400 amp main panel recommendations? (Norcal, PG&E)

[summit]

You can put in a higher amperage panel, meter, and main breaker without PG&E upgrading their service, if you aren't actually increasing loads.

actually a really good idea

For PV, my approach is to avoid 120% rule by not backfeeding a breaker panel, instead "load side tap" after main breaker, fans out to sub panels and PV safety switch. I'm using 100A switch, but you would want 200A if something like SolArk.

does this mean PV production is effective curbed ? or battery stored ?

 

[zanydroid]

does this mean PV production is effective curbed ? or battery stored ?

In general? Only if you program it as such. This is not always available.

For this specific case. I believe max inverter output on 15K is 15kW (needs combination of PV and battery output). That works out to 78A with 125% continuous scaling. So there is no need to limit when going back through a 100A switch.

However the 200A switch may still be a good idea because 15k can bypass 200A, so putting it behind a 100A switch and service is not using it to the max

 

[Hedges]

actually a really good idea

does this mean PV production is effective curbed ? or battery stored ?

No, I'm just not backfeeding a 200A or 225A busbar in breaker panel.
The objective is for 100% of PV (15.4kW) to backfeed grid if not used locally.

Rather than, 200A busbar 200A main breaker 40A PV breaker 32A PV = 7680W,
or with 225A busbar and 70A PV breaker, PV = 13,440W

Also, can take in grid power and supply 200A main panel from battery inverter.

Polaris is probably good for 400A or more.

PG&E -->
meter -->
200A main breaker -->
Polaris -->
100A fused safety switch || 200A sub-panel || 100A sub-panel

The safety switch will go to PV aggregator panel (or battery inverter with PV inverters downstream)
Each sub-panel can be fed direct from grid (from Polaris), or can switch interlocked "generator" breaker and be fed from battery inverter.

Normal operation:

Grid feeds 200A panel with larger heating loads.

Grid feeds (or is fed by) 100A safety switch, which feeds battery inverter, backfed with PV. Battery inverter goes through load-shed relay to generator breaker of 100A important loads panel.

Critical loads are directly on PV aggregator panel, always on (so long as battery holds out.)

That's my soon-to-be system. Sunny Boy, Sunny Island for battery backup.

My sister's will be different:
200A panel (center fed, I hope 120% rule has been relaxed)
7.68kW Sunny Boy Smart Energy with 15kW of PV, optional HV battery.
That can only backfeed 7.68kW, but remaining power from PV up to 10kW can go to battery for later backfeed.
Eventual goal is to feed her ADU, and sell power to renters in primary dwelling.

In your case, a 400A panel with 320A breaker could allow huge amount of PV backfeed. 160A of PV breaker?

 

[IcarusPrime]

Thank you for all the replies and sorry for the late reply. Our third child was born last month and of course we found out our entire plumbing system(original 1960s cast iron waste pipes and copper supply lines) needed to be replaced.

I’ve spent the better half of a sleepless month vetting contractors and learning how to design our water system. It’s finally finished and we couldn’t be happier and now i can finally jump back into this thread.

There seems to be a lot of concern about the “need” for a 400 amp panel and service. As I mentioned previously we wanted to future proof our home.

I’m a bit of a noob but from what little I think i know, that 400 amp service could be used up quite quickly. I’ve read tankless electric water heaters draw a ton and given we have three children, i could imagine having 5 EVs in about 16 years, that needed to be charged on a daily basis and yes, simultaneously.

I believe I also mentioned on my original post we planned on going pretty much all electric on everything including our hvac system. I can’t remember if I also mentioned I’m considering installing an electric radiant floor heating system throughout the house.

There’s also the 120% rule issue. Again, im a bit ignorant, but this is also what I was trying to mitigate by having a very large panel/service.

Looks like I need to research/familiarize myself more with the nuances of line side taps and load side interconnections. Thanks to all who pointed out the options.

We, live in the city proper, so there doesn’t seem to be a charge for our upgrade in service from PG&E.

-IP

 

[zanydroid]

The tankless water heaters should be reexamined… tankless gas makes sense to me but tankless water heater forces electrical upgrades on everybody and also wastes high quality form of energy. HPWH are better if you’re going to be heating.

5 EVs… calculate how many miles you expect your family members to drive per day, convert to kWh with like 3.5 mi/kwh factor and add a buffer. Most two car households with two commutes can recover the daily commute overnight on a single 40A EVSE.

Back before automatic EV load management was a thing, people did indeed need 400A service. In 16 years the load management will probably be easy enough to configure to charge each car to a preprogrammed SoC. Or move power between EVs as needed.

 

[IcarusPrime]

I think you’re missing the intent. My intention is to create an electrical system that can facilitate, as much as possible, all of my familiy’s future electric desires at the lowest long term cost.

Why would I use gas for my WH? Home solar in the long run is significantly cheaper than gas. Electric based WHs are typically longer lasting than their gas counterparts, especially when paired with filtration and water softening. Then there’s also the air quality being affected by gas WH.

Another thing I’ve considered is how a hpwh doesn’t work well with a recirculating pump and their ability to produce copious amounts of hot water quickly, is questionable. Our washing machine is working nearly non-stop now with our kids being toddlers, how much more when they’re old enough to be involved in sports and other activities, where they’re going through 3-4 outfits a day?

My wife and I both have 100+ mile daily commutes and 3.5 miles per kwh is typical for a smaller EVs. I don’t necessarily think that all the EVs we’ll be getting will get that kind of mileage. Also, I can imagine our family moving to larger EVs for the added safety and comfort.

Lastly, I’d rather have a larger electrical system than I need than a smaller one and making concessions. I can always find other things to use the extra electricity. I’m sure a few crypto mining rigs would easily deal with any excess we could produce

 

[zanydroid]

There’s also the 120% rule issue. Again, im a bit ignorant, but this is also what I was trying to mitigate by having a very large panel/service.

This is a function of the panel busbar, not the service size.

I have approval to push about 70A of solar back up a 100A service from PG&E

We, live in the city proper, so there doesn’t seem to be a charge for our upgrade in service from PG&E.

OK, given how expensive this house might be overall, sure it’s not a big deal. And putting on real estate instead of engineer hat maybe the 400A service is needed to match the market comparable, and upgrading an underground service later can be extremely expensive and annoying

 

[zanydroid]

Why would I use gas for my WH? Home solar in the long run is significantly cheaper than gas. Electric based WHs are typically longer lasting than their gas counterparts, especially when paired with filtration and water softening. Then there’s also the air quality being affected by gas WH.

The gas point, I don’t think is productive to spend time to explain more, I’ve written it up a few times on other forums.

Won’t you need a massive storage inverter to support electric instant on NEM3? Unless the averaging interval for billing is long enough such that the spike can be made up over time by pushing more back to the utility. I think there is a post here somewhere about the averaging duration.

Another thing I’ve considered is how a hpwh doesn’t work well with a recirculating pump and their ability to produce copious amounts of hot water quickly, is questionable. Our washing machine is working nearly non-stop now with our kids being toddlers, how much more when they’re old enough to be involved in sports and other activities, where they’re going through 3-4 outfits a day?

HPWH should be considered in how much they can bank up slowly between usage.

The storage tank provides an alternative way to bank up the electrical power vs installing more storage.

You have fewer code restrictions in adding more HPWH in parallel than adding equivalent amount of ESS storage (which has several kWh caps). I haven’t mathed out how many you need to support 200A of AC to support the instant hot water heater.

The recirculation pump issue IMO is something you can invest time engineering around to harvest the 3x efficiency gain and power smoothing. Much more elegant than killing it with instant WH. But I can be convinced with calculations comparing the two options.

My wife and I both have 100+ mile daily commutes and 3.5 miles per kwh is typical for a smaller EVs. I don’t necessarily think that all the EVs we’ll be getting will get that kind of mileage. Also, I can imagine our family moving to larger EVs for the added safety and comfort.

3.5 is for a EV6/Ioniq5/model Y size EV, which is what I consider main stream. I guess if you want the next size up it will be lower.

EDIT: OK , did not factor in climate control and poor weather drag for average U.S. climate, it will be definitely below 3.5 for much of the U.S. in the winter.

I’m sure a few crypto mining rigs would easily deal with any excess we could produce

All right, this is just silly to mention crypto with any environmental discussions. I’m out of this thread.

 

[DIYrich]

Another thing I’ve considered is how a hpwh doesn’t work well with a recirculating pump and their ability to produce copious amounts of hot water quickly, is questionable. Our washing machine is working nearly non-stop now with our kids being toddlers, how much more when they’re old enough to be involved in sports and other activities, where they’re going through 3-4 outfits a day?

HPHW uses about 0.4 kW while running in heat pump mode. Assuming incoming water at 50f, and desired temp of 140f, that is 5.85 gallons per hour when the 140f water is blended down to 120f. A 50 gal HPHW heater @140f can deliver about 50 gal blended to 120f. Get two, and you have 100 gal available instantly (for showers), and 11gal/hr recovery (which is enough for laundry) and use about 1 kW continuously, or about 4 amps @ 240v. Plus, it cools the house in the summer.

At best, an instant electric hot water heater is 3412 BTU per kW, and needs power of around 30kW for 5 gpm. A HPHW heater can double or triple that with 1kW. Plus, you would need two EG4 18k PV or Sol-Ark 15k just for that peak need, a third for the rest of the house, and a fourth for ev charging (get home at midnight, cars are charging, AC running during the summer, and you take a shower).

My wife and I both have 100+ mile daily commutes and 3.5 miles per kwh is typical for a smaller EVs. I don’t necessarily think that all the EVs we’ll be getting will get that kind of mileage. Also, I can imagine our family moving to larger EVs for the added safety and comfort.

200 miles at 3.0 kWh per mile is 67 kWh. Charging over 5 hours is 14 kWh per hour, or about 55 amps at 240v. Charging for 8 hours gets you 320 miles, or you can reduce the amps to 35 for 200 miles.

Between HPHW and EV charging, you are looking at 40-60 amps.

The rest of the house should be able to stay within 100 amps overnight, and 150 amps Noon-9pm when not charging.

Using HPHW, you could get by with two 18kpv or 15k inverters.

Getting a load controller could turn off car charging while you have other peak loads (taking a shower). In your base case, you could drop down to 3 inverters, and in the HPHW case, you might be able to get by with one (charge 8 hours overnight, with minimal loads at night).