Demand load controller

[Ampster]

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Running off grid is absolutely off-limits for the most of Arizona and SoCal. Who can afford 100kw/h or bigger batteries to cover entire daily demand of electricity in summer because of A/C and triple digits outdoor temperatures? 100kW Tesla PowerWall would be about $100k for such system. DIY battery system might be twice as cheaper but ROI would still take longer than those batteries last rendering such system economically prohibitive

It is not that bleak of an outlook in California at least for someone like me.
Tesla has sold a lot of Powewalls in California with the help of the Self Generation Incentive Program funds that improved the ROI. I am in Northern California but I still get hot days in the summer in Sonoma County. I had a reservation for a Powerwall but cancelled because I thought I could build a DIY system less expensively and not deal with the restrictions of the SGIP funding.

The first year and a half I broke even except for utility fixed costs, because of a rebate from a Community Choice Aggregator. That rebate is going away next year so I am investing in 30kWh of LFP batteries and going to self consume as much of my solar as possible. What I can't self consume I can use off peak rates to use up credits to charge my EVs. There is a lot of scepticism on this forum about my plan including my $125 per kWhr LFP batteries which one pundit has called counterfeit. I have verified the quality and expect to get 8 to 10 years before they degrade to 80% of capacity. Stay tuned. There are alternatives to the bleak outlook that the utilities have managed to leave us. I agree that those alternatives are out of reach for the general population..

[dstinson]

yea phx, SRP is not your friend when it comes to solar. Interestingly though APS has way more solar customers than SRP.

[phx]

Unfortunately SRP doesn't allow residential customers to have two meters and two separate payment plans on the same household. But they allow it to commercial customers. In such case demand solution can be as easy as having one solar meter and plan and another meter with "Basic" (non-solar) plan. Than automatic transfer switch with timer between two meters can make a deal. On non-peak time entire property has energy with solar plan and during peak time Basic plan provides more savings

Or if you have a really good neighbor, both households can benefit from such solution just by installing a cable over the fence. However in such case might be questions about legalities. So if would be best to consult with lawyer before doing that

[phx]

it would be nice if SRP could just become the demand controller. I would be ok with the utility company throttling my ac's at my own specified kwh. that would help them also during peak times. why cant i say use x kwh from 6p-8p. But the icing on the cake would be to use batteries (or natural gas generator) from 6-8 and then you can have them on at your own specified kwh.

When I was just planning my solar project last year, I was thinking why SRP is so passionate about DER with their customers. Now I see why. Demand charges is basically free money for them out of nothing. They have free energy from customers producing more power than they consume and still charge them big money just because those customers want electricity when they need it most. They do it just because they can. Fair? No and they are greedy sharks. Legal - yes and they do it just because they are monopoly. Money is the only their goal. So I guess they will help nothing to customers about demand mitigation and would deny any design developed for that purpose if asked for approval

Running off grid is absolutely off-limits for the most of Arizona and SoCal. Who can afford 100kw/h or bigger batteries to cover entire daily demand of electricity in summer because of A/C and triple digits outdoor temperatures? 100kW Tesla PowerWall would be about $100k for such system. DIY battery system might be twice as cheaper but ROI would still take longer than those batteries last rendering such system economically prohibitive

The only solution is to stay on grid but find a solution to mitigate demand charges. Then everything starts looking nice

[SunEagle]

I also would be ok with a (reasonable) flat fee from the utility company, I think they could charge a flat fee but also give you the option to have it waived or reduced if you provide them electricity to use elsewhere. That way both parties win. I am sure this will all change in the next 10 years. We also could see people removing themselves from the grid just like we did cable companies.

Most of the people that feel the POCO is charging them too much will be sad to hear that a very high percentage of grid connected customers are just fine with what they pay and get from them. Remember if you have an issue off grid you are on your own. While those connected to the grid still have a professional team of electricians to help resolve any issues.

The really sad part is there are a lot of customers on the West coast and in New England that are paying way too much for their power. Disconnecting from the grid may or may not force their POCO to charge less.

[dstinson]

I also would be ok with a (reasonable) flat fee from the utility company, I think they could charge a flat fee but also give you the option to have it waived or reduced if you provide them electricity to use elsewhere. That way both parties win. I am sure this will all change in the next 10 years. We also could see people removing themselves from the grid just like we did cable companies.

[Ampster]

it would be nice if SRP could just become the demand controller. I would be ok with the utility company throttling my ac's at my own specified kwh. that would help them also during peak times. why cant i say use x kwh from 6p-8p. But the icing on the cake would be to use batteries (or natural gas generator) from 6-8 and then you can have them on at your own specified kwh.

Yes, that is where I would I think utilities could use some forward thinking. Demand pricing in California is only common on commerial and industrial rates. I own an apartment complex that is residential but is classified commercial rate. I don't currently have any significant loads so I don't normally get charged any demand charges since the common area loads are garage door and gate openers and evening lighting. However some of my tenants have had EVs and that subjects me to demand pricing for an off peak 30 Amp load. My utility is forward thinking enough to make a special rate with no demand charges for EV charging but it requires a separate meter. Right now my one tenant with an EV is happy to pay the $25 a month for the convenience of being able to charge their EV at night. I have solar on that complex so it is not the cost of the power that bugs me it is the more or less fixed charge that adds to my bill. Right now it is not an issue but as more and more of my tenants start driving EVs I am going to have to manage those loads. Fortunately there are EVSEs that can be set up to share the loads so only one at a time gets the full load. When that one finishes the next in line gets more Amps.

[dstinson]

it would be nice if SRP could just become the demand controller. I would be ok with the utility company throttling my ac's at my own specified kwh. that would help them also during peak times. why cant i say use x kwh from 6p-8p. But the icing on the cake would be to use batteries (or natural gas generator) from 6-8 and then you can have them on at your own specified kwh.

[solardreamer]

The more economical solution maybe just to use a generator (using natural gas if you have it) with remote start and ATS on a timer to come on 6-8pm to power the A/C circuit during summer.

[phx]

Peak time with demand charges includes also few hours when there is absolutely no sun. SRP (Utility) charges $150 for 10kW demand in summer while price of kilowatt/hr off peak is 4 cent and on peak is 6 cent. In order to offset such demand charge with extra solar panels, it requires $150/0.06 = 2500kw/hr of additional solar production per month. So, basically existing system needs to be doubled in size. Even disregarding cost of such huge upgrade, there is no room for more panels on the roof. So idea of brute force fighting demand with number of panels doesn't look reasonable without demand mitigation during peak time

Unfortunately I don't have EV. So my question was just theoretical as a general idea for other readers of this topic who have it. More practical would be fine tuning A/C schedule during peak time based on momentary demand at each particular minute as Tier #1. It already can give some relief and doesn't need lots of investment. Then Tier #2 would be battery-based system with PWM in order to keep demand constant at predetermined limit (e.g. 3kW) instead of fluctuating from zero to 10kW. Otherwise in later case $150 demand charge from SRP will take place even if it happened once in a month

[solardreamer]

Yes that is intriguing from a load management standpoint which is what the OP was looking for. AFAIK it can be programmed to adjust charging Amps to follow solar generation. Long term that may be part of my grid zero plan. I will have to bone up on my Arduino skills.
However it does not address the question asked by @phx about using the EV battery to get through a peak period.

What he's talking about is conceptually possible using a grid-tied inverter with DC power from EV traction battery and coupled with power diverter to EVSE connected to the EV to avoid export to the grid. I doubt it will be cheaper than adding a few more PV panels to power the A/C.

[Ampster]

OpenEVSE has PV diverter functionality.

Yes that is intriguing from a load management standpoint which is what the OP was looking for. AFAIK it can be programmed to adjust charging Amps to follow solar generation. Long term that may be part of my grid zero plan. I will have to bone up on my Arduino skills.
However it does not address the question asked by @phx about using the EV battery to get through a peak period.

[solardreamer]

Amy ideas of using EV as backup energy source during peak time to mitigate demand? All Electrical Vehicles have powerful battery. But is it accessible for drawing energy out of it for "off label" purposes like feeding external inverter?

OpenEVSE has PV diverter functionality.

[Ampster]

There are some Chademo solutions out there but they are expensive. There were rumors that Tesla was going to enable access to their car packs but those proved not to be true.

In my opinion, the most likely things we will see in California will be DER programs to incentivize putting load on the grid during the belly of the duck curve. That could include EV charging and charging hybrid inverters and Powerwall like battery packs.

[phx]

Amy ideas of using EV as backup energy source during peak time to mitigate demand? All Electrical Vehicles have powerful battery. But is it accessible for drawing energy out of it for "off label" purposes like feeding external inverter?