Home energy storage advice needed

[vicwill]

I own a very energy efficient 100% electric home in Massachusetts (rated .31 Ach50) with a Solar Edge 7.68 kWp peak power system that is grid tied and has net metering. My max power usage was last Feb at 1093kWh/mo and my lowest use was in May at 332KWh/mo. Based on my electric bill, my average use is 630kWh/mo. My heat pump uses about 460 kWh, Fridge 1Kwh/d and my water heater 560kWh, TV 135 kwh, laptop 65 kWh. I have all LED lighting.
I am looking for a cost effective home battery backup system.
My Options are
1. A grid tied hybrid inverter with back up batteries installed outside or
2. Critical load panel that can be used with back up battery usage during an outage.

I have priced out an EG4 system with a 12K PV hybrid inverter, EG4 Grid Boss MID, EG4 all weather 48V/14.3kWh battery. system approx $10,000 delivered not counting installation.
Massachusetts has a program that has a 0% loan and has a incentive for reducing/shifting electricity during peak demand periods in the summer but I would need to use Sol-Ark as an eligible inverter ($5-7K just for the inverter) installation but could then use the EG4 battery.
I don't know what it costs to install either of these 2 systems with battery back up.
What would it cost to just install a critical load panel with a battery backup?
I would welcome any input!

 

[chrisski]

First, I'd check to be sure it does not move you from a favorable rate plan where you have now to one much less favorable to the consumer. Electric companies have gotten smart on how to get their money since several years ago people received NEM 1 installs receivign a 1 kWh for 1 kWh credit for power produced to the NEM 3 type rated now that charge the consumer a fixed rate per kWh of panels on the roof whether and buy excess power back at a rate 1/3 rd of what you pay. The NEM 3 makes a payback period almost undoable.

What would it cost to just install a critical load panel with a battery backup?

My guess would be several thousand dollars, perhaps $20k. It really depends. I expect it to be less than that rather than more.

My price for a battery installed is $12k per 10 kWh - 15 kWh. There is a lot that goes into a coded install. I'm guessing the panel with circuit breakers will be an additional $5k. This includes cutting the wall out and repairs and an inspected install.

Growing up in Massachusetts and now in Arizona, I'm amazed at how few kWh you use for an all electric house, especially for heat in the winter. In AZ, I estimate my daily AC is 100 kWh. Between 2 ACs, they use 5 kW per hour on average per day in the summer. Up to 120 kWh per day. I just measrured my fridge and it uses 4 kWh per day.

EDIT: Equipment cost is a small cost of the overall install and I would not recommend having an installer put in equipment he is not familiar with and learn on your dime. If you contact EG4 by DM on this board, they will provide you local installers if you choose to go that route.

 

[y0bailey]

First, I'd check to be sure it does not move you from a favorable rate plan where you have now to one much less favorable to the consumer. Electric companies have gotten smart on how to get their money since several years ago people received NEM 1 installs receivign a 1 kWh for 1 kWh credit for power produced to the NEM 3 type rated now that charge the consumer a fixed rate per kWh of panels on the roof whether and buy excess power back at a rate 1/3 rd of what you pay. The NEM 3 makes a payback period almost undoable.

My guess would be several thousand dollars, perhaps $20k. It really depends. I expect it to be less than that rather than more.

My price for a battery installed is $12k per 10 kWh - 15 kWh. There is a lot that goes into a coded install. I'm guessing the panel with circuit breakers will be an additional $5k. This includes cutting the wall out and repairs and an inspected install.

Growing up in Massachusetts and now in Arizona, I'm amazed at how few kWh you use for an all electric house, especially for heat in the winter. In AZ, I estimate my daily AC is 100 kWh. Between 2 ACs, they use 5 kW per hour on average per day in the summer. Up to 120 kWh per day. I just measrured my fridge and it uses 4 kWh per day.

EDIT: Equipment cost is a small cost of the overall install and I would not recommend having an installer put in equipment he is not familiar with and learn on your dime. If you contact EG4 by DM on this board, they will provide you local installers if you choose to go that route.

I agree on the kWh in the winter. I'm in NC and it's mild here, by my top expense come JAN/FEB is heating. Granted there are much more efficient heat pumps for heating than my unit, but OP are you sure you don't have some gas supplementation?

Granted I have a 3000sq ft house so size matters...but that is impressive.
I can't wait for my heat pump to finally die so I can swap it for a more efficient model.

 

[SunDave]

Hi vicwill,
Your math is not mathing. You may want to double check what you typed in the post because the numbers are not making sense. You stated that your max use was 1093 kWh for the month, but then the systems you listed individual usage for adds up to 1250 kWh alone, without all of the odds and ends that are not listed.

I have a home battery backup system. The terms cost effective, and home battery backup don't really go together. Not a code compliant setup anyhow. A small generator like my Harbor Freight inverter 8750 is cost effective backup at $1100. Just make sure you are going into it eyes wide open. I enjoy the robust nature of the setup, and the resiliency and paid a lot for it.

 

[vicwill]

First, I'd check to be sure it does not move you from a favorable rate plan where you have now to one much less favorable to the consumer. Electric companies have gotten smart on how to get their money since several years ago people received NEM 1 installs receivign a 1 kWh for 1 kWh credit for power produced to the NEM 3 type rated now that charge the consumer a fixed rate per kWh of panels on the roof whether and buy excess power back at a rate 1/3 rd of what you pay. The NEM 3 makes a payback period almost undoable.

My guess would be several thousand dollars, perhaps $20k. It really depends. I expect it to be less than that rather than more.

My price for a battery installed is $12k per 10 kWh - 15 kWh. There is a lot that goes into a coded install. I'm guessing the panel with circuit breakers will be an additional $5k. This includes cutting the wall out and repairs and an inspected install.

Growing up in Massachusetts and now in Arizona, I'm amazed at how few kWh you use for an all electric house, especially for heat in the winter. In AZ, I estimate my daily AC is 100 kWh. Between 2 ACs, they use 5 kW per hour on average per day in the summer. Up to 120 kWh per day. I just measrured my fridge and it uses 4 kWh per day.

EDIT: Equipment cost is a small cost of the overall install and I would not recommend having an installer put in equipment he is not familiar with and learn on your dime. If you contact EG4 by DM on this board, they will provide you local installers if you choose to go that route.

Thank for your input. National grid in Massachusetts has a one-to-one kilowatt hour exchange. I believe that does not change with installing battery back up. My energy use stated is accurate based on my solar output and my electric bills, I have a very energy efficient home. I also live alone and don’t use a whole lot of electricity, I am very fortunate that way. My house is pretty airtight and I have over 7 tons of blown in dense pack cellulose insulation. My walls are 12 inches thick. My roof is 18 inches. My slab foundation is also surrounded by insulation. It cost more to build initially but is paying dividends now in comfort and energy savings.

 

[vicwill]

Hi vicwill,
Your math is not mathing. You may want to double check what you typed in the post because the numbers are not making sense. You stated that your max use was 1093 kWh for the month, but then the systems you listed individual usage for adds up to 1250 kWh alone, without all of the odds and ends that are not listed.

I have a home battery backup system. The terms cost effective, and home battery backup don't really go together. Not a code compliant setup anyhow. A small generator like my Harbor Freight inverter 8750 is cost effective backup at $1100. Just make sure you are going into it eyes wide open. I enjoy the robust nature of the setup, and the resiliency and paid a lot for it.

Thanks for this input. Up until last February, with my net metering and my solar set up, I hadn’t paid an electric bill for almost 2 years. My total electricity bill from last March to the previous March came to a little over $400. I live alone and don’t use much electricity. My double stud walls are 12 inches thick in my roof is 18 inches thick. I have over 7 tons of blown in dense pack cellulose insulation. I will definitely get total estimates from qualified installers to be able to figure out if the upfront cost is worth it.

 

[vicwill]

I agree on the kWh in the winter. I'm in NC and it's mild here, by my top expense come JAN/FEB is heating. Granted there are much more efficient heat pumps for heating than my unit, but OP are you sure you don't have some gas supplementation?

Granted I have a 3000sq ft house so size matters...but that is impressive.
I can't wait for my heat pump to finally die so I can swap it for a more efficient model.

No gas supplementation. My house is 900 sq ft open concept living/kitchen with my bedrooms and bathroom downstairs and an approximate 400 foot loft upstairs.

 

[Recovering EE]

I added a DIY off-grid system *inside* an existing, permitted grid-tied battery backed-up system. I simply removed about half the house from the old system using a two-pole transfer switch to disconnect an existing sub-panel from the old system.

There is no new utility connection, and all the existing system knows is that half its load is gone. The new system does not export at all, and its GRID input comes from the old system. I used an EG4 6000XP, two EG4 All-Weather WallMount batteries, and 6.4kW of new PV (two strings, east and west-facing)