A roadmap for making residential solar work
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- Aug 25, 2019 7:30 pm GMTAug 25, 2019 7:45 pm GMT
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This item is part of the Special Issue - 2019-09 - Distributed Energy Resources, click here for more
The current environment for residential solar is geared to early adopters and people who are willing to take a risk. The regulations have enshrined, in most states, a risk reward structure that rewards the early movers and transfers costs to the people who have not moved to install solar. Per million customers most utilities are seeing around 2,000 applications for solar a year based on 2018-9 numbers. That means at the current rate all dwellings will not have solar before 2070, well beyond the time period that most environmentalist want to see 100% renewables.
The way the regulations are written, people who can afford it want to be net-zero so they never pay a utility bill, but in a state like Michigan an average residence uses 8 megawatt hours a year with a peak usage of 2 kilowatts, and to be net-zero that same home needs to export over 5 megawatt-hours, which they then re-import and they have a peak export of over 6 kilowatts, but because of the legacy net metering tariffs, they pay nothing toward maintaining that infrastructure, that they now use more of.
Michigan has moved beyond the net-metering tariff, as have other states, but the structural regulations still reward early adopters and limit the speed of solar installation, as well as getting it installed in a fashion that actually helps the electrical system operate.
If we put aside the legacy of solar and spend some time looking at it as an engineering problem some clarity emerges.
- Most dwelling peak usage is between 1 and 3 kilowatts, to be efficient at using the resources, most of the energy should be generated where is it used with little export or re-import
- Storage is and will continue to be expensive. Between energy losses going into and out of storage, even if the actual cost comes down, the losses going into and out of storage add to the cost of the infrastructure needed. More solar panels to replace the lost energy, larger inverters, and bigger batteries.
- Making solar an “add-on” is more expensive than changing the building codes to make the wiring infrastructure needed a standard item in all new homes and major remodeling projects, similar to what was done with smoke detectors.
- Financing programs offered by solar installers are good for the solar installers, not the end customer, making solar out of reach for many customers with poor credit ratings. No one can fault the installers for wanting to make money, but if you want social justice then must be an alternate financing program.
- Placement is currently based on who wants to pay for solar when, not by what is good for energy prices, infrastructure or any external factor for the greater society.
Ignoring existing regulations, and thinking like an engineer, these 5 principles create a very different solar program (2KW is being used as a number for illustration, it will vary by state):
- Solar is part of every dwelling, each dwelling should be allocated 2 KW, if a neighbor has desire to put in 4kw, then I can sell them my 2KW allocation.
- Utilities would have responsibility to run a program that is focused on getting 2KW on every dwelling in a defined time period. The program can be internal, or third party or any other method desired, but the utility is focused on EVERYONE having solar. Utilities will look at where the solar should be installed each year, to maximize its value to society as a whole.
- Financing program is backed by the state government or the distribution utility. Either choice works, Landlords and homeowners can choose alternate financing, but for people with no good alternative, the state or the utility should be the backstop.
- Power created by the panels should net out for the location that it is installed on, but demand – in either direction is tariffed by the amount of demand, that pays for the infrastructure. If you want to have 20KW of solar on the roof, fine, but the grid is not a “battery” and if you export 19 out of 20KW, then you pay a demand charge on that 19 you export.
- As households add electric vehicles and storage, then the size of the solar installation that the backstop program will cover should increase. Again, the goal is to use most of the power within the dwelling and not export at all. If charging is only done at home at night, then either batteries are installed, or the program does not back your larger installation.
- Regular maintenance and inspection of the installations needs to be included in the program, many systems develop issues over time, and the occupant of the dwelling seldom has the experience, skills or information to recognize the need for maintenance or to actually perform said maintenance, wasting the value of the asset.
- Distributing solar in this fashion would mitigate some of the cloud transients, the spilling of solar when load is low and the impact on the distribution system.
All in all, an engineering approach to solar would add significantly to the total solar in the system. With 130 million dwelling in the US, a 2 KW program would add about 260 GW of solar over a defined time period and would be socially just, and would not work against the electrical infrastructure that is installed, but would rather, reduce peak daytime loading. This reduction would mean the same infrastructure when called upon to charge electric vehicles at night would be cool and ready to take up that charging need.
There is more, but this article is already too long.
The opinions shared in the article above are those of the author and do not necessarily reflect or coincide with those of Burns & McDonnell.