In April, orders for home solar panels surged in California as rules for compensating homeowners for excess solar energy were dramatically changed. (I ordered the panels before the deadline to take advantage of the old rules.) Under the new rules, most customers will find their solar panels much less profitable, and it will take them longer to save money than just electricity. One way to solve the problem is to have a home battery, and an electric car is also a type of home battery. But could you help your neighbor recharge his electric car and profit if the logistics were simple?
The math behind solar power and grid power is complicated. It was easier with the old rules. During the day, your solar panels typically produce more electricity than you use, and you feed it into the grid for others to use. When the sun stops shining, you get electricity from the grid. The old net billing system simply subtracted the amount you spent from the amount you took in (with frequencies based on the time you spent). If you spent as much as you earned, then your "net" was zero, and you paid almost zero for electricity. The Grid was the perfect, almost free battery to put your extra power in and take it out later.
That's great and makes the decision to go solar easier, but utilities argued it wasn't fair, and the California PUC agreed. In his world, the value of power is constantly changing. Under the old rules, electricity could be supplied in the afternoon when there was a large surplus and the price was low, and withdrawn later when the price in the markets was higher. So under their new rules, when you use power, they pay you the same wholesale price as everyone else, and you buy the extra power you need at a higher retail price. These rates are very different in part because most of the cost of electricity in California is the supply rate, which the grid operator pays for the lines, rather than the generation rate, where you pay a distant power plant. If the power plant is on your roof and you use its electricity, there are no delivery charges, making it a good deal to go solar.
The new rules may be fairer for the public service, but they will hinder the installation of solar panels, which we do not want in the public interest. Energy providers fear that at some point in the middle of the day, households will generate so much solar power that they can't manage it. As early as 6:00pm, it's a mini-crisis when all the solar panels shut down and other power plants, mostly fossil-fired, suddenly have to ramp up quickly to cover the usual peak demand on a hot day.
At 11 o'clock, the wholesale cost of replacing solar panels is likely to drop significantly due to high solar power. The only trade-off is that the speed can be very high for short periods when the sun goes down, but that's because the sun is getting weaker and so most panels don't give much. Some estimates already suggest that solar panels will take up to three times longer to "pay for themselves," meaning a reduction in grid electricity bills in proportion to their cost, compared to old regulations. However, there is a benefit to that point, so it's still worth the investment. We may see more solar panels to the west or southwest to capture sunset light in the future. This reduces their total output, but can increase the cost of the energy they produce.
A homeowner can overcome this problem with a battery. They can store excess solar energy in a battery and later withdraw it from the grid by putting a voltage on the grid. However, batteries are expensive and wear out over time. The grid is willing to pay a premium for battery power when the sun goes down, so it can be profitable; for those who want to use their car batteries as "V2G" style home batteries, this is the only time of day at most. it's a logical time to do this, even though many cars are still on the road at night.
Car charging during the day
An electric car has a very large battery, and if you don't go on long trips, it doesn't matter when you charge it during the day. Most people charge at night because the car is parked, they sleep, and electricity is cheap at night. This is an obvious choice, except that there is no solar power at night.
For those who have a car that doesn't need to move and is plugged in at home, the best thing to do is to charge it with excess solar energy. There are a number of small companies that use data from your solar panels to tell the car to only charge with that energy, and soon Tesla cars will use Tesla solar panels for this purpose. In addition, several utilities are working with customers to shift car charging times when the utility has excess solar power, although incentives are currently weak.
In most cases, the driver doesn't care, but if you're planning a morning trip, you don't want your car to go without charging overnight as it waits for cheaper solar power during the day. The biggest burden is just remembering to occasionally tell the system to charge the car at night. Because off-peak electricity is cheap, there isn't much incentive for it, which probably needs to change. So far, the "my car is full every morning" approach is simple and attractive, but more fossil fuel based.
Commuter vehicles must be secured in office and commuter parking lots. It works even better if these properties have solar panels. New laws in France require new parking lots to be equipped with solar panels.
Local part
Some of these problems could be solved if there was an easy way to sell my excess solar power to my neighbor, especially to charge his car. As for feeding the neighbor, almost no network transmission equipment is used; in fact my immediate neighbors are directly connected to me on the same transformer. Today, under the new metering regulations, a solar owner can be offered just pennies/kWh under the new "avoided cost" rule, where only the wholesale price is paid. But my neighbor pays the full sale price and will gladly pay me something between the sale price and the avoided value, and the utility company gets a small cut since almost none of their equipment is affected.
It's not possible today, nor would it be easy if I had to set up complicated bills with my neighbors, but virtual independent energy providers can do it, certainly at a discount. The beauty of solar panels is that you can easily control their output. This allows you to ensure that you never inject more power into the network than is required by neighbors or the larger network, and never overload the devices. Some days your neighbors may take all your surplus and pay you handsomely. On other days, you may have to sell it to the network at a low cost to avoid costs. Maybe the saved costs will drop to zero in the future and you will stop sending electricity or consider getting a home battery.
As more and more people install solar, the harder it becomes to sell it to your neighbors. Therefore, not all customers will be treated equally, which may annoy some. Business parking lots surrounded by solar-powered residential buildings may be exempt from this surcharge, or vice versa. As long as the network has the capacity to carry the surplus, it would be, and if it were cheap, it would be modernized. Energy storage companies are happy to buy any surplus they can secure at a good price.
If a vehicle owner wants to implement vehicle-to-network integration, he needs to determine the right time to do so. To use the excess solar power, you must plug in the battery between 09:00 and 14:00. They should then be connected to a dedicated two-way V2G connection during peak load times (just before sunset at 20:00) when electricity rates are highest and justify the extra wear and tear on the car battery. If the two-way outlet is at home, they can use it between 3:00 PM and 9:00 PM to offset their self-consumption during peak hours, which in California can be more than 50 cents/kWh. What's important for V2G is the difference in the price of electricity going into the battery (ideally excess cheap solar power from your own panels) and avoiding cost when selling the electricity. On hot summer evenings, these costs can be quite high.
If this all sounds complicated, it is. The market opportunity is for companies and systems that make things easier and offer consumers lower costs without having to think twice, while being more environmentally friendly. To that end, PUCs should support these companies and require established monopoly power companies to cooperate with them on a fair basis for all. Electric cars need to expand the grid (but not more than in the past to meet other new needs), but this time it's important to expand it with solar energy, and electric car charging is an ideal application of solar energy when we do; easier to do things and help people save money.
