Can You Have Too Much Solar? – Part 1

Recently, I’ve seen several articles regarding problems with having too much distributed power generation (e.g., primarily home solar panels, but also small wind) on a utility grid. The best example is the Hawaiian Electric Company (HECO) restricting installation of new solar panels in residential areas. Most of the article headlines were dramatically portraying HECO as the evil utility needing strict oversight. (The bald-headed villain, sitting in a high-backed chair, stroking a white Persian cat, is merely implied.) Green Tech Media has a much more balanced overview of the situation including the technical challenges, which I’ll summarize here.

Hawaii Maximum Daily LoadHECO is limiting (or at least delaying) new solar installations in neighborhoods where the daytime power generation exceeds the consumption. (Dark blue areas in map.) I emphasize daytime generation and consumption because this is where the conflict arises. Total electricity use peaks during the middle of the day when all the stores, offices, and factories are up and running. Solar generation peaks at the same time in the bright, mid-day sun. But, electricity use in residential areas drops as all the busy little worker bees are at those stores, offices, and factories. So, just a few solar panels will meet the daytime needs of a given neighborhood. If a couple of your neighbors beat you to the punch, you’re out of luck and probably peeved.

So, back to the question, Can you have too much solar? Yes and no (my favorite answer). The traditional grid system is hierarchical and unidirectional – from big power plant to distribution system to end-user. It is not built to handle flows in many different directions at different times of the day. So in the short-term, yes, too much solar could lead to problems.

Conversely, Hawaii is uniquely positioned to operate a renewable-energy smart grid due to high electricity costs (from burning imported oil), readily available renewable resources (ample sunlight, steady trade winds, and even geothermal on the Big Island), and relatively small size. In the long run, therefore, Hawaii can accommodate much more distributed generation. Until, that is, they generate more than they can use. But, let’s cross that bridge when we get there.

In summary, I agree with HECO in regulating the amount and size of new solar power to protect the overall system (regardless of any white-cat ownership). That doesn’t mean that I think the status quo is acceptable, but it does take time (and money) to transition to a better arrangement. In Part 2, I will cover the institutional and financial issues to get from the short term to the long term.


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