California has extra distributed power sources (DERs) than some other state, pressuring it to search out methods to combine them into the grid. The interconnection guidelines that inform builders of rooftop photo voltaic, behind-the-meter batteries and electrical car chargers how a lot money and time they’ll must spend to get them grid-connected — or whether or not they’re even allowed — are a giant a part of that integration puzzle. 

Final week, the California Public Utility Fee accepted revisions (PDF) to Rule 21, which units interconnection insurance policies for every part from net-metered photo voltaic to large-scale mills, that might enable DERs to play a extra energetic position on the California grid, relying on how they’re carried out.   

The modifications embrace methods for battery-backed photo voltaic techniques to include their inherent flexibility into the grid, not by being aggregated as a digital energy plant or as a non-wires various to grid upgrades, however as a precondition of their interconnection. 

That, in flip, might assist resolve rising issues for California, like grid voltage imbalances brought on by distributed photo voltaic techniques, or grids being overloaded by EV chargers or batteries — once more, not as a response to their presence on the grid, however throughout the identical course of that brings them on-line. 

“The capabilities we’re speaking about right here by way of energy management techniques, and scheduling — they tie into microgrids, and different issues utilities are grappling with,” stated Sky Stanfield, an lawyer representing the Interstate Renewable Power Council (IREC), an business group energetic in interconnection coverage. “They get us to this distributed grid that’s extra customer-driven, but additionally extra versatile.” 

Grid flexibility, constructed into grid interconnection 

That’s the large change enabled by a Rule 21 revision entitled “circumstances that enable distributed power sources to carry out whereas avoiding upgrades.” In easy phrases, it orders California’s three massive investor-owned utilities to develop processes to permit fast-track interconnection of DER initiatives that use “restricted technology profiles” to change their influence on the grid.   

Below state regulation AB 327, California’s utilities present Integration Capability Evaluation (ICA) maps on-line displaying DER internet hosting capability on particular person grid circuits. That capability can change from hour to hour or season to season, largely from the every day rise and fall of solar energy. A brand new photo voltaic system that is likely to be simply added to a circuit underneath common circumstances might nonetheless exceed its capability throughout a couple of hours, akin to on cool but sunny days when photo voltaic technology floods the grid.  

Below the previous guidelines, that DER developer would face a prolonged research that might power it to pay for grid upgrades or abandon the undertaking. However the brand new guidelines enable techniques to vow to handle their output on a set month-to-month schedule that change from hour to hour, probably by curbing photo voltaic output, or extra possible, by storing it in batteries. 

This sort of automated, data-driven manner for brand spanking new DERs to match up with grid wants is a key objective of ICA course of launched in 2014, Stanfield famous. “We wish all DERs to have the ability to do that, as we get into excessive penetration DER circumstances.” With out some methodology to fast-track interconnections, “you’re going to have big system research backlogs.” 

Utilities nonetheless must develop guidelines over the following six months that might make it tougher for DER builders, she famous.

If circuit circumstances change — for instance, if load throughout crucial hours falls as a result of massive clients closing down — utilities can order DERs to curtail in ways in which might degrade the economics of DER initiatives. Whether or not or not that occurs “will come right down to how sure it appears, or unsure it appears, as soon as utilities work out the small print.”

Standardizing solar-storage and vehicle-to-grid charging 

This scheduling functionality additionally depends on new Rule 21 rules on battery interconnection being put in place — particularly, guidelines round batteries exporting to the grid. 

Behind-the-meter solar-battery techniques face strict export restrictions, largely to keep away from paying web metering retail charges for power saved from the grid as a substitute of from rooftop photo voltaic. However as our protection of final month’s rolling blackouts famous, storage distributors say these guidelines restrict batteries’ grid worth.

On the identical time, larger-scale solar-storage techniques are restricted to 2 classes: utterly non-exporting, or these assumed to export all their energy. This bars the choice of variable export, and requires would-be export-capable initiatives to want sufficient interconnection capability to soak up their mixed photo voltaic and storage output concurrently. 

The brand new Rule 21 revisions begin to tackle these issues, by recognizing the idea of “restricted export” and setting guidelines for the way utilities can confirm that initiatives are sticking to these limits, Stanfield stated. 

These extremely technical distinctions matter loads, since they bar interconnection till they’re resolved. For instance, Rule 21 already requires all new DERs to use good inverters with grid-support capabilities, making them the logical level to handle battery export. 

However the requirements for testing whether or not good inverter export controls and schedules are working accurately — the factor wanted to make the previously-discussed versatile DER interconnections potential — are nonetheless being developed. The CPUC offers utilities 9 months after technical requirements have been developed to implement restricted technology profiles, indicating that it is going to be late 2021 or early 2022 earlier than DER builders can use them 

This sort of lag between technical functionality and regulatory reform isn’t uncommon. Most states haven’t gone practically so far as California has by way of making internet hosting capability knowledge out there, and permitting interconnections to make use of it in a streamlined trend, Stanfield famous. 

The identical incremental progress applies to the Rule 21 revisions on vehicle-to-grid (V2G) EV charging, which is widespread in pilot initiatives however nonetheless not standardized for broad interconnection.

California already has gigawatts of EV chargers, and extra gigawatts coming as a part of its push to electrify transportation. Enabling them to export EV battery capability, moderately than merely cease charging, might make them an much more precious grid useful resource.

The brand new Rule 21 revisions make clear that V2G DC charging, or bidirectional EV chargers, might be interconnected with utility permission. That’s a primary for a state utility fee, stated Jin Noh, senior coverage supervisor for the California Power Storage Alliance (CESA). 

As for V2G AC charging, or permitting automobiles to cost on to the grid, the revised Rule 21 units up a course of to check when technical requirements can be able to standardize it. “We now have a pathway for the stationary case, and potential subsequent steps for the cell case,” Noh stated. 

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