Your local utility may offer rebates for the purchase of a new EV or the installation of a residential Level 2 charger

salyavin said:

Some california utilities are playing with turning off and on your charger based on power demands with you the owner having an override, this can help you save even more money than off-peak. Xcel has some of the technology but has not implemented this yet, it only works with 2 charger models I think it was. Xcel is moving everyone to time of use so peak vs off-peak matters. Mind you most of the time I make more electricity than I use.

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They refer to this as Demand-Response, and they compensate customers willing to participate.

Utility rates skyrocket when demand soars, such as hot summer afternoons. If the utility cannot generate enough power to meet demand, they buy excess power from others in an auction, which means rates can go through the roof in widespread high demand periods.

An alternative to producing more is to cut use. Many CA utilities have the ability to control Air Conditioning and Pool Pumps during high demand periods, and are adding EVSEs to their Demand-Response programs. So, by temporarily disabling the higher energy appliances, they can avoid having to buy (as much) excess power at auctions. Usually, in areas with widespread participation in DR programs, the temporary outages may go largely unnoticed due to being relatively short periods.

CO probably doesn't have as critical of a need (yet) for DR programs, but all of the utilities are preparing for it. For now, encouraging off-peak charging is likely enough to avoid critical shortages, but as populations continue growing, EV adoption accelerates, then DR may become an important piece for cost containment.

CA has seen peak demand periods shift due to rooftop solar. Whereas 1-3PM was often the start of peak rate periods (due to high air conditioning demand), the energy generated by customer's rooftop solar is now filling the gap so there is much less strain on capacity. Now, many TOU plans start peak periods after 3 or 5PM as rooftop solar capacity wanes.

Similar peak-shifts may occur due to EV charging. If a utility starts off-peak rates at 9PM for instance, and all EV owners set their charging to start at 9PM, a surge of power use will occur and potentially create a shortage. So, many will define this as mid-peak and charge a bit more, then set off-peak later in the evening. With so many rate periods to consider (these are often different by season as well), it can be confusing. DR can help by allowing the utility to manage the EVSE demand during the surge or the occasional spikes in demand that may occur throughout the off-peak period. It all sounds complicated, but automation helps keep it simple for both the utility and consumer.

The whole thing is a cat and mouse game. Coal and gas generation are frowned upon, and renewables are gaining favor. Add increased demand from EVs, and potentially more AC use due to warmer climates, and simply replacing coal and gas generation may not be enough. Sure, grid storage can help shift the renewable energy for peak period use, but there are a lot of moving variables. DR can be a critical component during uncertain periods, and in most areas, these ultra-high demand periods are short lived and only a few days per year. I suspect within 5 years, DR will be a fairly widespread strategy.

To participate in a DR strategy, an EVSE would need the capability to be remotely controlled. Alternatives include separate circuits for the higher use appliances, with smarts incorporated into the circuit breaker or sub-panel. And, some EVs have cloud services like OnStar for GM vehicles, or Tesla which may be able to control charging activity remotely. For an EVSE to participate, it generally needs the ability to speak the language of the grid, and OCPP capable EVSEs do just this. OCPP is the protocol used by public charging networks to handle billing and activation "at the pump". It requires an internet connection for OCPP, thus "Smart EVSEs" are the first step. Most of the Smart EVSEs can, or will be able to support OCPP. With OCPP, utilities can get detailed time of use data from the EVSE directly (for billing purposes), as well as limit the current supplied to the EV, or even cut it off entirely for DR programs.

OCPP itself is a moving target, with different versions and certification processes. So when utilities limit your choice as to which EVSE they will support with their TOU and DR programs, it comes down to models that are certified to work within the parameters of the programs. Generally, there is a third party cloud service that acts as a middle-man in the whole scheme, so the EVSE communicates with the cloud service, the utility reports demand to the cloud service, and the third party uses both inputs to determine if or when to take action. Similarly, the cloud service reports EVSE use data back to the utility. So, a utility could offer TOU plans for EV charging (only) and keep the rest of the home on a flat rate plan. Once a month, they would reconcile the home's total kWh use with the time of day the EVSE reported use and calculate the bill based on both.

Wow you clearly know a lot more than I do about this. What little bits I know come from a meeting I went to with the Colorado Energy Secretary and Xcel. I do know Xcel is preparing for it but yea does not have any date on offering it. Xcel does have a "saver's switch" they call it so they can turn down your air conditioner during peak and they give you a small bit of money like $20 a year to let them do that. I saw recently they are offering a thermostat that may be a replacement to the "Saver's switch" not sure yet. Xcel uses 3-7p for peak hours here and 1-3 for mid peak, weekends are all off peak. The transition won't finish for a few years as it requires a smart meter so it is in waves just starting last month. My house was built with one (for water and gas too believe it or not). Right now I set a timer in my car but yes you are right if we all charge at the same moment that will cause a demand, if the utility could perhaps stagger it that would help. Just as long as I have an override like I need to charge up for a road trip I am leaving for (so a rare occurance) that would be fine.

I like the idea of saving more money, it also means less peaker plants need to fire up which means less junk in the air. I am hoping utility storage like the Tesla megapack can help reduce peaker plants over time.

salyavin said:

Wow you clearly know a lot more than I do about this. What little bits I know come from a meeting I went to with the Colorado Energy Secretary and Xcel. I do know Xcel is preparing for it but yea does not have any date on offering it. Xcel does have a "saver's switch" they call it so they can turn down your air conditioner during peak and they give you a small bit of money like $20 a year to let them do that. I saw recently they are offering a thermostat that may be a replacement to the "Saver's switch" not sure yet. Xcel uses 3-7p for peak hours here and 1-3 for mid peak, weekends are all off peak. The transition won't finish for a few years as it requires a smart meter so it is in waves just starting last month. My house was built with one (for water and gas too believe it or not). Right now I set a timer in my car but yes you are right if we all charge at the same moment that will cause a demand, if the utility could perhaps stagger it that would help. Just as long as I have an override like I need to charge up for a road trip I am leaving for (so a rare occurance) that would be fine.

I like the idea of saving more money, it also means less peaker plants need to fire up which means less junk in the air. I am hoping utility storage like the Tesla megapack can help reduce peaker plants over time.

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Xcel is both behind, and ahead of the curve in many ways.

Smart meter upgrades in my area (Mountain View Electric co-op) are complete, or nearly so. This was driven by Tri-State Generation which supplies power to many of the rural co-ops in the region. They have done "Smart Charge" studies to learn charging patterns, but not taken things to the next level yet like Xcel is.

I like how Xcel is structuring their TOU plans, it seems reasonable that a majority of customers can realistically cut their utility costs with their plans. My co-op has a very poor plan for TOU, the only customers who could save are likely swing shift workers (not home from 5-10PM) and those with Solar + Storage.

SDG&E (San Diego) has an EV TOU plan that uses a separate meter on the EVSE circuit. BTW, SDG&E is known as the priciest utility in the country now, or right near the top. I think they are looking to phase that EV TOU plan out because the separate meter cost is born by the customer and not particularly popular. The trick is how to isolate the EVSE circuit from the rest of the home's energy use, and indirectly doing this via OCPP is a good alternative, particularly if the EVSE cost is subsidized. Manufacturer cloud services like Tesla and OnStar are another area with great potential if these companies can effectively implement systems to report and manage charging activity.

The duck curve (utility supply and demand curve) is an oversimplification of the problem utilities face. Demand is not linear, even on a system-wide basis. At times, even during off-peak, there can be short term surges that require adjusting supply to keep things in balance. This can be quite costly as capital intense generating facilities may be shut down, or output reduced and ROI suffers. It can be costly to adjust output as well, particularly if it means starting and stopping the generators. So, DR attacks the demand side to reduce the short term fluctuations that can be quite costly for the suppliers to meet. The $20 Smart Thermostat credit may seem like a pittance of compensation, but in reality, the impact is probably not even noticed by consumers. To the suppliers, it is quite possibly worth considerably more than $20/yr per participant, or at least could be when our regional demand increases.

The auction market for energy is an interesting topic. California ISO is a site where you can see some of the complexities of the art of balancing supply and demand in CA, one of the higher demand and supply constrained grid regions in the country. This page California ISO - Prices, Today's Outlook shows wholesale prices across the grid, pinpointed to small regions. During heat waves, the shortages on this map will show incredibly expensive $/MWh rates. It also illustrates the impact renewables have on current supply/demand across the Western US.

All of the strategies (TOU, DR, Solar + Storage) work together to "flatten the curve", meaning attempts to balance supply and demand to a steadier, predictable trend line reduce supplier costs considerably.

The same strategies are used in many industries to maximize ROI. In the call center business where I spent the last 20 years of my career, we developed multi-million dollar systems that were designed to flatten the supply/demand curve of call center agent staffing costs. Strategies involved queues (the annoying music on hold) to iron out short term spikes, complex staffing formulas, automation to answer some of the routine questions (press 1 to hear your current account balance), careful agent skill differentiation (make sure the first agent you speak to is most likely able to handle the problem), etc. It took a variety of strategies to balance things to minimize shortages (long queue times) without over staffing the call center for a peak demand period of less than an hour per day in many cases. The same holds for utility markets, it takes a variety of strategies to flatten the curve in order to maximize ROI and reliability.