New Here - Audacious Plans Afoot - 8000kWh System Coming Soon

PV panels are SO INEXPENSIVE I think it is cheaper to make more power than to buy more efficient appliances.
Would you worry about gas mileage of your Hummer if gas was $0.25/gallon?
PV generated power is $0.025/kWh.

Batteries, on the other hand, cost $0.05/kWh (of cycle life) or more, and running off grid you need inverters able to kick over large loads.
If 1:1 net metering is available, you're all good.
If your primary load is A/C (during daylight hours), just overpanel the hell out of your place. Go zero export if net metering not available.

Water heaters use so little power as to hardly matter for many. For instance, my tank type gas water heater + stove cost $8/month to operate. No point to getting instant on, heat pump, higher efficiency, or anything else.

If electric might cost me $80/month; they I'd consider alternatives. Like more PV panels, knocking the cost down to $4/month. Actually, I already have the panels, but not worth changing water heater to electric to use that.

8000 Kwh at $0.20/Kwh = $1600 per month

I'd move towards energy efficiency first before I'd consider building a system for 8000 Kwh per month.

Hedges said:

PV panels are SO INEXPENSIVE I think it is cheaper to make more power than to buy more efficient appliances.

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OP will need a very large system, that gets costly.

Hedges said:

Would you worry about gas mileage of your Hummer if gas was $0.25/gallon?

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If I was only making $1.00 per hour, then yes.

Hedges said:

PV generated power is $0.025/kWh.

Batteries, on the other hand, cost $0.05/kWh (of cycle life) or more, and running off grid you need inverters able to kick over large loads.
If 1:1 net metering is available, you're all good.
If your primary load is A/C (during daylight hours), just overpanel the hell out of your place. Go zero export if net metering not available.

Water heaters use so little power as to hardly matter for many. For instance, my tank type gas water heater + stove cost $8/month to operate. No point to getting instant on, heat pump, higher efficiency, or anything else.

If electric might cost me $80/month; they I'd consider alternatives. Like more PV panels, knocking the cost down to $4/month. Actually, I already have the panels, but not worth changing water heater to electric to use that.

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If power costs $0.20/Kwh it isn't $80. If power costs $0.10/Kwh, it isn't $80.

Now if he was paying $0.01/Kwh, then it would be $80/month.

k490 said:

That's lot of power probably going to need at least 100 450W panels and multiple inverters in parallel. Look up in your area see how large of a battery system your AHJ allows on the property. I noticed mine only allows 81kw max for residential which is about 5 EG4 power pros. Although I only glanced at it. How many panels did the local solar contractor quote you for? Trying to go completely off grid might not be worth it, but you can easily have a good battery backup system reducing non critical loads. You don't really need a pool pump if there is a power outage, or every AC unit running. Don't buy anything until you have a plan approved by your AHJ and power utility. Were you planning on using Greenlancer for the solar permit design plans?

If you connect a 50 amp inverter to a 200 amp panel have to reduce your grid main breaker so the max bussbar does not exceed 120%. 200 amp main bussbar max current allowed for that panel is 240 amps. You have to reduce the main to 190 amps to connect the 50amp EG4 18kpv. Not sure you can find a 190 main breaker. You would have to reduce the breaker down whatever you can get another method is conencting in the supply side before the main using a tap. You want to hire a electrican to do all this if you can find one who will work with you. You could upgrade the panels to 225 solar ready main service panels that gives you enough bussbar overhead. That's what lot of new homes coming with solar ready 225 amp panels.

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If he feeds 2 or 3 18k inverters from a 400a disconnect, then there is no 120 rule.

Hedges said:

PV panels are SO INEXPENSIVE I think it is cheaper to make more power than to buy more efficient appliances.
Would you worry about gas mileage of your Hummer if gas was $0.25/gallon?
PV generated power is $0.025/kWh

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I don't see that as an apples to apples comparison.

PV panels are dirt cheap yeah, but what about the rest of the system? 800kWh of storage for 3 days of autonomy???? Not to mention needing MULTIPLE inverters to be able to handle starting 4x 5 TON AC units at the same time! Replace the ACs with inverter style units or mini split/heat pumps and you reduce surge required and total PV/Battery required. You end up cutting costs in HALF I bet!

Hedges said:

Water heaters use so little power as to hardly matter for many. For instance, my tank type gas water heater + stove cost $8/month to operate. No point to getting instant on, heat pump, higher efficiency, or anything else.

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I agree with you here. My natural gas WH is only a few years old, and my gas bill including my gas stove and gas furnace is only $35/mo on average. But when the WH needs to be replaced, im putting in a Heat Pump unit for sure.

AutoMater said:

Install Emporia energy monitors in all panels to make sure I am not DRAWING more than 100amp per any panel

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Does Emporia have DC current transducers and if so is there an option to connect that many to the Emporia? A good inverter will give you useful system performance and If I understood correctly that this was a ground mount, you would have access to individual panel cables to diagnose any panel issues.

Lt.Dan said:

I don't see that as an apples to apples comparison.

PV panels are dirt cheap yeah, but what about the rest of the system? 800kWh of storage for 3 days of autonomy???? Not to mention needing MULTIPLE inverters to be able to handle starting 4x 5 TON AC units at the same time! Replace the ACs with inverter style units or mini split/heat pumps and you reduce surge required and total PV/Battery required. You end up cutting costs in HALF I bet!

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Very true, if you need to operate off-grid.

"If 1:1 net metering is available, you're all good.
If your primary load is A/C (during daylight hours) ..."

Hardware alone (DIY) for GT PV I previously put at $1/W, makes power for $0.025/kWh (amortized over 20 years.) Maybe can be done for $0.50/W, $0.0125/kWh.

Batteries and inverters with sufficient surge may add $0.075/kWh, and only store what you will use in the next day or so.

Lt.Dan said:

I agree with you here. My natural gas WH is only a few years old, and my gas bill including my gas stove and gas furnace is only $35/mo on average. But when the WH needs to be replaced, im putting in a Heat Pump unit for sure.

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(neglecting PV for the moment), do you calculate that HPWH will cost less to operate than gas?
How does it compare using your PV cost per kWh?

Hedges said:

(neglecting PV for the moment), do you calculate that HPWH will cost less to operate than gas?

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I know this was directed at another member. but in my case I have always compared the cost of HPWH with solar to gas and clearly HPWH wins out. Plus the flexibility to control the timing including vacation mode which can be done remotely. We travel a lot so that is a real feature.

Ampster said:

Does Emporia have DC current transducers and if so is there an option to connect that many to the Emporia? A good inverter will give you useful system performance and If I understood correctly that this was a ground mount, you would have access to individual panel cables to diagnose any panel issues.

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Sorry I meant installing them in all of the 200amp AC electrical panels

AutoMater said:

I meant installing them in all of the 200amp AC electrical panels

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I love the data and funtionality from my Emporia. I also got the Emporia EVSE which can modulate the current the EVs draw so I can use excess solar to charge my EVs.

Hedges said:

Very true, if you need to operate off-grid.

"If 1:1 net metering is available, you're all good.
If your primary load is A/C (during daylight hours) ..."

Hardware alone (DIY) for GT PV I previously put at $1/W, makes power for $0.025/kWh (amortized over 20 years.) Maybe can be done for $0.50/W, $0.0125/kWh.

Batteries and inverters with sufficient surge may add $0.075/kWh, and only store what you will use in the next day or so.

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It's becoming far more uncommon for 1:1 net metering. I have it, but also on a TOU. Most solar happens in afternoon, and big loads (AC usage) happens in the late afternoon/evening. So my 1 credit of solar during the afternoon is only work 1/3 credit in the evening. Now batteries DEFINITELY make sense.

Hedges said:

(neglecting PV for the moment), do you calculate that HPWH will cost less to operate than gas?
How does it compare using your PV cost per kWh?

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For my personal use case, Solar covers all of my loads, so the HPWH wins every day, because I'm paying $0/BTU.

I did do a little research a while back, and im not sure how accurate the numbers are, but if (with no PV) electricity cost is higher than $0.18/kWh, then the HPWH is typically cheaper to run. My electricity in the off peak is $0.24/kWh and on peak is $0.60/kWh. So yes HPWH is always cheaper for me.

My recent numbers were electric resistance heating is 8x the cost of gas.
Heat Pump might cut that premium in half or so?

Prices fluctuate, but when I checked those were the Bay Area rates I saw.
Think gas shot up a couple years go but back to normal for now.

Turn-key PV + heat pump could be break-even with gas (therefore not worth tying up cash) but DIY PV could cost a fraction as much, would be a win.
Then, I might stick with resistance heating (KISS) at least so long as I have net metering, no battery costs in the equation.

I'm putting PV on my new place, will keep gas appliances but add electric heat as a switchable option. Might use heat pump for conditioning previously unconditioned space, at least if cooling is also desired.

Hi

i am in a kind of close situation with a 8200 sq feet house, 8 AC (2 fna and coil units of 5 tons each and 6 mini split of 1.5 and 2 tons), pool pumps, etc etc House is NOT insulated and i am in Cancun... AC is required all year long. I did serious efforts on energy consumption by investing in all inverter equipments, led lighting, smart systems etc etc. My biggest energy consumption is 3000 kwh per month when it is stupid hot and.humid. I have 10 kw of solar i am installing 18 kw more with a 18k and 60 kwh of Pytes batteries and i think I won't be able to use the 130 kwh a day i should get average.... I think you should first invest into tech that will reduce your energy needs and then elaborate on your system, you could/should save then 1 ton of money....

In my original post I asked for thoughts or advice about connecting multiple batteries together with bus bars and sharing them with ALL inverters. Has anyone done that? Any thoughts or advice? I will have 3 inverters, one for each 200amp electrical panel, and possibly 2 per panel. Then I will have that 3 times (1-2 inverters for each of 3 200amp panels). So I am trying to figure out how to share all the batteries across all the inverters to avoid effectively having 3 separate systems.

Also, another option might be to master/slave all the inverters needed and dump all the power into some sort of trough that then feeds all 3 of the 200amp panels. Is that maybe a better way to do it?? (For what it's worth, the power now comes from the meter, goes into a trough, and breaks into the lines that go to the three 200 amp panels)

I think that should work fine, and PV harvested by any is available in batteries for all.
So long as multiple A/C or other big motors don't try to start at the same time, the larger battery will help with that. Try to sequence such motors in some way.

Several of the big hybrids support a number of inverters in parallel, which means they would agree on how to charge battery. You could parallel all inverters and feed all panels (as your second paragraph indicates), or you could keep AC outputs separate; I don't think they care either way.

My system has 4x SI 6048US (120V each) wired 2p2s. I could have two separate 2s systems sharing battery and communication bus, and I think that would work fine except for one situation: If each has AC coupled PV (my system does, it has Sunny Boys), and if the AC coupled wattage exceeded what the SI 6048US could convert to DC, I think that would be a problem.

That's not likely if you use AIO, with mostly DC coupled PV and maybe a small amount of AC coupled.

AutoMater said:

In my original post I asked for thoughts or advice about connecting multiple batteries together with bus bars and sharing them with ALL inverters. Has anyone done that? Any thoughts or advice? I will have 3 inverters, one for each 200amp electrical panel, and possibly 2 per panel. Then I will have that 3 times (1-2 inverters for each of 3 200amp panels). So I am trying to figure out how to share all the batteries across all the inverters to avoid effectively having 3 separate systems.

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In fact, that’s how EG4 ESS (18Kpv plus PowePro) is supposed to be wired. The internal bus bars are good for 600A so you may not need external ones.

Please note (again) that 18Kpv is essentially a 50 amp (AC) inverter, and needs two PowerPro batteries per inverter to provide the DC power peaks. I don’t think one 18Kpv inverter per 200A AC panel is going to work very well for you.

You really need to do an energy audit to know what your peak (KW) load is, and your daily(?) KWHR requirements are before throwing hardware in.

I am getting conflicting info from the local solar guy, and signature solar.

You guys seem to be saying that I should be able to do it more like the following, yes?

Or should we master / slave all inverters together?

I’m struggling to figure out how to go about this “the right way”.

Are all three inverters co-located? If so, parallel the inverters and tie the battery banks together. If not, treat them as separate houses.

And one 18Kpv may be too small for a 200A panel. Sorry I forgot to mention that before

wpns said:

Are all three inverters co-located? If so, parallel the inverters and tie the battery banks together. If not, treat them as separate houses.

And one 18Kpv may be too small for a 200A panel. Sorry I forgot to mention that before

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Yes, all three of the 200amp panels are together 2 feet from each other.

Assume there will be 2 inverters for each 200amp panel if that is what is needed.

Could you be more verbose about "parallel the inverters and tie the battery banks together". If I parallel the inverters wouldn't that mean I need to dump it all into a bus bar and feed the three panels from there? How can I "tie the battery banks together"? According to the manual only 3 batteries should be paralleled per inverter. I need like 10-12 (final number TBD)

AutoMater said:

Could you be more verbose about "parallel the inverters and tie the battery banks together". If I parallel the inverters wouldn't that mean I need to dump it all into a bus bar and feed the three panels from there? How can I "tie the battery banks together"? According to the manual only 3 batteries should be paralleled per inverter. I need like 10-12 (final number TBD)

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Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

wpns said:

Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

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To be clear, the way it works now is the grid power goes into a trough where there are bus bars that connect the meter to the lines that run to each of the 3 disconnects (that then go to the panels inside the house).

So I suppose this would stay the same except from those bus bars I would run to the inverters, then out of the inverters and to another set of bus bars, then back into the disconnects. Or, how do the

wpns said:

Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

Click to expand...

Thanks a lot for this. I didn't even see your reply till after I called Signature Solar and talked to their techs today and they basically said the same thing you just said.

What I am thinking about right now and trying to figure out how to deal with is what all pieces should be where. Here is something I drew just now. I took a look on ebay (just to gauge what a 600 amp panel costs) and holy cow! I am hoping you guys or one of the electricians has some sort of idea about how to go about this cheaper.

I am also including an image of my current electrical setup. The trough in the bottom right is where the grid power comes in from the meter (left). In the trough there are bus bars where they just connect together those wires with the wires that are going into the 3 disconnects you see above it.

I am imagining coming from the meter, through the trough, out the bottom of it, in conduit over to where the solar stuff will be, into the 600 amp panel I have drawn (or possibly 6 disconnects if that is possible / easier / cheaper), then you can see the rest on the drawing. The wires from the "combiner box" exiting the inverters would go in conduit, back into the trough, and back into the disconnects going into the house.

Thoughts?

Sorry I forgot to mention: Your first step should be an energy audit.

600 amp service split to 3 300A panels is an insane amount of power (144KW), but it’s unlikely you actually need all that. You paid a fortune for your current setup, you either need to do it again with 12(!) inverters in the middle or figure out what you actually need.

I fell into this trap myself, I’ve got a 200A service with a 25KVA (100A) transformer, so I was able to significantly downsize my wiring requirements (and saved thousands in wire costs) when I moved my transformer. I’ve got a neighbor with a 400A feed who shares a 25 KVA transformer with two other houses. Know what you need _first_.

These are likely a good part of your high energy usage. And whoever installed them grossly violated the minimum distance between units. Amana calls for a minimum of 20" between units for residential and 24" for light commercial. You should be going by light commercial recommendations with 4 units. The poor airflow around the units is going to really cut down on efficiency. They also look like they're old enough that replacement wouldn't be a bad idea in general.