Question on Tesla Powerwall with Enphase solar panels and cost...

[itsallaboutme]

I have a 7.29 kW system I was thinking about getting a battery to add to my solar panels. My main thing is I want a zero bill all year round. And to be able to use without worrying. This summer the July bill was $88 for electricity. If in the winter it will produce less and my consumption matches the production than I assume I will be getting a bill? But the thing is for July it never showed I used the grid in the Enphase app. The only thing I can think of is that at night when the AC(central air) was on it was using from the grid. (I did see some credit from what I remember 200 minus 800 used I am not sure but the difference made it $88 bill). Is it worth getting a battery? If so from anyones experience is the power wall the choice or stick with Enphase? On YouTube everyone seems biased (salesman) Forgot to mention I have 2 Tesla's that I charge at home. Also have two chargers and 200amp Thanks

 

[jjrandorin]

Unless you are on a time of use plan, with high rates, and a LARGE difference between peak and off peak charges, you are not going to make the math work to buy a powerwall (or any other battery) to "save costs".


You are not using the batteries to charge your car (because in your case you have 150kWh of battery in your cars, and a powerwall is 13.5kW of storage, its like using a AAA battery to charge a bank of 16 D batteries or something, in your case).

If you are dealing with numbers like "$88 dollar electric bill", and a battery install costs roughly $14,000, you are not making that back in any appreciable time. You have to have some value on protection from power outages etc. If you dont, it doesnt make sense from a straight financial situation unless you have a large time of use price delta like I said (and are ok with that still taking several years payback).

 

[itsallaboutme]

Unless you are on a time of use plan, with high rates, and a LARGE difference between peak and off peak charges, you are not going to make the math work to buy a powerwall (or any other battery) to "save costs".


You are not using the batteries to charge your car (because in your case you have 150kWh of battery in your cars, and a powerwall is 13.5kW of storage, its like using a AAA battery to charge a bank of 16 D batteries or something, in your case).

If you are dealing with numbers like "$88 dollar electric bill", and a battery install costs roughly $14,000, you are not making that back in any appreciable time. You have to have some value on protection from power outages etc. If you dont, it doesnt make sense from a straight financial situation unless you have a large time of use price delta like I said (and are ok with that still taking several years payback).

Okay got it. I am still figuring out the solar thing lol. Hasn't been 6 months. Thanks

 

[jjrandorin]

Okay got it. I am still figuring out the solar thing lol. Hasn't been 6 months. Thanks

No problem.

FWIW, just because it may not pencil out (so to speak) doesnt mean they cant be viable. If you put some value on having power during a power outage from your solar system (as it wont run right now when there is a power outage), there is value there.

A lot of people dont realize that if you are in a power outage, and its sunny out, their solar will not power their home unless they have battery storage (there are a couple of products that make that possible, but anyone who had bought those specific products and requested that setup would know it).

One of the most frustrating situations I can remember is being in a power outage, it being sunny outside, and having all my food spoil even though I had solar on my roof that would definitely have provided power and not quite understanding "why" it didnt.

 

[itsallaboutme]

No problem.

FWIW, just because it may not pencil out (so to speak) doesnt mean they cant be viable. If you put some value on having power during a power outage from your solar system (as it wont run right now when there is a power outage), there is value there.

A lot of people dont realize that if you are in a power outage, and its sunny out, their solar will not power their home unless they have battery storage (there are a couple of products that make that possible, but anyone who had bought those specific products and requested that setup would know it).

One of the most frustrating situations I can remember is being in a power outage, it being sunny outside, and having all my food spoil even though I had solar on my roof that would definitely have provided power and not quite understanding "why" it didnt.

I don't really experience power outages. Maybe 5-6 in the 7 years I've been here. They did not last longer than an hour.

 

[holeydonut]

Just to make sure the context of this thread makes sense…

@itsallaboutme is in NJ, so the ROI of adding storage makes little sense.

However, the same isn’t true for say California homeowners adding solar and energy storage under NEM 3. A 10 kWh battery installed alongside the solar means 10 kWh per day can be banked instead of sent to the PoCo at $0.05.

The price differential could easily be $0.30 per kWh if that energy from the batteries is used at peak time. $0.30 per kWh * 10 kWh per day * 365 days is about $1,100 of savings per annum.

The new NEM 3 rules basically force anyone who wants a reasonable ROI with solar to add batteries… the batteries are where that homeowner recoup their investment. Solar by itself makes no economic sense any more. Just in time for the new construction rules requiring solar on rooftops to kick in lolol.

 

[dhrivnak]

I have a 7.29 kW system I was thinking about getting a battery to add to my solar panels. My main thing is I want a zero bill all year round. And to be able to use without worrying. This summer the July bill was $88 for electricity. If in the winter it will produce less and my consumption matches the production than I assume I will be getting a bill? But the thing is for July it never showed I used the grid in the Enphase app. The only thing I can think of is that at night when the AC(central air) was on it was using from the grid. (I did see some credit from what I remember 200 minus 800 used I am not sure but the difference made it $88 bill). Is it worth getting a battery? If so from anyones experience is the power wall the choice or stick with Enphase? On YouTube everyone seems biased (salesman) Forgot to mention I have 2 Tesla's that I charge at home. Also have two chargers and 200amp Thanks

If I am understanding your note you produced (exported) an extra 200kWh and then imported 800kWh during the summer when production is typically at a maximum. So it looks like your solar is too small. I assume you have net metering and if so there is 0 ROI for a battery. I can still help in a grid down situation but it will not reduce your bill.