How to Grow it Here (Part 2)
Author: Ralph Jacobson
What Do We Mean By The 4th Market Bucket?
Let’s look at this through the lens of tariffs offered by the utility for distinct segments of the solar market, affectionately called “buckets.” A tariff is a standard contract, approved by the utility’s regulators, which defines the transaction between the utility and its customers who own solar. The net-metering tariff is offered to residential, commercial, and industrial customers for PV systems up to 1,000 kilowatts. This first bucket for solar has been the foundation for the solar industry for decades.
The second bucket is the community solar garden, which uses a tariff based on the “value of solar” concept to price the bill credit given to subscribers. Utility-scale solar, a third bucket, is just entering the market in Minnesota as the price of solar continues to come down. Being larger and relatively few in number, these transactions involve power purchase agreements (PPAs) and other purchase contracts where price and longevity are the key drivers.
Creating The 4th Market Bucket: Dispersed Solar
Dispersed solar arrays, DG for short and sized from one to ten megawatts, may be too large to be supported by policy-driven incentives, and too small to be competitive by a wholly economics-driven analysis. But recognizing that DG solar can utilize smaller parcels of land closer to loads, be quicker to deploy, AND be more compatible with utility business models, DG solar models will actually gain more traction in the solar marketplace than the CSG model.
To facilitate DG solar, we would do well to identify what need there is in the clean power market for solar arrays at mid-scale, how this market differs from what we already know, and what is needed to make it work for both utilities and solar developers. This will be a planning-driven market, and this should be seen as the goal of the distribution planning process initiated recently under the auspice of the Minnesota Public Utility Commission.
Why Consider Dispersed Solar?
A recent article, “Is Bigger Best in Renewable Energy,” by Maria McCoy of the Institute for Local Self-Reliance, makes the case that there are limits to the economics of ever-bigger power plants. Very large solar arrays will likely require investment in new transmission lines, adding significant cost and longer timelines to utility-scale arrays. Other factors such as the cost of other infrastructure, powerline losses over longer distances, uncertainty in the market, and public attitudes about the use of agricultural land will take a great deal of political capital to overcome. In comparison, DG solar can be quicker and easier to plan and implement, as will be discussed further along.
Another advantage of DG solar is that more widespread dispersal of solar arrays will tend to minimize the edge effects of clouds. The leading edge of a cloud bank can cause a sharp drop in power production, while a sharp increase in production can occur as the sun comes out from behind the trailing cloud edge. While electronics can minimize the edge effects of clouds by smoothing the ramping up or down of production, the fact remains that the more compact our solar is (i.e., fewer but larger arrays), there will be more impact from edge effects to be dealt with.
How Will Dispersed Solar Fit Into The Power Grid?
Utility-scale solar arrays are located on the transmission side of the power grid, more like central-station power plants. Dispersed solar arrays can be located on the distribution-side, much nearer to the farms, factories, and cities where the energy will be used. It may be more accurate to describe them by function or location in the electric system, such as feeder line support, than it is to describe by other categories.
A legitimate question to ask is, if community solar gardens are really taking off and very popular with electric customers of Xcel Energy, why can’t the model just be scaled up to take its place alongside utility-scale solar to realize the full potential for clean power? And furthermore, since it costs a little more per kilowatt-hour to build a dispersed solar array than it does to build a utility-scale solar array, what are the benefits which justify the extra cost and work of creating this 4th bucket for DG? So, let’s examine the market potential for community solar.
Next Time: How Much Can The CSG Model Be Scaled Up?