Thoughts on this setup? Also, a SGIP question.

[Kbreezy92]

Hi guys,
I just put in my order last Thursday for 8.16 kW solar panels + 1 powerwall in the Bay Area. I was wondering what people's thoughts were on 1 powerwall vs two powerwalls. I know it will be a partial backup vs a whole home backup and I'm ok with not having the ac tied the backup. But I was also wondering about problems if I over produce during a blackout and capacity issues with just one powerwall vs two powerwalls.

I'm thinking of getting the second powerwall just concerned about if the SGIP rebate and if I will get it. If I'm pretty confident on that I would probably without hesitation get another wall but I would be more comfortable to afford one at the moment.

Some background:
Live in Peninsula with PGE. Need at least 9000 kwh production per year and I fall in between the small and medium size for panels. I charge one model 3 at home twice a week. Also run a Mitsubishi mini split for my a/c with 5 heads (only use 3 currently). Tesla quoted 11,000 production for 8.16 kwh panels. Thanks and let me know your guys thoughts.

 

[jjrandorin]

Hi guys,
I just put in my order last Thursday for 8.16 kW solar panels + 1 powerwall in the Bay Area. I was wondering what people's thoughts were on 1 powerwall vs two powerwalls. I know it will be a partial backup vs a whole home backup and I'm ok with not having the ac tied the backup. But I was also wondering about problems if I over produce during a blackout and capacity issues with just one powerwall vs two powerwalls.

I'm thinking of getting the second powerwall just concerned about if the SGIP rebate and if I will get it. If I'm pretty confident on that I would probably without hesitation get another wall but I would be more comfortable to afford one at the moment.

Some background:
Live in Peninsula with PGE. Need at least 9000 kwh production per year and I fall in between the small and medium size for panels. I charge one model 3 at home twice a week. Also run a Mitsubishi mini split for my a/c with 5 heads (only use 3 currently). Tesla quoted 11,000 production for 8.16 kwh panels. Thanks and let me know your guys thoughts.

If you are going through tesla, plan on NOT getting any SGIP. If you are going through some other installer, they can tell you where they are on the steps or not. There are enough people ahead of you that on tesla's side, they will be far oversubscribed before your turn comes up, so its highly unlikely you get any SGIP if going through tesla.

With that being said, if you are only really looking at price, the price tesla is charging (and not getting the SGIP) is basically the same as most third parties will be charging you WITH sgip factored in.

Meaning, your out of pocket initial spend with most third parties will be higher, then you will have to get that rebate, to bring it in line with what tesla is charging up front, where you almost assuredly will not get any SGIP as they have reached all of their caps (and have a long line of people still waiting).

On the "1 powerwall with 8.16 kWh of solar" question, thats been a hot button here recently for some reason (amount of solar to pair with how many powerwalls). There is discussion in a couple of threads you can look at, but you seem to already understand the basic issue.

There is no hard and fast rule but it depends on your home load and where your panels are, etc etc. FWIW, I believe a "decent rule of thumb" would be 1 PW per 5-6kWh of PV, but it depends on a bunch of factors. If I was getting your system, however, I would get 2 powerwalls... but its very easy for me to spend your money lol.

 

[Kbreezy92]

If you are going through tesla, plan on NOT getting any SGIP. If you are going through some other installer, they can tell you where they are on the steps or not. There are enough people ahead of you that on tesla's side, they will be far oversubscribed before your turn comes up, so its highly unlikely you get any SGIP if going through tesla.

With that being said, if you are only really looking at price, the price tesla is charging (and not getting the SGIP) is basically the same as most third parties will be charging you WITH sgip factored in.

Meaning, your out of pocket initial spend with most third parties will be higher, then you will have to get that rebate, to bring it in line with what tesla is charging up front, where you almost assuredly will not get any SGIP as they have reached all of their caps (and have a long line of people still waiting).

On the "1 powerwall with 8.16 kWh of solar" question, thats been a hot button here recently for some reason (amount of solar to pair with how many powerwalls). There is discussion in a couple of threads you can look at, but you seem to already understand the basic issue.

There is no hard and fast rule but it depends on your home load and where your panels are, etc etc. FWIW, I believe a "decent rule of thumb" would be 1 PW per 5-6kWh of PV, but it depends on a bunch of factors. If I was getting your system, however, I would get 2 powerwalls... but its very easy for me to spend your money lol.

Even if step 6 is going to open up soon? I was told to just order now and applications will be submitted for step 6. So your saying at this point step 6 and 7 will be given to the huge backlog that Tesla has on powerwall installs and there wouldn't be enough for people who apply now?

 

[Vines]

Of course they told you to order soon, thats their job. Applications will be sent does not mean you will get any money, especially in the 1-2 Powerwall category. Do not plan on getting SGIP from Tesla as their waiting list is huge.

A few smaller installers still have money in the "Small Scale" SGIP Funds bucket, but I am sure those are running out quickly for everyone. For instance the company I work for has run out of those small scale funds for a year or more. All we have left is funds for 3 or more Powerwalls.

Still as pointed out above, Tesla pricing is so cheap that it will be similar in the end between with SGIP and a 3rp party installer, vs no SGIP and Tesla. 3rd parties will give you more attention for that extra money up front so the value may be there for you.

There's tons of threads on the topic of overproduction and frequency shifting, but if you plan on running any AC for more than a couple hours, get the 2nd Powerwall imo.

 

[jboy210]

To answer the question about overproduction, you should be fine. The Gateway needs to have a sink for that excess solar power or shutdown the solar production. Once the Powerwall fills AND the grid is down there is no energy sink so the Gateway will raise the AC frequency on the inverters taking them off line, which will kill solar production. Then when your usage drains the Powerwall down, the gateway will detect the space in the Powerwall and bring solar back online. This cycle repeats.


The only caveat I am aware of is what happens after you deplete the Powerwall in the evening/night. I n theory you should start store power in the power wall sometime in the next day. But it is not clear in my mind how that works with a depleted power wall in an extended outage Does the gateway wait until solar has recharged the Powerwalls to a certain threshold before bringing the house online so there is a buffer? Or does the house come online immediately? Or ...

 

[Vines]

Like any lithium ion battery you really don't want to let it go to 0% charge and the GW doesn't either. In a cold start morning situation, you may also have the temperature working against you, as the batteries will not take 5 kW charge when dead cold. More like 1.5 kW or 3kW maybe between the internal heater and the charger, especially in freezing climates. Those in freezing climates shouldn't really have the PW outside the building envelope.

The Gateway leaves a reserve in the Powerwalls so they can create a 60-66 hZ micro grid each morning, that the PV will recognize and respond to accordingly.

 

[jjrandorin]

Even if step 6 is going to open up soon? I was told to just order now and applications will be submitted for step 6. So your saying at this point step 6 and 7 will be given to the huge backlog that Tesla has on powerwall installs and there wouldn't be enough for people who apply now?

Yeah, "even though step 6 and 7 are going to open up soon"

I got mine installed in january of this year, before "step 6 and 7" even existed, and I "hope" that tesla will get to my application in the queue before they hit their cap with one of those. There is virtually zero chance that you will get SGIP from tesla at all, so dont plan on it. They only submit for 1-2 powerwall sized jobs themselves, per their information, and they have enough of those done already that its likely that people like me who installed in january of this year wont get it.

its highly highly highly unlikely you get any SGIP money going through tesla. Certainly do NOT calculate it into your "total cost" through tesla for example.

If I knew in nov of last year what I know right now, I would have gotten 3 powerwalls through a third party instead of 2 through tesla, to get into the "large scale" budget and have the price be not much more than I paid (net) to tesla for 2 powerwalls. I want a third one as it is, but will figure that out at some other point.

 

[Kbreezy92]

Yeah, "even though step 6 and 7 are going to open up soon"

I got mine installed in january of this year, before "step 6 and 7" even existed, and I "hope" that tesla will get to my application in the queue before they hit their cap with one of those. There is virtually zero chance that you will get SGIP from tesla at all, so dont plan on it. They only submit for 1-2 powerwall sized jobs themselves, per their information, and they have enough of those done already that its likely that people like me who installed in january of this year wont get it.

its highly highly highly unlikely you get any SGIP money going through tesla. Certainly do NOT calculate it into your "total cost" through tesla for example.

If I knew in nov of last year what I know right now, I would have gotten 3 powerwalls through a third party instead of 2 through tesla, to get into the "large scale" budget and have the price be not much more than I paid (net) to tesla for 2 powerwalls. I want a third one as it is, but will figure that out at some other point.

Thanks for your input. I didn't know about the problems with SGIP so I figured I would ask. Looks like I'll be just getting one powerwall for now. I just figured it would be easier to just do a whole house backup now instead of getting a partial and then later on decide on getting another powerwall and reconfigure it to whole house backup.

 

[jjrandorin]

Thanks for your input. I didn't know about the problems with SGIP so I figured I would ask. Looks like I'll be just getting one powerwall for now. I just figured it would be easier to just do a whole house backup now instead of getting a partial and then later on decide on getting another powerwall and reconfigure it to whole house backup.

it would be easier (and cheaper) to do it now. it will likely cost you the same you pay for 1 now to add the second one later (or even more than it cost to do one now).

if you ever think you will want a second one, you should either do both now, or not do either, and save up, and do both later. They will need to re wire your partial backup if you add a second one later, so it will be the same price as you pay now (no savings at all for having an existing powerwall, to go from 1 to 2).

Conversely, doing 2 now (at least through tesla) the installation cost is basically waved, saving you 2.5k.

 

[Vines]

Thanks for your input. I didn't know about the problems with SGIP so I figured I would ask. Looks like I'll be just getting one powerwall for now. I just figured it would be easier to just do a whole house backup now instead of getting a partial and then later on decide on getting another powerwall and reconfigure it to whole house backup.

Good thing to remember ESS Fire codes are changing July 1 next year. These may limit the locations that Powerwalls may be installed inside as well as adding onerous monitoring requirements.. We are just fighting this battle with CALSSA and its unknown how future code enforcement will go. If you are counting on adding more Powerwalls later with a stacking kit that is up in the air still. Rules are only getting tighter, especially in the Bay Area.

Many new rules seem to push the Powerwalls outside, which works ok in Bay Area climate and likely not near as well else where.

Depending on your jurisdiction (Currently Santa Clara County unincorporated areas, Los Gatos, Oakland, Campbell, SF), mounting inside you may have to deal with additional city requirements like garage heat detectors monitored by your alarm system, and impact protection in the form of bollards. If you are installing outside on an exterior wall away from any doors and windows, likely you still will be able to do this same location in a few years.

Hopefully Tesla will finish UL 9540a testing successfully with the new standard and at least we can use the stacking kit again and mount closer than 36" from each other in those strict jurisdictions.

Also since smaller installers have SGIP funds still for 3 or more Powerwalls you will find 3 Powerwalls and whole home backup competitive with 2 from Tesla and partial home backup, when you factor in the value of whole home backup. PGE will give you back something like $3k per Powerwall for 3 of them, so that's something to consider. If your home is on well water and in Fire danger area you may get 100% paid for (though that program is currently closed, it may reopen)

Your Main service Panel determines a lot about the ease of doing a whole home backup with the main service panel you have vs needing a MSP upgrade for an additional $5k. If you post a picture of your Main service panel sticker, and the inside of the panel showing the breakers I can tell you more about what you can do with current equipment.

 

[Kbreezy92]

Good thing to remember ESS Fire codes are changing July 1 next year. These may limit the locations that Powerwalls may be installed inside as well as adding onerous monitoring requirements.. We are just fighting this battle with CALSSA and its unknown how future code enforcement will go. If you are counting on adding more Powerwalls later with a stacking kit that is up in the air still. Rules are only getting tighter, especially in the Bay Area.

Many new rules seem to push the Powerwalls outside, which works ok in Bay Area climate and likely not near as well else where.

Depending on your jurisdiction (Currently Santa Clara County unincorporated areas, Los Gatos, Oakland, Campbell, SF), mounting inside you may have to deal with additional city requirements like garage heat detectors monitored by your alarm system, and impact protection in the form of bollards. If you are installing outside on an exterior wall away from any doors and windows, likely you still will be able to do this same location in a few years.

Hopefully Tesla will finish UL 9540a testing successfully with the new standard and at least we can use the stacking kit again and mount closer than 36" from each other in those strict jurisdictions.

Also since smaller installers have SGIP funds still for 3 or more Powerwalls you will find 3 Powerwalls and whole home backup competitive with 2 from Tesla and partial home backup, when you factor in the value of whole home backup. PGE will give you back something like $3k per Powerwall for 3 of them, so that's something to consider. If your home is on well water and in Fire danger area you may get 100% paid for (though that program is currently closed, it may reopen)

Your Main service Panel determines a lot about the ease of doing a whole home backup with the main service panel you have vs needing a MSP upgrade for an additional $5k. If you post a picture of your Main service panel sticker, and the inside of the panel showing the breakers I can tell you more about what you can do with current equipment.

Tesla didn't say I needed a panel upgrade. I already sent them pictures and such of my break panel, a/c, etc. Not sure if they change their minds after coming for a site visit tomorrow. Attached are the pictures.

 

[Kbreezy92]

it would be easier (and cheaper) to do it now. it will likely cost you the same you pay for 1 now to add the second one later (or even more than it cost to do one now).

if you ever think you will want a second one, you should either do both now, or not do either, and save up, and do both later. They will need to re wire your partial backup if you add a second one later, so it will be the same price as you pay now (no savings at all for having an existing powerwall, to go from 1 to 2).

Conversely, doing 2 now (at least through tesla) the installation cost is basically waved, saving you 2.5k.

Thanks for your reply. Yeah I did the calculations for that. I just reread some of the previous comments. It looks like if one powerwall would suffice for me with an 8.16 kW system then I'd likely never need to add an additional powerwall since I don't really care if my ac is backed up during outages. I just need backup for my fridge and other small 120v appliances. It would be nice to have my ac backed up too but I don't think it's worth it for the extra cost right now. So yeah, I definitely have alot of thinking to do between zero, one, or two powerwalls.

 

[JPP]

Note that if you qualify for the SGIP Equity Resiliency program there might be a shorter path to funds. If not, basically you will likely never see any PG&E SGIP funds.

 

[Vines]

Tesla appears right, also you can convert that panel to whole home backup easily enough, if you wanted.

However it looks like you are pretty well set with 1 Powerwall if you have those needs. 3 Powerwalls, even at the price of 2 with SGIP funds is a large chunk of money.

 

[Kbreezy92]

Note that if you qualify for the SGIP Equity Resiliency program there might be a shorter path to funds. If not, basically you will likely never see any PG&E SGIP funds.

Yeah just checked the map. The area I'm in San Mateo isn't covered.