A Monster of a Solar Issue in Hawaii


As solar tensions flare in Hawaii, Greentech Media takes a look at what is happening there and what it means for solar in the rest of the country. With 10% grid penetration from solar on Oahu, the utility is starting to see some issues with their existing model and infrastructure.


Hawaii has become a hotbed of solar intrigue. It’s the first state to experience issues from large amounts of distributed solar coming onto the grid. That’s because solar is so popular there, given the very high electricity costs in the state, that adoption has skyrocketed. 

As we discussed recently, the issue centers around concerns that the grid in Hawaii can’t handle the increasing amounts of solar coming into it. This has come to a head now, and stakeholders are looking at what this will mean for solar on the islands.


It’s such an important issue to resolve, not just for Hawaii but for the rest of the nation, that Greentech Media ran two stories on the situation today.


For some great background on the state of solar in Hawaii and a look at what the grid there can handle, check out this article by Eric Wesoff. He explains that although studies indicate that the grid can handle 20% DG penetration, and just 10% of Oahu utility customers have gone solar (that’s something, when we can say “just 10%”), challenges are already emerging. That’s in part because because the percentage gets much higher in some neighborhoods.


The article includes a response from the utility, Hawaiian Electric Companies (HECO), to the situation, plus insights from GTM analysts.


The upshot is that there are still many unknowns. The rest of the country is watching how Hawaii will resolve their solar situation because, as Wesoff quotes as solar installer as saying, “We are all participating in a grand experiment.”


Apparently, that experiment includes monsters — of the Loch Ness variety. Move over, Duck Curve: Nessy is here! Jeff St. John at GTM reports on the situation.


The Duck Curve, of course, refers to the challenge that grid operators in California have been anticipating. In the past, demand for power would go up gradually during the day as people returned home from work. As more distributed solar comes on to the grid, demand drops during the mid-afternoon, when the sun is shining. Then, when people come home in the evening and the sun goes down, there’s a big spike in demand. When laid out in graph form, this demand curve looks like a duck — with the head representing the demand spike.


The issue is that it’s hard to ramp up traditional power plants quickly enough to meet a quick spike in demand.


In California, some effects are being seen already, but the real issues remain in the future. Hawaii, on the other hand, is dealing with them now. In fact, according to Dora Nakafuji, director of renewable energy planning for HECO, the chart in Hawaii is looking more like the Loch Ness Monster.


That’s because Hawaii already has so much distributed solar coming into its grid in some areas that its driving system-wide demand curves below zero some days. In California, distributed solar is expected to reduce demand during the day, but in Hawaii, it goes beyond that — on some sunny days, more power is coming into the grid and “backfeeding” the system. At that point, the monster curve “dips underwater.” And that’s a challenge for the grid, and for the utility. It also makes for an even bigger spike later in the day.


We’ll continue watching the developing situation in Hawaii. Let’s hope a solution proves far less elusive than Nessy.