Traditionally, the reliability of small PV systems’ power output has been a concern for utilities, project developers and grid operators, since all it takes is a few clouds to disrupt the power flow of a small array. But the Berkeley Lab study suggests that when PV plant arrays are spread out over a geographic area, the variability in power output is largely eliminated.
This means that for utilities, the distributed generation of small PV arrays could mean increased efficiency, reduced costs and a quicker path to a cleaner energy portfolio.
The boon of concentrating solar thermal power plants is their ability to deliver more consistent electricity, and to offer thermal storage (cheaper than batteries) to expand their daily coverage.
But it might be in serious trouble. And this time the culprit is not cheap natural gas, the Koch Brothers, nor the desert tortoise advocates.
…The relentless price declines of PV panels allows developers to build PV plants at a lower cost than their [concentrating solar thermal] CST cousins. This issue is illustrated in the following Capital Cost per watt chart (an excerpt from the upcoming GTM Research “CSP Report”). In 2010, the price to build a CSP park run by Troughs, Power Towers or Dish-Engines will cost between $5.00 and $6.55 per watt (AC). On the other hand, utility-scale PV projects can limbo below $3.50 a watt (DC).
Distributed solar photovoltaic (PV) proponents have recognized that solar is not without economies of scale – larger installations generally have lower installed costs per Watt of peak capacity. But new data suggests that these economies are significantly smaller than previously … Read More
Residential solar PV in Los Angeles is getting a huge boost from a new community solar buying group. With typical residential installation costs for crystalline solar PV, residents would see a 20-year payback on a solar PV installation or a … Read More
Rooftop solar is no longer the playground for granolas and Germans. But even when utilities join the solar PV game, they find that the distributed nature overcomes many of the technical and political barriers. A 2008 change in federal tax policy opened the door to utilities to invest in solar PV and utilities like PG&E are planning sizable installations (250 MW). PG&E will do a ground-mounted field of modules in the desert, but other utilities are finding distributed PV makes more sense:
Southern California Edison already plans to scatter 1 MW and 2 MW rooftop PV installations across its service territory, part of its goal to deploy 250 MW of PV over the next five years. Minimizing transient spikes is one reason. A second is that transmission remains the No. 1 barrier to renewable energy growth in California, says Mike Marelli, the utility’s director of renewable and alternative power contracts. “We can implement smaller systems with little or no transmission” additions, he says.
It’s hard to argue that transmission is a barrier when you’ve got 250 MW coming online without it! The good news is that the distributed solar also helps overcome some of the variability issues with solar power:
“During cloudy periods, the output from PV can get noisy with spikes,” which can have an effect on the grid, says Kelly Beninga, global director of renewable energy for WorleyParsons. PV installations around 20 MW in size can be managed without too much trouble. Larger than that and portions of the grid can be affected by passing clouds… To better understand the issue, NV Energy is studying power output variations that may result from deploying PV in and around Las Vegas. The study won’t be complete for another year, but Tom Fair says early data suggest that geographic dispersion helps dampen variability. A second finding is that solar facilities need to be placed on strong parts of the grid. “That leads us away from having huge amounts of PV at any one site,” Fair says. Ten to 20 MW at any one site might be the limit.
The utility interest in solar PV may help remove some of the stigma, and show that even small-scale modules can have a big-scale impact.
Photo credit: Schroeder, Dennis – NREL Staff Photographer