter options with your Energy Adviser. Seek confirmation that the inverter you are purchasing with your system is currently, and will maintain, complaint with California interconnect mandates and will be able to handle any changes in the pipeline.
If you have lingering questions, reach out to one of our Energy Advisers or stop by the showroom located in downtown Brentwood. A few minutes could clear up and misinformation and ensure your peace of mind.