I participated in a panel discussion on net-metering the other day at Colby Sawyer. The panel consisted of Richard Lebreque from Eversource Utilities, Representative Lee Oxenham from Plainfield, and me (solar installer).
Net-metering is what allows home-owners to “sell” extra solar energy to the grid (usually as credits) and then get it back at night or even through the winter if enough is saved from the summer. (See Net-Metering: Past Present and Future for background)
In New England net-metering is especially important since we have so much more sun in the summer than the winter. The Utility company basically acts as a very big battery bank holding onto our extra production for a future use.
This year many of the NH Utilities have met their “solar cap” (it is a slightly different number for each utility), and they are not required to allow any more solar arrays to connect into the grid.
Without this capability, most homeowners and business owners would find it difficult to justify the finances of installing solar.
During the panel discussion, Richard explained how the distribution wires, sub stations, and transformers that make up the “grid” are designed to meet the highest peak demand of all the businesses and homes that are attached to any section or “circuit” of the grid.
The utility companies have to anticipate how much energy we are all going to use over the next few decades if they hope to serve customers and keep the lights on…which they do really well if you think about the number of new electronic equipment and devices that can be found in the average home compared to 20 years ago. It’s actually pretty amazing that the grid has held up as long and as well as it has.
From this discussion what hit me is the idea that Utilities had to design for the peak demand. And that peak continues to go up higher and higher every year as we seem to have a voracious appetite for the latest technology. It is true that many people are aware of energy use and will choose “energy star” appliances and will change out their light bulbs to higher efficiency ones…but the total consumption of electricity continues to climb.
So what is the “peak demand” that the grid needs to meet, and are there other ways to address the problem of too high a demand?
Think about your own home and what times of day and times of year do you use the most electricity. If you heat your house with electricity (even if you just use electrical space heaters), then your peak demand will be at night in the winter. If you use air conditioning, then your peak demand will be in the summer, during the day. If you heat hot water with electricity, then your peak is probably the morning or evening when people take showers or do the cleaning.
What about the commercial business down the street that employs 10 people and does auto repair? Their peak power demand is probably between 9am and 5pm and may vary dramatically depending on what equipment they are running any given day. Their peak demand may change seasonally.
It really is a good engineering problem for a utility company to figure out how meet all these different demands. Today, they turn on/off propane, oil or coal generating machines to meet the loads as they vary through out the day.
If a significant contribution to a utility’s energy generation is solar… it can’t be turned on or off at will to meet a peak demand. They can’t even depend on it providing some percentage of the base (unchanging) load because we may have a cloudy or stormy day. There is a similar problem with wind in that we can’t depend on a constant wind at any particular time of the day or season.
So, to address this peak demand we have to develop some more tools and strategies which might include:
- Education for home and business owners so they can know and plan when to use the higher demand equipment. If you own solar panels, maybe you can plan the use of washing machines, dehumidifiers and business equipment to coincide with a good sunny day.
- “Smart” controllers connected to all our large energy use equipment, so the utility company can turn off some air conditioners or heaters for an hour during a peak period that would otherwise require them to start up another coal or oil plant.
- Add storage to our renewable energy systems, probably in the form of batteries. There are lots of new battery technologies being developed right now that can be added to solar generation systems to provide the energy needed during peak demand times, reducing the demand on the grid.
- Conservation is really the most important thing we can all do to help reduce peak demand on the grid. When you buy a new piece of equipment (for your home or business) think about how much energy it takes and when and how often you need to run it.
- Some people will choose to go off-grid, requiring their own storage at their home or business, and requiring them to be very conservative with all their electrical needs.
Understanding a little about the design challenge facing the utilities helps to put things in perspective.
That said, I believe NH’s solar cap is the lowest in New England and the end to net-metering has put a halt to what was a strong advancement of solar in NH. We really need to raise the cap in our next legislative session (starting in January), while figuring out the right long term solution(s).