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We hear it all the time when speaking with cooperative utilities. “I wish we could see what our local solar is doing!” In 2024, distribution-connected solar capacity will surpass 50 gigawatts in the United States with nearly 8% of homes and 6% of businesses generating solar power.
If evenly dispersed, that level of adoption wouldn’t cause challenges for distribution operators – in fact the South Australian grid didn’t start seeing significant issues until ~20-25% adoption (and they recently surpassed 100% system-wide solar generation). But solar is not evenly dispersed – as individuals are 89% more likely to adopt solar if they know someone else who has done so. The result has been clustering of installed solar systems, with utilities across the country reaching or approaching feeder-level interconnection limits.
Nevertheless, very few distribution utilities can see what local solar systems are generating on a historical, real-time, or forecasted basis. Why? At small scale adoption of solar, they haven’t needed it. But that’s changing.
In interviews and discussions with hundreds of co-ops, we’ve seen five challenges pop up repeatedly.
Far and away the most common concern of distribution operators is the risk of “backfeeding” across utility equipment that isn’t designed to handle reverse power flow, resulting in costly damage. This occurs when cumulative distributed generation exceeds local load at any point in the grid – such as on temperate spring or fall days where no cooling or heating is needed yet there is significant solar generation. If a utility has no way to monitor or forecast local solar generation, it is very difficult to even detect backfeeding let alone anticipate it.
Concerns about backfeed at substations or distribution transformers are among the most common reasons for utilities to begin to deny interconnection requests in regions with lots of existing solar. For these utilities, options like flexible interconnection can provide a path forward to allowing interconnection while protecting equipment but visibility at each level in the grid is a prerequisite.
Local solar systems are installed by a wide variety of contractors and installers with varying degrees of experience. While many are quite effective, it’s not uncommon for solar systems (and the batteries that frequently accompany them) to be installed incorrectly. Often this leads to an upset member – who calls their co-op to figure out why their bills are so high compared to what the installer promised.
Installation concerns can also create much more serious safety issues for utility staff, including unexpected backfeed during maintenance. Proactively identifying where solar and/or storage was installed incorrectly can help utilities keep community members and employees safe and happy.
Increasing penetration of solar on utility circuits can significantly complicate restoration workflows following an outage, whether planned or unplanned. Specifically, most smart inverters installed today are grid-tied – meaning that after an outage they look for stable grid conditions before permitting the solar system to generate. This typically occurs over a 5-minute interval.
A grid operator may use cumulative meter data or SCADA data (from the feeder head) to estimate how much load they will need to serve during restoration. However, with significant local solar generation, the “gross” load may be much higher than the “net” load provided by meter data or SCADA. When restoration occurs, those solar systems are not generating – resulting in gross loads that are much higher than expected, until the inverters click on five minutes later. By estimating local solar production, the utility can more accurately estimate the gross load and prepare restoration workflows appropriately.
While not a severe problem, inaccurate interconnection data is commonplace. 1kW systems instead of 10 kW. 100kW instead of 10kW. It happens all the time. On the margin, it may not matter much, but cumulative errors can result in inaccurate interconnection studies and frustration for members. By viewing estimated solar generation as compared to loading data from AMI, these errors are much easier to spot.
Finally, for many co-ops, decarbonization and renewable goals are important to their members and boards. Reporting emissions information back to these groups can be a painful and highly-manual process, typically completed once per year when updating annual reports. With continuous visibility into solar generation, this data can be freely shared in an easy and accurate way.
Co-ops that wish to gain visibility typically pursue one or both of the following methods:
Method 1: Production meters can be installed alongside solar systems to provide high-fidelity solar generation data
Method 2: Backcasts, nowcasts & forecasts for site-level solar generation can be generated using local weather data and compared to meter data
At Camus, we support both approaches: surfacing best available production meter data with 48-hour ahead forecasts and providing hourly backcasts, nowcasts, and forecasts for non-production metered solar generation.
Many of our co-op customers rely on a mix of data sources, including production meters at larger community-scale arrays and no data from residential systems. At these utilities, we use an AI-powered nowcasting toolset (developed from research at Pacific Northwest National Laboratory) to accurately estimate solar generation for sites without production meters, using data from nearby production meters, interconnection records, and NOAA weather datasets.
We then apply hyperscale computing best practices to efficiently generate meter-level forecasts for net and gross energy consumption, providing utilities with enhanced awareness of solar’s impact on local loads.
As we look to the future, there’s great potential for utilities to incorporate telemetry directly from smart inverter OEMs to provide production meter-quality data without the need to install additional hardware. We’re pursuing efforts with co-ops to explore the efficacy and cost effectiveness of this approach.
We encourage co-ops with increasing solar adoption to explore options for gaining visibility into local solar impacts on their grid. Even small efforts, in terms of time and dollars invested, can yield big gains in awareness. If you have questions or would like to learn more, contact us.
For utilities interested in learning more about this topic, check out our deeper dive into “4 ways utilities can tackle distributed solar challenges”.
