Power companies whine a lot about the “problems” that solar power causes for grid management. That is one of the reasons power companies want to impose penalties on solar generators.
One of the “problems” that power companies whine about is the fact that solar generation on the grid peaks (in the middle of the day) just before major demand peaks between 5 and 8 in the evening. Here is a chart of California’s system presented in this article in Renewable Energy World about the whiners:
This graph is known as the duck chart, for obvious reasons. Note that the only actual data is shown for the lines labelled 2012 and 2013, although the 2014 projection is probably pretty close.
Here’s the whine:
The duck is the perfect vehicle for utility complaints because it casts the growth of distributed solar as a major technical problem (an area where most policy makers defer to utilities) rather than an economic one, where utility complaints can be contrasted with their customer’s desires for more local control over their energy use and costs.
The utility companies crying “fowl” highlight a particular part of the duck chart: the dramatic ramp up in power generation on the light-green 2020 curve that happens in the late afternoon, as energy produced from solar wanes but energy demand rises. In the traditional grid operating model, accommodating this ramp-up in energy use requires a lot of standby power from expensive to operate, rapid-response power plants.
Whiners whine, but are they right? No.
Evidence suggests utilities are crying “wolf,” with several experts poking large holes in the utility argument. The Clean Coalition and Regulatory Assistance Project have both offered numerous strategies utilities can use to “flatten the duck” or “teach it to fly:”
- Target energy efficiency measures for the “ramp up” period
- Orient solar panels to the west to catch more late evening sun
- Substitute some solar thermal with storage for solar PV [I’d suggest adding storage to PV also works]
- Allow the grid operator more demand management via electric water heating [already done extensively by rural cooperatives in Minnesota]
- Require large new air conditioners to have two hours of thermal storage accessible to the utility
- Retire inflexible generating plants (read: coal and nuclear) that need to run constantly in off-peak periods
- Concentrate utility demand charges on the ramp up period.
- Deploy electricity storage into targeted areas, including electric vehicle-to-grid
- Implement aggressive demand response programs (subscribing more businesses and homes into programs to shed their energy demand at key periods)
- Use inter-regional power transactions
- Selectively curtail a small portion of solar power generation
In other words, the technical challenges of the duck are manageable, largely with existing technology.
The economic problems for utilities — stemming from an outdated business model — may not be so manageable.
So the problem isn’t with solar power generation. The problem is that big base load generators are clinging to their obsolete investments and want the rest of us to pay for it.