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

[k490]

No, i'd said in my original post that I have used as high as 8000 kWh per month. Then after I got the charts and posted them it is around 5000 - 7000 kWh per month depending on the month.

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.

 

[Hedges]

That’s interesting. I haven’t run the math yet but I wonder if it would make more sense to do something like that so you get the integrated bus bars vs the external ones when using the wall mount batteries. And it’s perhaps a little more protected from the elements this way.

That enclosure is made to hold rack batteries, 100 Ah each. There are larger 280 Ah rack mount (I think). The PowerPro is an attractive package, 280 Ah available in an outdoor enclosure, with heating (but no insulation). Also wall mount indoor.

280 Ah with fewer strings in parallel is the way to go for now. 560A cells have been announced.

I noticed mine only allows 81kw max for residential which is about 5 EG4 power pros.

Some batteries have BMS that talk to each other, aggregate their requirements and tell inverter what voltage and current to charge with. Other systems run open loop, inverter/charger pre-set with values. So long as each battery string has separate BMS to disconnect, that avoids the (catastrophic) failure where others dump into battery with failed cells.

Ideally each battery string would be independently connected, like each with its own inverter. Tesla PowerWall for instance. This requires good coordination to form and support grid. When HV (like 400V) strings are used it can be pretty high capacity. BYD sells a 32kWh battery; would be much higher if made with 280 Ah cells.

 

[Lt.Dan]

I gotta admit, I saw the thread title of 8000kWh and assumed you meant 8000kWh of Battery Storage I thought @timselectric was finally going to get a run for his money!!

Very interested in seeing this project come to fruition as my parents are in a similar situation.

Good Luck! Welcome to the Forum!

 

[jpwhit]

Maybe a little but not by half or anything. It is a 7000sq ft home with 3 floors, 4 AC's, pool pumps, home theater, etc etc. I am aiming for convenience as much as self reliance and resilience - I would like to keep living my life whether the grid power is there or not.

However, I have already been noticing things that I have began to change, even before having the energy monitors in place and taking action on them. I realized my pool pump was running 8 hours a day and changed it to 5 (which is about what it needs to run), I had a ton of florescent under counter lights and just ordered all new LED ones, and other stuff like that. But, I will only be able to get things so low without making life less enjoyable or creating a pain to manage it.

Another thought I have had is that even if I do not have enough battery to last through a night in the event of a grid outage (until I get more batteries) I COULD flip off breakers to extend the batteries. (Critical Load panels are not interesting to me for a lot of reasons)

I'm not sure you're correct about investing money to reduce you load. One of my houses is a similar size and I don't use anywhere close to the amount of power that you're using. Looking at your usage graphs, it makes me think a lot of your usage is on HVAC. Can you post the model numbers of your 4 HVAC units?

About 5 years ago, I installed three 4-Ton Trane XR20 Heat Pumps along with natural gas air handlers for dual fuel heating. That cut my heating and cooling costs in about half. I also have 3 super high efficiency mini-split systems to more efficiently heating and cooling of selected spaces.

Investing in more efficient HVAC systems will probably save you money on the size/cost of the solar / ESS system, that along with energy savings will probably cover a good bit of the HVAC upgrade costs. Especially if the HVAC systems you have now have any age on them and will need to be replaced anyway in the next 5-8 years.

Are you heating your pool? If so, is it a heat pump based unit and what is the efficiency rating on that unit?

 

[Lt.Dan]

The cost to reduce energy consumption, and increase efficiency of all your appliances, is ALWAYS cheaper than more Solar/Battery/Inverters.

Before designing a system, I always try to look at where you can cut consumption first, especially when it's a situation like a 10 year old, 6 SEER, 4 ton AC unit that you don't know how long it's going to last anyways. Or the 15 year old electric water heater that could be replaced with a heat pump model. If you think it's going to have to be replaced soon anyways, might as well do it before it goes bad, and get a highly efficient unit to replace it with.

 

[Hedges]

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.

 

[Zwy]

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.

 

[Zwy]

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

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

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

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

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.

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.

 

[Bkord]

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.

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

 

[Lt.Dan]

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

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!

 

[Lt.Dan]

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.

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.

 

[Ampster]

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

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.

 

[Hedges]

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!

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.

 

[Hedges]

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.

(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?

 

[Ampster]

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

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.

 

[AutoMater]

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.

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

 

[Ampster]

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

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.

 

[Lt.Dan]

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.

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.

(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?

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.

 

[Hedges]

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.

 

[Vince Mex]

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....