Stuart A from Boulder, CO. Xcel Energy territory. Brewery client installed a 200 kW rooftop solar array last year. Before solar, their power factor was a steady 0.91 — just above the 0.90 threshold, no penalty. After solar, their PF has been swinging between 0.82 and 1.05 depending on the time of day. During peak solar production the inverters are pushing the power factor leading (above 1.0) and during evening hours when the brewery runs heavy motor loads without solar, the PF drops to 0.82. Xcel is penalizing for both the lagging (below 0.90) and leading (above 0.95) conditions. Monthly penalty has been averaging $920. The client is furious because they invested $340,000 in solar to save money and their electric bill actually went UP because of the power factor penalties.
Solar panels pushing power factor leading — utility penalizing for it
Stuart, this is becoming a major issue as more commercial buildings add solar. The inverters inject real power but can also inject or absorb reactive power depending on their settings. Most modern inverters can be programmed to maintain a target power factor but many installers leave them at default settings which optimize for real power output without considering reactive power impact. Has the installer been contacted about reprogramming the inverters?
We are seeing this across Colorado. Xcel has a specific tariff provision for distributed generation that addresses power factor. Check Schedule RE-TOU Supplementary Section 8. It has requirements for power factor at the point of interconnection. If the solar installer did not configure the inverters to meet those requirements, the installer might have liability for the resulting penalties.
Carl, pulled that section. It says distributed generation facilities must maintain power factor between 0.90 lagging and 0.95 leading at the interconnection point. My client solar array is clearly violating both limits at different times of day. The installer should have programmed the inverters to stay within that band. Going to contact the installer.
Stuart, most commercial solar inverters — SMA, SolarEdge, Enphase commercial — have reactive power control settings that can be configured to maintain a target power factor range. The installer probably left the inverters in default unity power factor mode which means they only produce real power and do not manage reactive power at all. A good solar electrician can reprogram them in an afternoon.
Duane, thanks for the technical detail. The inverters are SMA Sunny Tripower units. Called the installer and they confirmed the inverters were left in default mode. They are sending a tech to reprogram them for power factor management within the Xcel-required 0.90-0.95 band. No charge because it should have been done during commissioning.
Inverters reprogrammed. First month with the new settings: power factor steady at 0.92, zero penalty. The $920/month penalty is eliminated. But my client still wants to recover the 10 months of penalties that accumulated since the solar was installed — about $9,200. That is where it gets complicated. Is this Xcel fault, the installer fault, or the customer fault?
The 10 months of penalties are a gray area. Xcel billed correctly per the tariff. The customer chose to install solar. But the installer failed to configure the system to meet the interconnection power factor requirements that are in the Xcel tariff. I would pursue the installer first. If they have E&O insurance, $9,200 is well within a small claims threshold. The customer could also file a complaint with the Colorado Electrical Board if the installer is licensed.
Contacted the installer with a demand letter citing the Xcel tariff PF requirements and the $9,200 in penalties resulting from their failure to configure the inverters. They offered $6,000 as a settlement to avoid a formal complaint. Client accepted. So the client recovers $6,000 of the $9,200 in past penalties, the ongoing penalty is eliminated saving $11,000/year, and the solar array is finally performing as intended.
Stuart, this case is going to become more and more common as solar adoption grows. You should consider developing a specialty in solar power factor audits. Every commercial solar installation in Xcel territory needs to be checked for inverter configuration. The installers are solar experts, not utility billing experts. There is a gap there.
Carl, already on it. I reached out to three solar installation companies in Colorado and offered to review their completed commercial projects for power factor compliance. Two of them said yes immediately. They would rather pay me to find and fix problems than deal with angry customers and demand letters. New revenue stream.