60 Amp install for FCSP at $1,500, or 80 amp at $2,200. Is it worth the extra $ ?

[cvalue13]

PS: gotta love it

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[Labs4Lightning]

What wire did you use?

Aluminum from panel to disconnect
Disconnect to charger copper.

saved me more than 500 because of long run, 2 conductors

 

[ryan]

Thanks, 1awg aluminum and 3awg copper? My electrician was planning 2awg aluminum to the transition box but I'm thinking that's a little... aggressive.

Aluminum from panel to disconnect
Disconnect to charger copper.

saved me more than 500 because of long run, 2 conductors

 

[jefro]

I can live on 40A.

 

[PV2EV]

awesome and helpful reply

on the text quoted above, could you hand-hold me one step further in what exact functionality we’re describing there?

perhaps at issue here is not only my lack of ability in the topic in general, but also some quirks about Austin’s electrical grid oddities. Namely, they have a meter both in front and behind the PV, so charge for solar PV even if the grid is down - which is why I have no home battery/inverter installed with my PV currently (because from a cost perspective it’s useless, except to the extent of providing a battery in a blackout that I still get charged for)

So I have 21KW of PV, I have a lightning, but am still not certain of what the HIS $ will buy me in terms of capabilities - seemingly this “grid-tie” mode you mention being something I should understand better

Other than carbon reduction (which was a large part of why I installed it), why would anyone even install PV if you have to pay for your generation?

 

[PV2EV]

When OFF GRID (meaning power failure), all Delta BDI's can deliver 10 kW to your isolated home's electrical system from the truck's battery.

When ON GRID and operating in "grid-tie" mode with solar PV installs, the Delta BDI's have a range of 4 kW through 10 kW. The default model provided by Sunrun is only able to feed in 4 kW. If you have a larger solar PV install and want to use it to offset your grid usage, you'll need a larger inverter. The rest of the components should remain the same.

From a wiring standpoint, there is very little difference as you'll need to have the 10 kW rated backfeed for off-grid mode to work.

Well said, and thanks for clarifying. To explore a bit further: Assuming the 4kW of the default BDI is the max AC output from PV, is it clear that does not happen when the grid is down?

 

[Maquis]

Thanks, 1awg aluminum and 3awg copper? My electrician was planning 2awg aluminum to the transition box but I'm thinking that's a little... aggressive.

If you plan to use the FCSP at full capacity, a 100A circuit is required, so #1 aluminum / #3 copper.

 

[FlasherZ]

on the text quoted above, could you hand-hold me one step further in what exact functionality we’re describing there?

perhaps at issue here is not only my lack of ability in the topic in general, but also some quirks about Austin’s electrical grid oddities. Namely, they have a meter both in front and behind the PV, so charge for solar PV even if the grid is down - which is why I have no home battery/inverter installed with my PV currently (because from a cost perspective it’s useless, except to the extent of providing a battery in a blackout that I still get charged for)

So I have 21KW of PV, I have a lightning, but am still not certain of what the HIS $ will buy me in terms of capabilities - seemingly this “grid-tie” mode you mention being something I should understand better

You don't have batteries on your system, so you are using what they call a "grid tie" system. If your solar PV system is producing more than your instantaneous demand, the power flows out to the grid and furnishes power to your neighbor's homes. Once production ends (clouds, night, etc.), then you draw from the grid.

If you were to attach your solar panels directly to the default Delta BDI (not through your existing inverters), you would only be able to use 4 kW of power from those panels. But since you have 21 kW of panels, you're already far outside the spec for even the largest BDI.

I'm doing my best to try to keep this simple - so here goes... right now, your solar PV inverters shut down when the grid goes away (UL1741 requirement). It's unclear whether or how well others' inverters will work with the microgrid that gets created by the HIS when the grid is down. In theory, your 21 kW solar PV inverter could sync with the microgrid (your home's needs) created by the HIS, and then your solar PV production could support your own demand while the grid is out.

However, this isn't as easy as it sounds - when you're connected to the grid, the demand and supply of the grid is a GIANT buffer that supports the power your system produces or demands. If you're producing 20 kW in your solar PV, and have 20 kW current demand in your home, then everything is peachy keen - but if the sun suddenly goes behind a cloud, dropping your production to 4 kW, what happens? Well, when you're tied to the grid, you just simply start drawing from it to deal with the demand imbalance. But let's say you are operating on the HIS due to a grid failure - your demand is still 20 kW, but your supply is only 14 kW (10 kW from the truck plus the 4 kW from the shaded panels)... and as a result, the voltage begins to droop and can't be maintained. Likewise, if you can't use the grid as a demand buffer and you produce far more than you consume, then voltage gets driven up until the solar PV system shuts down, out of spec. Sorry if this sounds complex. Ultimately, this may mean that you still can't use your 21 kW of solar PV even if you use the truck battery as backup for your home.

I'd probably need a better drawing to understand your situation with Austin. Our co-op requires two meters as well, but my bill comes from the primary meter and the second one is just so they can track how much of my own energy I consumed vs. how much fed the grid. I pay full retail for every kWh that I draw from the grid, but I get credit at wholesale power producer prices for every kWh that I feed the grid when my demand is less than my production.

 

[FlasherZ]

Well said, and thanks for clarifying. To explore a bit further: Assuming the 4kW of the default BDI is the max AC output from PV, is it clear that does not happen when the grid is down?

To me, it is not (at least not yet). In the post above, I describe the difficulty in dealing with solar PV in a single-home microgrid situation. There's little buffer for absorbing production changes from solar (shaded panels, etc.) or demand changes in the home.

I'm wondering if they're purposely keeping the solar PV feed-in low for this reason, to eliminate the challenges posed by big swings of demand and supply in a microgrid situation. That might allow them to keep the attached solar PV panels in microgrid sync and save some battery power from the truck, while not having to worry about big demand swings creating a shutdown situation.

And then, given that it appears to be able to charge the truck's batteries using DC, if your total demand is even less than what you're producing via solar PV, it can redirect it to charge the truck's battery until it's full.

I can see it working either way but don't have definitive answers.

 

[cvalue13]

Other than carbon reduction (which was a large part of why I installed it), why would anyone even install PV if you have to pay for your generation?

to be a bit clearer, there’s a meter “in front” and “behind” of the solar such that a person is “charged” for (- electricity use) - (+ PV generation) at a given rate for each. So, I’m a given month (on average), I pay the electric company almost nothing because I generate (at a good flat rate) nearly as much I use (on tiered rates). and Austin has no rate differential between hours, so no sort of peak-shaving is possible.

The difference being, a mile west of me outside Austin Energy’s fiefdom, someone with PV can draw directly from their PV during the day, and the utility has no visibility or rate (+ or -) for that.

in Austin, the rate for generation is generous enough PV makes total sense for normal use case.

But really whey *I* did it was a matter of not exactly of ROI, but instead (A) hedging against future electricity rates, + (B) from a cash-flow perspective, pre-paying my electric (ie, I make more money now than I might in the future, so why not pay my future self), and (C) all backed by the addition to value in my home in the instance of a sale

more than you asked for, but that’s the pay of land

but more exactly, it’s why I *didnt* pay for a battery installation. Since there’s no peak shaving possible, and since I can’t dir Dr power house without still being charged for it, the ONLY utility of a battery is to provide power when the grid is down (but still be charged for it!)

Which is why the F150L makes particular sense for me (if only as a generator substitute)

 

[cvalue13]

Put a little differently / more simply: Austin Energy treats residential PV as an extension of their own grid. I just happen to have it located in my roof.

 

[FlasherZ]

to be a bit clearer, there’s a meter “in front” and “behind” of the solar such that a person is “charged” for (- electricity use) - (+ PV generation) at a given rate for each. So, I’m a given month (on average), I pay the electric company almost nothing because I generate (at a good flat rate) nearly as much I use (on tiered rates). and Austin has no rate differential between hours, so no sort of peak-shaving is possible.

You can get some "peak shaving" based upon your daily load, though, if there's a difference in credit rate for what you feed the grid vs. retail rate for what you draw from the grid.

For example, last month I drew 5,961 kWh from the grid (in excess of my own production). But during the peak of the day, I exported 218 kWh to the grid (in excess of my own demand). I pay $0.0946 per kWh, but only receive about half that ($0.05 or so) for what I export. If I wanted to maximize things, I would use those 218 kWh to charge the battery during the day, and use up that charge at night, and then I'd save the difference of the retail rate minus the wholesale rate.

Now, you can see that just doesn't make any sense for me, that'd save me a whole whopping $10 or so in a month, and it would take me 25 years to pay for a $3k battery system, if it lasted that long. But for people who have much larger solar PV systems and much smaller demands, it might make a big difference.

 

[FlasherZ]

Put a little differently / more simply: Austin Energy treats residential PV as an extension of their own grid. I just happen to have it located in my roof.

If it's just basic net metering (what you consume from grid minus what you push out to grid), then you're right, no sense in maintaining a battery. But most power companies want to dump net metering because it doesn't reflect the reality of the demand curve they face. In Illinois, only investor-owned utilities are required to do net metering. Municipal and co-op companies can use different rates for what you consume vs. what you provide to the grid. A local town uses a straight 50% of retail for what you feed to the grid, my co-op uses its wholesale power cost for the amount you feed to the grid.

(A funny story, in 2013 my co-op pulled my electronic meter and stuck in an old "whirly" meter, because their electronic meters couldn't measure bidirectionally. So I did get to see my meter spin backwards. Then in 2016, when I hooked up the second vehicle and charged 2 Teslas at 80A each simultaneously, that meter was humming loudly and it might have had enough thrust to lift the house, lol...)

 

[cvalue13]

You can get some "peak shaving" based upon your daily load, though, if there's a difference in credit rate for what you feed the grid vs. retail rate for what you draw from the grid.

If it's just basic net metering, then you're right, no sense in maintaining a battery. But most power companies want to dump net metering because it doesn't reflect the reality of the demand curve they face.

Yes, it’s just basic net metering. Ironic for Austin, and it’s “forward thinking” energy self-image.

there’s apparently a pilot test somewhere in town for a demand-curve based sort of tiered structure, but zero intel on whether or when that might get rolled out

until then, as my PV installer put it “look, I’ll sell you batteries, but they’re worthless in Austin city limits”

 

[PV2EV]

To me, it is not (at least not yet). In the post above, I describe the difficulty in dealing with solar PV in a single-home microgrid situation. There's little buffer for absorbing production changes from solar (shaded panels, etc.) or demand changes in the home.

I'm wondering if they're purposely keeping the solar PV feed-in low for this reason, to eliminate the challenges posed by big swings of demand and supply in a microgrid situation. That might allow them to keep the attached solar PV panels in microgrid sync and save some battery power from the truck, while not having to worry about big demand swings creating a shutdown situation.

And then, given that it appears to be able to charge the truck's batteries using DC, if your total demand is even less than what you're producing via solar PV, it can redirect it to charge the truck's battery until it's full.

I can see it working either way but don't have definitive answers.

So instead of using this massive battery as a buffer for demand, while mostly feeding PV to load (as most battery/PV systems do), they just cut the AC output from PV. Sad if true.

I had read somewhere that HIS charges the battery via PV DC (when grid down), that is a great and efficient workaround to the above problem (no AC output), but strange they did not get both load and battery power by keeping AC on.

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