Some headway was made Tuesday in settling long-running disputes between solar developers and Xcel Energy, a quarrel that has helped delay the rollout of one of the nation’s most ambitious solar garden projects.

Between regulators’ decisions made Tuesday and a recent Xcel policy change, a critical technical issue that has threatened the viability of some solar gardens appears to be partly resolved. “There’s been incremental progress,” said David Amster-Olszewski, CEO of SunShare Energy, one of the largest solar garden developers in Minnesota.

Community solar gardens are developed and operated by independent companies like Denver-based SunShare, which must connect into Xcel Energy’s grid. A solar garden’s customers are thus able to get solar power without the expense of building and operating their own rooftop systems.

Xcel was inundated with about 1,000 solar garden applications starting in late 2014 — causing delays. Numerous disputes between developers and Xcel have caused more delays, and so far only four small solar gardens are actually up and running. Those four together generate less than 1 megawatt — or a million watts — of power.

Projects totaling several hundred megawatts — at no more than 5 megawatts per site — are waiting to be built.

Xcel said in early July that it was “more than realistic” that 200 megawatts of solar garden power would be online by 2016’s end. But with September more than half over, “there’s no way that’s going to happen,” Amster-Olszewski said Tuesday.

In August 2015, the Minnesota Public Utilities Commission, which has limited staff, created a process to hire independent engineers to review complaints from solar garden developers. The first independent engineer’s report came out in April, blasting Xcel’s cost estimates and engineering standards for SunShare’s proposed solar garden near Becker, Minn.

Since then, about a dozen more independent engineers’ reports have been filed for other projects. Tuesday marked the first time the PUC directly took up some of the reports.

Commissioners waded into the highly technical subject of “flicker,” voltage fluctuation that could cause lights in homes near a power generation source — like a solar garden — to suddenly flicker. At least 28 solar garden projects are affected by potential flicker problems.

SunShare and other solar developers have argued that Xcel’s original flicker standard is too conservative and based on archaic engineering standards. Independent engineers have agreed.

However, Xcel recently loosened its flicker standard for some, but not all, solar gardens, from a 1.5 voltage variation to 2 percent, a level many developers can live with. A PUC decision Tuesday will allow for the 2 percent flicker standard at the Becker site and another SunShare site, Amster-Olszewski said. Without that change, the Becker project particularly wasn’t economical to build.

To better measure flicker, solar developers have urged the PUC to adopt a recent standard from the Institute of Electrical and Electronics Engineers (IEEE). The PUC Tuesday voted unanimously that Xcel and solar developers together assess using that IEEE standard.

“That is a really important step forward,” said Lynn Hinkle, policy director for the Minnesota Solar Energy Industry Association, a trade group.

The PUC weighed in on another important issue brought up in the independent engineers’ reports: cost estimates.

The engineers criticized Xcel for wide variations on cost estimates quoted to solar developers for grid interconnection. Xcel argued that the company’s cost estimation process was beyond the regulatory purview of the independent engineers.

The PUC didn’t set limits on Xcel’s cost variations, as the engineers had concluded should be done. Instead, the commission voted to better monitor the variations in Xcel’s cost estimates.