Generac PwrCell

[Zer0t]

Does anyone have an understand of the pros/cons of PwrCell vs Pw2? Is it true that you can not use PwrCell with micro inverters vs a single Solar Edge inverter? It seems the largest is about 18kW which I've gotten a price for 23k installed. The issue is I keeping coming back to is that 3 PW 2 are about the same price, have more storage and combined will match the peek out put other than starting amps 50 vs 30.

I do appreciate the education I get here and thanks for bearing with all of my questions that are a bit amateurish.

 

[jjrandorin]

Do you mean to say that you can get 40.5kW of storage in a powerwall 2 and the equivalent pricing for the generac product is 18kW, and you are looking for something other than that as a selling point for a PW2?

Provided both products work (which I am sure they do), that seems to be fairly definitive on its own, without much else.

 

[Zer0t]

Do you mean to say that you can get 40.5kW of storage in a powerwall 2 and the equivalent pricing for the generac product is 18kW, and you are looking for something other than that as a selling point for a PW2?

Provided both products work (which I am sure they do), that seems to be fairly definitive on its own, without much else.

No I am being offered Generac PWRCell by an installer because of the long backorder on the PW2. I'd like to get something installed sooner rather than later. Is the Generac a good replacement for the PW2? I know the price / capacity thing easily goes to the PW2 but is that the only thing to measure?

I'm curious about the inverters that are available as well.

 

[jjrandorin]

I dont have a lot of knowledge around the generac product. I see generac as a generator provider who is trying to pivot to battery storage. Most of the comments I have seen here favor the powerwall 2 (unsurprising, because of what forum this is), for this sort of full circle storage system.

As for "is that the only thing to measure", that depends on an individual person. Price, capacity, app information, whether the company will still be around to support the product during its warranty period, what would that support look like, etc... there are plenty of things to consider.

From my perspective, as I mentioned, Generac is a generator company, that happens to offer battery storage. Tesla, on the other hand, is a battery storage company that happens to offer some products that use that storage (like vehicles).

No matter whether tesla survives itself or not, teslas battery technology isnt going anywhere. If they go out of business, some company will buy the technology, its too good for someone not to. Generac is trying to pivot or play both sides of the fence (like ICE vehicle manufacturers who are building EVs using the same platform their ICE vehicles are on).

Teslas problems are not technology, they are communication based problems.

For me, pivoting to a product which costs the same, but provides less than 1/2 the storage just to move a timeline up a few months, on a product you expect to work for 10+ years, is not something I would do. The product has to be comparable, cost / size / performance, and its not comparable from a cost / size perspective, even if it ends up performing the same function.

TL ; DR -- there is a reason there is a several month backlog for powerwalls, and less of a backlog for other battery products, in my opinion, and swapping to something that has less storage for the same price to move installation up a few months, on a product that is supposed to be used AT LEAST 10 years, doesnt make much sense to me.

 

[holeydonut]

Aside from the availability of the stock, I think the biggest differences between the PwrCell and Powerwalls are simply the PwrCell being DC coupled instead of AC coupled. Some folks like this configuration better because it's more efficient to just turn the DC coming from your solar into DC that gets pushed into your battery. All energy coming from solar and from the batteries has to pass through the Generac inverter.

However, this bottleneck through the Generac inverter kind of becomes the downside of Generac systems. Since their largest inverter is capped at 11.4 kW, it tops off at 50A continuous. This simply isn't enough to run a whole home backup since I don't believe these systems are stackable. As such, Generac systems almost always have a critical loads mini-grid of generation sources and backup.

My understanding (although I'll be damned if I could find a local installer who knew what I was talking about) is that the Generac Gateway is smart enough to meter loads upstream of the backup loads panel so the system can be instructed to export energy from the PwrCell upstream and help energize loads with stored clean energy when the utility is operational. But of course it is limited to a 50A max export.

Because of this wonkiness, one licensed/certified whatever Generac local installer I spoke with said he wouldn't install Generac that way since he typically puts in Generac like any other gas generator or critical loads backup. The Generac system would not see the upstream loads nor would it care to do anything except manage the backed up loads.

Another local installer said what I described with upstream sensing was do-able because the Generac system supports the CTs necessary to meter the load. But he also said he's never seen a customer ask for this. As such, I just don't think Generac is as ready for time of use balancing across the entire home.

Contrast that with Tesla Powerwalls where people like @Vines seem to be able to design highly flexible systems with Tesla's systems that provide partial backup along with whole home energy management when the utility is online.

Also, both battery types are lithium LMC so I think from a chemistry standpoint they're similar. But of course people can deliberate who makes better batteries in through the complex manufacturing processes

 

[zƬesla]

Generac bough out Pika out of Portland, Maine for the battery tech. Some of the original Pika investors are local to me and thought well of the people behind the company. Looks like Generac integrated the Pika tech into the PWRCell and it's a competitive product. May be worth reaching out to Pika directly (pika-energy.com) if you're considering the tech.

 

[cali8484]

Does anyone have an understand of the pros/cons of PwrCell vs Pw2? Is it true that you can not use PwrCell with micro inverters vs a single Solar Edge inverter? It seems the largest is about 18kW which I've gotten a price for 23k installed. The issue is I keeping coming back to is that 3 PW 2 are about the same price, have more storage and combined will match the peek out put other than starting amps 50 vs 30.

I do appreciate the education I get here and thanks for bearing with all of my questions that are a bit amateurish.

It's unlikely you will find other home battery systems at lower cost/kWh than Tesla. That's why most people go with PW despite the often poor customer service.

As for PwrCell, since it's DC coupled it will not work with microinverters in typical setup.

 

[pilotSteve]

perhaps consider the 8kWh each LG Chem RESU dc coupled batteries. I have four of them, two SolarEdge inverters and 10KW solar that provides whole home backup and time shifting with my TOU utility. This is a DC-coupled solution. I originally wanted Powerwalls but the long lead time led me to this system . Very pleased with how it works.

 

[holeydonut]

It's unlikely you will find other home battery systems at lower cost/kWh than Tesla. That's why most people go with PW despite the often poor customer service.

As for PwrCell, since it's DC coupled it will not work with microinverters in typical setup.

Right, Generac Pwrcell definitely cannot co-exist with microinverters since it is DC coupled.

Edit, I also think PwrCell does NOT have the "stormwatch" type of thing where it can be grid-charged in advance of a risk event.

 

[Southpasfan]

Does anyone have an understand of the pros/cons of PwrCell vs Pw2? Is it true that you can not use PwrCell with micro inverters vs a single Solar Edge inverter? It seems the largest is about 18kW which I've gotten a price for 23k installed. The issue is I keeping coming back to is that 3 PW 2 are about the same price, have more storage and combined will match the peek out put other than starting amps 50 vs 30.

I do appreciate the education I get here and thanks for bearing with all of my questions that are a bit amateurish.

50 amps is a real hidden problem. Three PWs gets you 90 amps which is enough for whole home back up.

Without whole home back up rate arbitrage is difficult, maybe impossible. You need the automatic use that PWs provide for that, which can be a big part of justifying getting them in the first place.

Same problem with LG chem, which looks to be a good comparison until you realize you can only get a max of 2 (if I read my research correctly.)

 

[holeydonut]

50 amps is a real hidden problem. Three PWs gets you 90 amps which is enough for whole home back up.

Without whole home back up rate arbitrage is difficult, maybe impossible. You need the automatic use that PWs provide for that, which can be a big part of justifying getting them in the first place.

Same problem with LG chem, which looks to be a good comparison until you realize you can only get a max of 2 (if I read my research correctly.)

That 90A number you brought up assumes the 7kW "export size". Is that a thing now? Has the firmware update gone through for anyone to support this yet?

 

[h2ofun]

That 90A number you brought up assumes the 7kW "export size". Is that a thing now? Has the firmware update gone through for anyone to support this yet?

Not that I have seen

 

[miimura]

Generac bough out Pika out of Portland, Maine for the battery tech. Some of the original Pika investors are local to me and thought well of the people behind the company. Looks like Generac integrated the Pika tech into the PWRCell and it's a competitive product. May be worth reaching out to Pika directly (pika-energy.com) if you're considering the tech.

I would characterize it more like Generac bought Pika Energy and took the American engineered and produced technology and ran it through cost reduction with their existing south-east asian supply chain. Pika was using Panasonic battery cells (non cylindrical). Generac has probably changed to Chinese cells, but I have no basis for that assertion other than the inherent cost advantage.

Pika had a technically superior product with high voltage DC bus. However, the high cost of their American made solution did not justify purchase consideration. I actually talked to one of their technical people at Intersolar several years ago. I proposed that they should make a DC-DC interface available so that people could use salvage EV packs with the rest of their system. He said that they were not interested in doing that for business reasons, but my idea was technically sound.

 

[Southpasfan]

Not that I have seen

I have the old PWs, its 30 amps per. Basically, my electrician pointed out that most houses draw about 60 to 70 amps when everything is turned on. Thats why, to my understanding, that its such a big deal to decided between two PWs or three.

 

[holeydonut]

I have the old PWs, its 30 amps per. Basically, my electrician pointed out that most houses draw about 60 to 70 amps when everything is turned on. Thats why, to my understanding, that its such a big deal to decided between two PWs or three.

Yeah I think you're getting tripped up on the breaker size vs the actual capability of the Powerwall 2 (before Elon's Tweet and possible firmware upgrade).

PW2s as we know of them right now can export 5 kW continuous. This is 21A. But the breaker that sits over the top of them is 30A. So your 3 Powerwalls are best thought of as 60A of export size not 90A.

Now if Elon's tweet about export size becomes reality, apparently a Powerwall 2 will have a 7kW "size". This will give you 88A for your three powerwalls. But then technically each PW breaker would need to be 40A and you'd need upsized conductors. So we don't know how this will all play out for existing customers vs new installs that can have their plans accommodate the 7kW.

 

[h2ofun]

Yeah I think you're getting tripped up on the breaker size vs the actual capability of the Powerwall 2 (before Elon's Tweet and possible firmware upgrade).

PW2s as we know of them right now can export 5 kW continuous. This is 21A. But the breaker that sits over the top of them is 30A. So your 3 Powerwalls are best thought of as 60A of export size not 90A.

Now if Elon's tweet about export size becomes reality, apparently a Powerwall 2 will have a 7kW "size". This will give you 88A for your three powerwalls. But then technically each PW breaker would need to be 40A and you'd need upsized conductors. So we don't know how this will all play out for existing customers vs new installs that can have their plans accommodate the 7kW.

The 7kw is not continuous so as Wayne has posted, a 30 amp breaker will handle the surge current for an AC starting. So no needed upsizing of anything.

 

[holeydonut]

The 7kw is not continuous so as Wayne has posted, a 30 amp breaker will handle the surge current for an AC starting. So no needed upsizing of anything.

If it's not 7kW continuous then what good is it? haha Just to start some stubborn air conditioner compressors?

Ok so Southpas will have what is effectively a 62.5A system for the foreseeable future... not 90A.

 

[h2ofun]

If it's not 7kW continuous then what good is it? haha Just to start some stubborn air conditioner compressors?

Ok so Southpas will have what is effectively a 62.5A system for the foreseeable future... not 90A.

Since many have had to get 3 PW's for the surge current to start the AC, yep, that is huge if the person can go to 2 PW's and have the AC work

 

[zƬesla]

I had the whole house on 2 PWs for most of a year with no issues related to house power draw. Loads includes electric dryer and 5 mini split heads with 2 outdoor units.

A third PW was recently installed, however that was due to 2 PWs not handling PV generation.

 

[h2ofun]

I had the whole house on 2 PWs for most of a year with no issues related to house power draw. Loads includes electric dryer and 5 mini split heads with 2 outdoor units.

A third PW was recently installed, however that was due to 2 PWs not handling PV generation.

What did the PW's not handle from PV? I have 15KW on 2 PW's and am seeing no issues