A lot of people are putting solar panels on their roofs these days. The industry is going like mad as solar panels get cheaper and the solar industry gets more efficient. Most people are installing grid-tied systems in which they don't actually use solar power at all; really, they're supplying roof space for panels that pump the energy into the grid where it is bought by the electric utilities. The utilities are not growing like mad, they have billions invested in their distribution and generation systems, and they are not happy about having to buy all this solar power. It can be a real problem for them, since homeowners with solar panels still need power on rainy days and during winter when there is less sun, they have to maintain the network with almost as much capacity as if the solar wasn't there. In Arizona, they're even trying to tax the sun to cover the costs.
Writing in the Washington Post, Chris Mooney describes a scenario that is possibly even more disruptive: customers who go off-grid entirely by installing their own energy storage systems. Mooney writes:
Because solar energy is inherently intermittent — you can’t get it at night, or in a storm — the ability to store energy for these times when panels aren’t collecting, it is critical to going off grid. Thus, it is the combined solar and battery two-punch that is generally theorized as being crucial to off-grid moves – and a potentially serious economic blow to the utility industry.
But as Mooney notes, there are a couple of reasons that this is not quite the same thing as getting a cellphone and cutting the land line. A cellphone user is not self-sufficient or independent. A quick look at your bill will confirm that. The off-gridder has to build an entire system — the solar panels, the batteries and the inverters. For most people who have such systems, there has to be some sacrifice, as you only have so much electricity in your batteries and you have to use it sparingly. You have to understand what you're working with. (I once decided to use a vacuum cleaner in an off-grid trailer and emptied the system before I had finished a single room, later learning that one could only use the electric vacuum when the trailer was plugged into grid power.)
The true off-gridders who don't have a choice of grid power know all this, and are miserly in their electrical consumption. They do not expect to be running clothes dryers and giant TVs but live within their electrical means. People who are used to being grid-tied usually have different expectations.
The off-gridder who can be grid-tied is also missing an opportunity. If the system is sized to provide for the homeowner's needs in winter when the sun is lower and the days are shorter, then in summer it's going to be generating far more than can be used or stored. The grid-tied homeowner can sell his power back to the utility and make a few bucks.
If you have the bucks, then you have some interesting options. I was in a Passive House this weekend that had the best of both worlds — there were 20,000 watts of solar panels on the roof that fed back into the grid, as well as a battery bank and inverters as emergency backup for when the power went out. The house was carefully wired so that necessary things, like lighting and the fridge, kept running but the rest of the electrical system was isolated and separate. A lovely, resilient system that is very, very expensive.
However a version of this system might well begin to make sense in a few years, as the batteries from electric cars start losing their ability to fully charge and find a second life in our houses. Combined with reduced demand from more energy-efficient houses and the LED revolution, along with smart meters and two-way controls, the partially off-grid house might help the utilities save money by shifting loads at peak demand times. Instead of fighting the system and cutting the cord, homeowners might sell storage as well as power to the utilities, and still have the resilient systems needed for when the grid breaks down.
The utilities might be worried about cord-cutters, but they might also see this as a big opportunity.
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