On Peak and demand shaving from electric bill

[k490]

Trying to figure out if it's feasible to try and off load my highest power consumption appliances to a battery and inverter system for 3 hour a day during peak usage rate. I live in the desert it's hot been over 115F for a while now. My biggest part of my bill is a demand charge. This is where they monitor for the highest 15 minutes a day of KW usage and multiply that by a number. The result is my bill is $375 of that the demand part is $189 of it. Even in the winter we don't even use the heat pump the demand charge can be $80-$100 with a total bill of $189.

My 4-ton heat pump draws 20 amps while running I measured it when it was 115F outside 4800 watts I will install a soft start keep the startup current down. If I charge during the off-peak at 6 cents a KW into 30kwh of batteries that should get me through the 3 hours. The question is does any inverter exist that can connect in and add power to the system or is it like I think any off-grid inverter will need to be re-wired between the load and the grid.

I looked into sever rack batteries the ROI is too high but DIY building from cell packs might be feasible 15kw at 48V is $2000 shipped about 12 cents a watt. I know those Chinese sellers might be a problem let's just set that aside for now. I'm just looking at the numbers and how can I wire it what the ROI would be. It would be nice if something could just wire in parallel to the grid mains and add power when it senses power being pulled. I know that is what a grid-tie seems like there is no inverter that grid-ties like that with batteries.

 

[DIYrich]

Sol-ark has grid support feature that seems to be what you want.

Don't forget the 30% federal tax credit.

 

[k490]

Sol-ark has grid support feature that seems to be what you want.

Don't forget the 30% federal tax credit.

Reading the Sol-ark manual they have a CT sensor clips around the main wires from the meter that tells the inverter no back-feed to the grid but limit power to home, or grid peak shaving. That looks like something should work for me.

 

[k490]

Doesn't save money to shift peak here I just got hit with an adjuster fee for pulling too much overall power even though the on peak went down and off peak went up. The total usage for August month went up from last year 3628 KWH this year 3805KWH hit me with almost $50 more in a fee. Only way to save money is to put in solar panels which I'm going to do now.

 

[kram]

@k490 I am in the same boat as you are, need to reduce my demand charge and peak rate. Any hybrid system with CT clamps will accomplish what you are needing. Some of my research indicates that i can use a Schneider XW Pro, the EG4 K18 or EG4 8KW

 

[Watts Happening]

Reading the Sol-ark manual they have a CT sensor clips around the main wires from the meter that tells the inverter no back-feed to the grid but limit power to home, or grid peak shaving. That looks like something should work for me.

The Sol-Ark will 100% do what you’re wanting to do, no question about it. I do the exact same thing. You can easily set what time of day you want it do so that. IE you could say from 3-6pm you want ALL power to the house to come from batteries, or up to X watts etc.

Personally I have mine feeding a critical loads panel that is basically our entire house, but it can be configured to do your whole house as well. I tried doing this with the EG4 18Kpv and it was a disaster, that said I’m sure it will be a fine unit as time moves on and they get their firmware figured out. If you’re looking to buy and do this right now, I can’t recommend Sol-Ark enough. If this is 6 months out or more, I’d highly suggest seeing what progress has been made on the EG4 unit, it was very well built and has a ton of potential, but right now isn’t ready for what you’re wanting to do.

 

[Watts Happening]

@k490 I am in the same boat as you are, need to reduce my demand charge and peak rate. Any hybrid system with CT clamps will accomplish what you are needing. Some of my research indicates that i can use a Schneider XW Pro, the EG4 K18 or EG4 8KW

See my prior post about what I think makes sense now, either way, my general understanding of the EG4 8kw is that it’s a train wreck. Wills videos make it out to be a complete disaster, but I don’t know if they’ve had major improvements or not. It certainly was an attractive price and looked to be a nice sized unit though.

 

[k490]

I looked at the Sol-Ark manuals all the examples of wiring diagrams had the load terminals connected to an Essential loads panel. Whatever is connected to the essential loads panel gets to use solar power. The main panel still connected to the grid.

 

[Watts Happening]

I looked at the Sol-Ark manuals all the examples of wiring diagrams had the load terminals connected to an Essential loads panel. Whatever is connected to the essential loads panel gets to use solar power. The main panel still connected to the grid.

You can basically configure it to do either: only power the essential loads panel, or, power both the essential loads panel AND feed back to the main panel.

The EG4 does this as well, again I didn’t have a good experience with it, but it’s certainly what it is designed to do.

 

[k490]

You can basically configure it to do either: only power the essential loads panel, or, power both the essential loads panel AND feed back to the main panel.

The EG4 does this as well, again I didn’t have a good experience with it, but it’s certainly what it is designed to do.

I'm assuming I will need to contract with my utility if I plan to use this since it's a grid tie even if I don't plan to sell power back to them.

 

[Watts Happening]

I'm assuming I will need to contract with my utility if I plan to use this since it's a grid tie even if I don't plan to sell power back to them.

You know, I really don’t know the answer to that. My gut tells me you probably do, as you’re clearly making circuit changes and I’d be rather surprised if your local jurisdiction didn’t want to know about that (and collect a nice little fee).

That said, I think it’d be smart to reach out to each of the manufacturers and see what they have to say. They may also have users in your area that have gone through the process.

 

[k490]

You know, I really don’t know the answer to that. My gut tells me you probably do, as you’re clearly making circuit changes and I’d be rather surprised if your local jurisdiction didn’t want to know about that (and collect a nice little fee).

That said, I think it’d be smart to reach out to each of the manufacturers and see what they have to say. They may also have users in your area that have gone through the process.

I saw your mega thread with the issues trying to get the 18kpv to peak shave. I don't see the point in even connecting it to the grid anyway if you ever want to use it for power outages that will only work on the critical load panel. I can use a transfer switch panel, and not bother with peak shaving from the main panel. That way I can setup a transfer switch just transfers in stuff I want on solar, and battery. Obviously, I don't want any peak grid power going to high load devices.

I'll probably go with Sol Ark one thing I like is I can buy it from local solar company Santan Solar they sell Sol Ark also looking at Schneider. You mentioned possible fine from back feeding in that other thread are you in Arizona?

 

[webbbn]

I'm also in Arizona and am trying to figure out if it would be possible to do some demand shaving. Unfortunately I have 2 HVAC. I haven't checked their exact load, but they're rated (according to the sticker on the compressor) at 27A and 16A. I just had them serviced and the repairman also suggested a soft start on the larger one, as it was pulling around 100A at startup.

My provider is Tucson Electric Power, and they have both demand and non-demand TOU plans, but the only one that would have any real payoff is the super off-peak demand TOU, that has very low rates outside of peak usage, but a huge penalty for usage within peak time. They charge a monthly penalty each month for the highest single peak demand of $10-14 per KW. I assume that's calculate on the total peak usage for a single day, but I'm not entirely sure.

In any case, if I could use as close to zero during peak times as possible, I calculate that I could save close to1/2 of my current electric bill.

Not to derail this thread, but I would also be interested in hearing any suggestions on programmable thermostats / HVAC control. Just pre-cooling before peak and lowering cooling a bit during peak could have some significant payoff, and ensuring that both AC units don't start at the same time while on battery would be really nice.

I've been wondering if the 6.5kw EG4s would work. My impression is that they can be expanded in parallel, which could allow for expansion if 12/13kw is not enough.

 

[DIYrich]

In any case, if I could use as close to zero during peak times as possible, I calculate that I could save close to1/2 of my current electric bill.

sol-ark has a "Grid Peak Shaving" parameter. Let's say you get a Peak Demand charge between 3pm-6pm for anything over 5kW. You could set the parameter to 4500 watts (something under the peak). I'm not sure how you would dovetail that with TOU settings. Maybe under TOU, you set the battery discharge limit to 100% (won't go below 100%) for any period other than 3-6pm. During that period, you let the battery go down to 0% (or whatever your floor is).

You may also think about a Load Manager. Maybe it would only allow one A/C to run at a time during peak hours.

You also might want to see how peak is calculated. It might be 5 or 15 minute periods, and not instantaneous peak.

Not to derail this thread, but I would also be interested in hearing any suggestions on programmable thermostats / HVAC control. Just pre-cooling before peak and lowering cooling a bit during peak could have some significant payoff, and ensuring that both AC units don't start at the same time while on battery would be really nice.

Any smart thermostat can be set to cool tp 70 degress, say 1 hour prior to Peak TOU charge, Go up to 80 during peak. and back to normal after that.

 

[k490]

I'm also in Arizona and am trying to figure out if it would be possible to do some demand shaving. Unfortunately I have 2 HVAC. I haven't checked their exact load, but they're rated (according to the sticker on the compressor) at 27A and 16A. I just had them serviced and the repairman also suggested a soft start on the larger one, as it was pulling around 100A at startup.

My provider is Tucson Electric Power, and they have both demand and non-demand TOU plans, but the only one that would have any real payoff is the super off-peak demand TOU, that has very low rates outside of peak usage, but a huge penalty for usage within peak time. They charge a monthly penalty each month for the highest single peak demand of $10-14 per KW. I assume that's calculate on the total peak usage for a single day, but I'm not entirely sure.

In any case, if I could use as close to zero during peak times as possible, I calculate that I could save close to1/2 of my current electric bill.

Not to derail this thread, but I would also be interested in hearing any suggestions on programmable thermostats / HVAC control. Just pre-cooling before peak and lowering cooling a bit during peak could have some significant payoff, and ensuring that both AC units don't start at the same time while on battery would be really nice.

I've been wondering if the 6.5kw EG4s would work. My impression is that they can be expanded in parallel, which could allow for expansion if 12/13kw is not enough.

I already have the TOU plan my utility APS hitting me with adjuster fee of extra $50 for using more total power even though I dropped my on peak usage. The demand fee is $16 in the summer even worse than yours. Tuscon electric is little better then APS.

I'm still in the process of figuring out if solar is even feasible for me. Where I would get the best bang for the buck, I can see why most just put up some panels and do a grid-tie only because the ROI is shorter when using a solar contractor not compared to DIY. It's a simple system when the sun is up your saving money as long as your using power during the day.

I'm even looking into a small inverter that will run my pool pump Growatt makes one. It pulls about 2500 watts when running since it runs daily if you add up the .06 cents a KWH over a month it's 50-70$ a month to run a pump.

It's easy to get carried away with this because something cool about making power from the sun doing it DIY can save money. The reality is the amount of batteries it takes to make a big difference will cost lot of money. Then have to cool the inverter we are in such a hot climate. Off-grid ROI is good in places where the climate is not so extreme. Building a system that works for summer it's almost useless in the winter here we get 5-10 days of below 40F. If don't care about backing up power when there is an outage, then could just forget about the critical load panel.

 

[webbbn]

You may also think about a Load Manager. Maybe it would only allow one A/C to run at a time during peak hours.

You also might want to see how peak is calculated. It might be 5 or 15 minute periods, and not instantaneous peak.

Any smart thermostat can be set to cool tp 70 degress, say 1 hour prior to Peak TOU charge, Go up to 80 during peak. and back to normal after that.

I found a description of the demand charge in the corporate rate plans, and it is defined at the maximum usage for any single hour within peak hours, so I don't think surges would affect it too much.

That said, they just passed a rate increase that increases the rate during peak times by 89%!

 

[webbbn]

I already have the TOU plan my utility APS hitting me with adjuster fee of extra $50 for using more total power even though I dropped my on peak usage. The demand fee is $16 in the summer even worse than yours. Tuscon electric is little better then APS.

I'm still in the process of figuring out if solar is even feasible for me. Where I would get the best bang for the buck, I can see why most just put up some panels and do a grid-tie only because the ROI is shorter when using a solar contractor not compared to DIY. It's a simple system when the sun is up your saving money as long as your using power during the day.

I'm even looking into a small inverter that will run my pool pump Growatt makes one. It pulls about 2500 watts when running since it runs daily if you add up the .06 cents a KWH over a month it's 50-70$ a month to run a pump.

It's easy to get carried away with this because something cool about making power from the sun doing it DIY can save money. The reality is the amount of batteries it takes to make a big difference will cost lot of money. Then have to cool the inverter we are in such a hot climate. Off-grid ROI is good in places where the climate is not so extreme. Building a system that works for summer it's almost useless in the winter here we get 5-10 days of below 40F. If don't care about backing up power when there is an outage, then could just forget about the critical load panel.

Actually, I got started looking at this after being without power for a couple of days in 112 degree heat! I'm not going to be able to put enough battery on to make it through multiple days with AC, but having some solar and some battery backup would have been better than nothing.

The solution that I'm currently looking at is having a modest set of solar panels installed along with a good inverter that I can add battery to as needed. I just want to make sure I put in the right inverter.

I got a couple of quotes, and one proposed using a SolarEdge inverter, which looks decent, but the Sol Ark looks much better and more DIY friendly for later expansion.

 

[k490]

Actually, I got started looking at this after being without power for a couple of days in 112 degree heat! I'm not going to be able to put enough battery on to make it through multiple days with AC, but having some solar and some battery backup would have been better than nothing.

The solution that I'm currently looking at is having a modest set of solar panels installed along with a good inverter that I can add battery to as needed. I just want to make sure I put in the right inverter.

I got a couple of quotes, and one proposed using a SolarEdge inverter, which looks decent, but the Sol Ark looks much better and more DIY friendly for later expansion.

Are you planning on using a solar contractor, and doing a grid-tie hybrid setup with your utility? I looked into that with APS they will not allow you to build over 15kw with a 200-amp panel. They also don't allow changes to number of panels or a battery size unless you get approval first.

If you want back up power buy a Generac 26kw with a whole house transfer switch cost about $7000. Then you don't have to worry about a power outage we rarely have them here all underground wiring. If we had more, I would buy one of those. Could have it charge a battery only run when the battery was depleted.

 

[DIYrich]

I got a couple of quotes, and one proposed using a SolarEdge inverter, which looks decent, but the Sol Ark looks much better and more DIY friendly for later expansion.

If you go with SolarEdge, you are mostly stuck with using their products, which gets quite pricy. You can attach anything to the Sol-Ark. If you want a sol-ark quote, go to their website to find an installer near you.

 

[webbbn]

Are you planning on using a solar contractor, and doing a grid-tie hybrid setup with your utility? I looked into that with APS they will not allow you to build over 15kw with a 200-amp panel. They also don't allow changes to number of panels or a battery size unless you get approval first.

If you want back up power buy a Generac 26kw with a whole house transfer switch cost about $7000. Then you don't have to worry about a power outage we rarely have them here all underground wiring. If we had more, I would buy one of those. Could have it charge a battery only run when the battery was depleted.

The power outages was just the proverbial straw. My original intent was an off-grid battery to support time of use, but if that requires a $6k+ inverter setup, might as well add panels, which I can't/don't want to attempt to install myself.

On the positive side, the huge rate increase that was just passed really helps with the ROI calculation!