At what price does LFP storage make it possible to go off-grid?

[NPhil]

Not hidden compartments: hidden releases for your visible batteries slung under the frame!

I don't intend for the batteries to be visible from below. My concept includes smoothing the bottom of the vehicle, perhaps with Coroplast, perhaps sheet-metal, or other such, in some combination, for aerodynamics. I guess I will start with the area where the battery trays fit, and the catalytic converter (not necessarily in that order). I should say that I'm aware that I will have to design the cover over the converter and exhaust system area in a way which doesn't trap too much heat.

You have given me an idea- I could construct the panel which is the bottom of the batteries in a way which appears to be secured from below with screws into the frame rails, when it is in fact secured elsewhere, from inside the van. The screws visible from below would just spin, but not do anything (except, perhaps, trigger an alarm, and perhaps other things (all designed to never cause bodily injury or death, of course).

 

[12VoltInstalls]

The screws visible from below would just spin, but not do anything (except, perhaps, trigger an alarm, and perhaps other things

Now you’re on my page!
Just do ‘other’ places with similar appearance fasteners (functional or not) so it doesn’t stand out

 

[svetz]

These guys predict lithium storage will hit $50/kWh in 2030 for new cells, and that second-life cells (80% of original capacity) will still be good for ESS and "refurbished" batteries (breaking packs down and retaining useful cells) at s $20/kWh.

As the grand-father clause of HB741 lasts for 10 years, those LFP price reductions will be very welcome. Assuming it even passes (I don't even know what it's for. Except for fixed cost recovery, the bits in part 3 (below) are already on my bill).

The net metering may include fixed charges, including 64 base facilities charges, electric grid access fees, or monthly minimum bills, to help ensure that the public utility recovers the fixed costs of serving customers who engage in net metering and that the general body of public utility ratepayers do not subsidize customer-owned or leased generation.

 

[svetz]

Back-of-Envelope vs. Spreadsheet​ So how close was the math in the OP for the symmetric case compared to the spreadsheet? 15¢/kWh, ... insolation of 5... 50 kWh/d ... 10kW array, 20 yr battery life ... 3d Autonomy ... $431 /kWh for battery 20 year payback Off by about 2x in the image to the right. And the spreadsheet is still a rough calculation too.

What about the more reasonable case where the batteries only last 10 years and there's a 2d reserve?
Looks like the price needs to be under $186/kWh. Pity most of us have asymmetric usage.

In an asymmetric example assuming the cost of electricity is 7¢/kWh and a flat $75 grid connect fee with no net-metering ESS needs to drop to $83.20 /kWh for it to be a good investment.



But the number varies widely on you your inputs. For example, above the system used summer insolation - if had used winter it would have been a lot less.

 

[wattmatters]

Some light comic relief ($Aussie):



Even then I don't think 30kW of PV would be enough. And the costs to house 250kWh of battery storage, let alone the electrical infrastructure required, is going to be a LOT of money. A$300/kWh is cheap. That's small DIY stuff. The going rate for a code compliant system would be >A$500/kWh.

LOL.
The grid is a bargain.

 

[huestifer]

In California, they have the Self-Generation Incentive Program (SGIP). SGIP provides a dollar per kilowatt ($/kW) rebate for the energy storage installed. So, they'd want to add that in if they want to participate (might be reasons not to).

I think New York, Massachusetts, and Vermont have deals too, but Maryland is one of the only, if not the only, states in the country currently offering a storage-specific tax credit for its residents. The tax credit covers 30% of the cost of your storage system, up to $5,000 for residential batteries.

Hawaii has some pretty good rebates for storage. It is 35% of the total system cost including batteries and labor. But it is capped at $2500 / 5KW of panels. So it cuts it down quite a bit. But if you can DIY a system on the cheap the tax credit percentage increases the cheaper the system is.

 

[upnorthandpersonal]

Ooops....

 

[eXodus]

Some light comic relief ($Aussie):

View attachment 82084

Even then I don't think 30kW of PV would be enough. And the costs to house 250kWh of battery storage, let alone the electrical infrastructure required, is going to be a LOT of money. A$300/kWh is cheap. That's small DIY stuff. The going rate for a code compliant system would be >A$500/kWh.

LOL.
The grid is a bargain.

looks like a Florida Home Power Usage. But there power is half the price.
You are probably better of to invest into better insulation and a inverter A/C unit first.

 

[svetz]

...Even then I don't think 30kW of PV would be enough... going rate ... >A$500/kWh.

If in Australia, under Solar, your $/W installed might be high (note it's per W, not kW), and your insolation values look to be reversed.

... the costs to house 250kWh of battery storage, let alone the electrical infrastructure required, is going to be a LOT of money. A$300/kWh is cheap. ...The grid is a bargain.

The grid is a bargain at $300/kWh for batteries and your 15¢ to 18¢/kWh grid fee.
But the real question is, at what price would ESS need to fall to in order to make it a "good" deal for your situation?

 

[svetz]

Ooops.... View attachment 82099 If you'd dig your panels out in winter and reflect a little sunlight onto them, your winter insolation wouldn't be zero. ;-)

 

[wattmatters]

looks like a Florida Home Power Usage. But there power is half the price.

I don't actually pay that much and costs are are in Australian $.

Those figures are what grid power would've cost me if I didn't have my 11kW grid tied solar PV system.

Actual annual bills are ~A$1,200. The grid tied PV system saves us circa $3k/year.

To remove the next $400-500/year of electricity bills would require a doubling of that investment to add storage. Not worth it. Grid power is just cheaper (1/3rd the cost) than the throughput cost of a battery.

To remove the final $700-800/year of bills would require spending another $100k+. Definitely not worth it.

You are probably better of to invest into better insulation and a inverter A/C unit first.

It's also consumption for two dwellings / three buildings. Five split system reverse cycle aircons units (one a ducted system) across the three buildings. They are our space heaters as well as coolers. I upgraded some insulation recently and have reduced average daily consumption by 20kWh/day over the past six years through a range of efficiency measures.

I have more to do on the demand side though - it's an ongoing process.

 

[wattmatters]

But the question is, what prices would batteries need to fall to in order to make it a good deal for your situation?

The battery price would have to be significantly negative. That's because the costs associated with building enough production and storage capacity would be very large. For instance it would require constructing a dedicated building just for housing power supply infrastructure plus field based arrays.

 

[minerva]

Some light comic relief ($Aussie):

View attachment 82084

Even then I don't think 30kW of PV would be enough. And the costs to house 250kWh of battery storage, let alone the electrical infrastructure required, is going to be a LOT of money. A$300/kWh is cheap. That's small DIY stuff. The going rate for a code compliant system would be >A$500/kWh.

LOL.
The grid is a bargain.

Your calculations impliy average consumption of 10kW every hour?

 

[wattmatters]

Your calculations impliy average consumption of 10kW every hour?

Where?

I made no calculations, just inputted values.

Note the total consumption of 12,983kWh/year = average power of 1.482kW, not 10kW.

 

[svetz]

The battery price would have to be significantly negative. ... it would require constructing a dedicated building ...

That's a good observation! That was my complaint about LTOs, but I never actually did the math.

Wikipedia says the energy density of LFP is around 325 Wh/l. So, for the 250 kWh of storage that's 250,000 Wh/325 Wh/l = 7200 l, or 7.2 m³ (about 255 ft³). Let's see, a small car is about 6' x 14', So that' the footprint of a small car stacked 4' high (not including space between to get to the cells)?

Solid-state is expected to be around 900 w/l, so that would be 250,000 / 900 = 278 iters or 10 ft³.

 

[wattmatters]

The battery price would have to be significantly negative. That's because the costs associated with building enough production and storage capacity would be very large. For instance it would require constructing a dedicated building just for housing power supply infrastructure plus field based arrays.

Let me put it another way. Our home is unsuitable for taking off grid.

It would need to be bulldozed and rebuilt specifically to operate as an off-grid home. Or we'd need to move elsewhere.

Being off-grid requires a significantly different energy consumption approach and that's not a transition many existing grid supplied homes are suitable for.

looks like a Florida Home Power Usage

Our absolute latitude is about the same as northern Florida.

 

[upnorthandpersonal]

Let me put it another way. Our home is unsuitable for taking off grid.

It would need to be bulldozed and rebuilt specifically to operate as an off-grid home. Or we'd need to move elsewhere.

Being off-grid requires a significantly different energy consumption approach and that's not a transition many existing grid supplied homes are suitable for.


Our absolute latitude is about the same as northern Florida.

Exactly right - remember, the first rule: conservation is cheaper than generation.

If I would have built a typical modern house here in Finland like you would normally, you'd run a heatpump for your heating needs. Doing this with solar is impossible, since there is no sun in winter when you need it the most. The cost of solar panels to even get a few kWh/day in December with solar would be hundreds of thousands of Euro. Solar irradiance in December where I'm at sits at something like 0.05 kWh/m^2/day. Therefor, taking an existing building like this off-grid is impossible.

 

[minerva]

Where?

I made no calculations, just inputted values.

Note the total consumption of 12,983kWh/year = average power of 1.482kW, not 10kW.

The battery cost calls for a total of about 500kWh (2*247) to cover 2 days worth of consumption. For an average of 1.5 kW an hour, you would need 48*1.5= 72 kWh. THat's 72*$300=$21,600. A big difference unless I am missing something.

 

[svetz]

Version 1.3​

Added the volume calculation as shown below. If you enter a $/m³ value it'll add it into the total cost.


Updated: added some comments to those cells to explain it a bit more.

 

[svetz]

The battery cost calls for a total of about 500kWh (2*247) to cover 2 days worth of consumption. For an average of 1.5 kW an hour, you would need 48*1.5= 72 kWh. THat's 72*$300=$21,600. A big difference unless I am missing something.

From his inputs that 247 kWh is two day's autonomy.

From the utility bills the biggest 1-day usage is 99.8 and the maximum two consecutive days is 181.8 (see post#220 for more on that, it's a bit handwavium to catch outliers when it's okay for the generator to run).

The formula for kWh needed is =Max(E3:E14)/2*B19/B20/0.8, which in englishish is the maximum two-day usage divided by two, multiplied by the days reserve, divided by the inverter efficiency, divided by 0.8 (at the end of life the batteries are assumed to be at 80% capacity, so you need more battery starting out).