diy solar

diy solar

Quote feedback please?

glandpuck said:
I'm in So Cal. Looking at your system, roughly speaking the hardware costs are about 16.4K and the remainder is labor, permitting, passing inspection, etc.

As for batteries, a UL listed 40 kW system should cost you no more than 14K plus maybe 2K for installation. This is based on say using 8 Pytes batteries which are UL listed high quality. They can be viewed at: www.pytesusa.com. Plus this forum has many others. www.stackrackbattery.com also sells UL listed indoor and outdoor cabinets for the batteries.
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I did look at Pytes, but they don't publish pricing so I moved on. I landed on the Ruixu from Will's video, and his strong recommendation. The price is excellent.
glandpuck said:
To total this all up, I think about 50K for the system installed with the batteries and either solar panel would be a decent price before the Federal tax credit.

What I don't understand is why you want to spend 50K on a PV system and battery when you have such cheap energy from your utility company? The payback period doesn't seem to make any sense.

Would you invest any money up front knowing that you would need to wait 8-10 years to get a return on your investment?
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It's not 50K, it's 30K after tax credits. I think you're confusing ROI and payback, I get ROI the very next month when my power-bill is lower. Yes, I often make investments with multi-year payoff periods. I estimate 8 years for this system with the current rates, and I expect those rates to go up.
glandpuck said:
An alternative may just be to install a powerwall type system (there are several to choose from) without any solar panels, charge the batteries at night when the rate is cheap and use them during emergencies.
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I would need a substantially larger battery if I were to entirely forgo solar, doubling the size and cost of the battery. I've landed on a large set of affordable batteries, but If it turns out I actually do need to change them to UL9045 ones I will need to downsize them due to cost. Doing both, using solar during the day and arbitraging at night is the best approach.
 
chicagoandy said:
Total Georgia Power consumption in 2023 was 20,447 kwh, using the EV TOU rate. ($.02/kwh overnight, $.25/kwh peak afternoon). Annual spend in 2023 was $2,904, $.142/kwh avg.
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chicagoandy said:
I would need a substantially larger battery if I were to entirely forgo solar, doubling the size and cost of the battery. I've landed on a large set of affordable batteries, but If it turns out I actually do need to change them to UL9045 ones I will need to downsize them due to cost. Doing both, using solar during the day and arbitraging at night is the best approach.
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He does make a good point. If you can buy power for $0.02 and store it for $0.05, that's $0.07 vs. $0.25.

The battery life is expected to be 6000 cycles, 16 years. You would reach break-even at 5 years.

That is only considering cost of a battery like PowerPro, not inverter cost. Question is how many batteries, and cost of inverter, so how much over $0.07 it actually costs per kWh, to supply power you otherwise use during peak times. 1x EG4 18kpv + 1x PowerPro would cost considerably more. Perhaps a powerwall type product with smaller inverter is a better fit.
 
Hedges said:
He does make a good point. If you can buy power for $0.02 and store it for $0.05, that's $0.07 vs. $0.25.

The battery life is expected to be 6000 cycles, 16 years. You would reach break-even at 5 years.

That is only considering cost of a battery like PowerPro, not inverter cost. Question is how many batteries, and cost of inverter, so how much over $0.07 it actually costs per kWh, to supply power you otherwise use during peak times. 1x EG4 18kpv + 1x PowerPro would cost considerably more. Perhaps a powerwall type product with smaller inverter is a better fit.
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In So Cal, how about charge the batts with PV and run the home off PV 18 hours a day. Avoid $0.45 to $1.05 per kW rates and use grid for $0.15 in middle of night if needed. Now that is why California has large scale corporations building out massive battery sub-stations all over the state to charge in the day with PV and provide to the local utility at night.
 
OP says he can buy power from the grid for $0.02/kWh.
Can't make it that cheap with PV. Costs 25% more (DIY) to 5x as much (turnkey) using PV.

He could potentially DIY PV during the day cheaper than storing in a battery. But probably not if loads cycle on and off, need at least a battery buffer.

So I suggest considering just a battery, buy low, use when rates are high.
Grid-tied zero export battery. Completely fail-safe power, because if it goes offline, grid supplies loads like before.
Simply a Powerwall type application. Or Sunny Boy Storage. But the trick is finding most cost effective one.
 
I've updated my post, the overnight rates are not $.02, Georgia Power does hide a number of cost recovery fees, including a large $.06 fuel recovery fee. Admittedly they are still low enough to make a Californian angry. Overnight "all-in" are roughly $.08, and $.32 during the afternoon.

I'm not clear what "solarwall" type product you're recommending. The Tesla SolarWall is both smaller and more expensive than the one I have planned. (Ruixy 52kwh for $12,000 - very tough to beeat on price/capability). But more importantly it won't meet my needs.

Additionally I would still need a large inverter, as getting my 3 3-ton Air-Conditioners mostly off the grid is a key value. So I'd need enough inverting to power 3 ACs, and enough battery to run them, as peak AC is also peak TOU rates. The Tesla solar inverter would not meet those needs.

If I were to drop the PV, I'd still need a Sol-Ark 15k or similar to power the ACs. If I keep the same batteries I'd be hitting the peak utility rates I'm trying to avoid later in the evening. Having the PV means I won't drain the batteries during peak afternoon cooling.

TOU arbitrage is fun, but it doesn't work without solar or even larger batteries because most of the power consumption takes place during peak TOU rates (bad) and peak solar (good).

I am thinking maybe I dial back the PV. Switch to the slightly smaller QCells instead of REC panels, and drop 4 I had added over a sunroom.
 
$0.08 off-peak and $0.32 peak, those were my prices in San Jose 20 years ago when I put in PV (I think tiered as well, not just time of use.)

I mean the functionality of a Tesla PowerWall or SMA Sunny Boy Storage. Not necessarily those brands. What matters is low enough $/kWh of cycle life to make arbitrage between $0.08 and $0.32 worthwhile.

If you do have peak solar and peak TOU at the same time, that is good. Used to be that way for me, and with net metering I could get $0.32 credit, then consume later at $0.08. Around the clock and year round, I figure I got back 1.5 kWh for every 1.0 kWh I produced.

You don't need an inverter able to supply your air conditioner, unless you're trying to run during grid outages, or disconnected from the grid. Just need to supply watts from a grid-interactive inverter, to reduce or eliminate grid draw.

All you need is an AC coupled battery. Or a hybrid inverter with battery.
It charges from grid during off-peak, then exports to the house (but not to the grid; CT at meter avoid that.)
This is called shaving - shave imports by backfeeding from battery. But only during times of peak rates.
(Another forum member had SBS + LG battery for a year and wasn't getting savings, because it was shaving peak power during off-peak rates. Has to be programmed correctly.)

You can charge the battery for $0.08/kWh, so it makes no sense to pay for turnkey PV install; that will cost you $0.10/kWh amortized over 20 years.

Start by considering EG4 18kpv and one or more PowerPro, because we know they are UL listed as ESS. Determine how many batteries needed to supply power during the times rates are higher than $0.08/kWh.

See if any less expensive inverters are UL listed ESS, if that is required. And other brands.

Alternatively, If your power draw is near continuous during peak rates, then GT PV zero export and no batteries could also work.
 
In general NEC does not officially specify specific UL standards in the codes. Instead the relevant standards are usually mentioned in the associated informational notes as guidance for the local AHJ's who ultimately decide what's acceptable.

For example: https://up.codes/viewer/illinois/nfpa-70-2020/chapter/7/special-conditions#706

UL9540 is mentioned as the relevant standard for ESS. Unless you can convince your AHJ you don't have an ESS as NEC defines it then UL9540 compliance is likely required. Best to talk to your local AHJ before purchasing anything.
 
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