Wise to Downgrade Service?

[adamlive]

Hello, I'm about to pull the trigger on an EG4 12000XP which will use grid backup. This has an absolute max pass-thru of 100amp. Our house has an existing 150amp main disconnect at the meter, from the 1960s. I have pretty extensive consumption logs for several years, and we don't really ever exceed 7kw for the whole house... we run pretty efficient. We already have a heat pump for the whole house, plus a mini split. Even if we add an EV charger eventually, we're well under 24kw (100 amp) service.

I had Greenlancer draw everything up and they added a 200amp disconnect and 3/0 copper from meter to inverter. That's the closest common standard to 150amp but I feel like I'm spending quite a bit of money on oversized hardware & wire when I'm limited to 100amp. I also don't have room for a big 'ol DU324RB without moving the meter a few inches. I could easily save $1k switching to a 100amp disconnect and using 1/0 copper, and everything physically fits easily. (And since everything downstream of the inverter is 1/0, it'd be nice to just get a spool and use it everywhere.)

Is that short-sighted? These days "everyone's" recommending 200amp service, so we're taking a half-step backwards, but I don't feel like our usage demands it. Yes, we could eventually parallel another 12000XP or something but again - nothing about our usage suggests we'll need it.

Will an inspector freak out about a 150-amp panel behind a 100-amp fused disconnect? If that's going to be a bigger can of worms, I won't rock the boat, but it seems impractical to me right now.

 

[wpns]

Sounds good to me

 

[SouthernSolar]

It’s likely code requires the 200 amp service

 

[adamlive]

It’s likely code requires the 200 amp service

Can you be more specific or at least something that can point me that way? Obviously this would be a final answer if so.

Still would feel silly to feed a 100amp maximum load with a 200amp service.

 

[dougbert]

Hello,

hello and great questions

I'm about to pull the trigger on an EG4 12000XP which will use grid backup. This has an absolute max pass-thru of 100amp. Our house has an existing 150amp main disconnect at the meter, from the 1960s.

are you thinking of a direct feeder from 150amp breaker to inverter OR is there room to drop a 150amp main panel between the two?
if I had the room I would do that with a 100amp breaker them feeding the inverter. that provides the 100 amp limit, but also gives you a grid panel for future whatever

but I could not find a panel for under $150

I have pretty extensive consumption logs for several years, and we don't really ever exceed 7kw for the whole house... we run pretty efficient. We already have a heat pump for the whole house, plus a mini split. Even if we add an EV charger eventually, we're well under 24kw (100 amp) service.

I had Greenlancer draw everything up and they added a 200amp disconnect and 3/0 copper from meter to inverter. That's the closest common standard to 150amp but I feel like I'm spending quite a bit of money on oversized hardware & wire when I'm limited to 100amp. I also don't have room for a big 'ol DU324RB without moving the meter a few inches. I could easily save $1k switching to a 100amp disconnect and using 1/0 copper, and everything physically fits easily. (And since everything downstream of the inverter is 1/0, it'd be nice to just get a spool and use it everywhere.)

NEC states the minimum grid service is 100 amp for a residence, so you are good there

in relation to your main panel, where are you putting the 12000xp?

Is that short-sighted?

I don't think so, other than that breaker is near or past it functional life span

These days "everyone's" recommending 200amp service, so we're taking a half-step backwards, but I don't feel like our usage demands it. Yes, we could eventually parallel another 12000XP or something but again - nothing about our usage suggests we'll need it.

for a 2 12000xp setup, you will need an AC INPUT combiner panel and an AC OUTPUT combiner panel so you should plan on space for that
see the 12000xp wiring diagram here the wiring

Will an inspector freak out about a 150-amp panel behind a 100-amp fused disconnect? If that's going to be a bigger can of worms, I won't rock the boat, but it seems impractical to me right now.

probably not


I would try to keep the 150 amp service (updating the breaker at least) and add an intermediate panel between main breaker and inverter if you can find the space/room

I have a 125 amp service and am upgrading to a new 150 amp service entrance, as I installed the 125 amp one 30 years ago

 

[SouthernSolar]

Can you be more specific or at least something that can point me that way? Obviously this would be a final answer if so.

Still would feel silly to feed a 100amp maximum load with a 200amp service.

Another member has answered. I knew there was a minimum service size. I was thinking it was 200, but I am wrong or may vary by location.

 

[adamlive]

I appreciate everyone's feedback, I've gone back/forth but I think I'm gonna settle on a compromise as hinted above: 200amp disconnect and 3/0 as suggested to the Inverter (which is closer to the meter than the house panel anyway) and then do a sub-panel next to the Inverter and land the EV charger there. Not only is that the most efficient wiring distance, but I can just run 1/0 to the house panel since the constant loads there are well under 100 amp without the EV. Granted, I'm still limited to 100 amp @ 240v grand total, but if I ever had to add a parallel inverter or an external ATS bypass, it would be a much easier job... even if I don't foresee that in the near future.

Theoretically that would also make it easy to use the Smart Load port, but I'm already planning to use the EV charger itself to vary charge speed rather than binary on/off. My plan is to take total solar input, subtract what the house needs, and send like 75% to the EV (if plugged in) until full before focusing on battery rack. Then I at least avoid some of the conversion penalties in going Solar -> DC -> Battery -> DC -> AC -> DC -> EV!

 

[Lavarock7]

Is there any possibility that you will sell the place between now and forever and that the new owners will need to swap out to use a higher capacity, maybe getting rid of solar or doing electric vehicle charging or run crypto mining?

I say that because in the 74 years in my memory my parents moved perhaps 10 times and each time my Mother swore 'This is the LAST time I am going through another move!'

 

[adamlive]

Is there any possibility that you will sell the place between now and forever

Good question. I'm sure everyone says this but the odds are low. It's been in our family since it was built 60+ years ago, and my wife and I put a lot of money and sweat equity into it, to make it perfect for us. I own a business that is pretty firmly established in the community. So it is awfully unlikely we'd leave town, and even less likely we'd pursue a different house. That's one of our main arguments for getting solar up North here... we're okay with a decade-long ROI.

 

[dougbert]

can you share pictures of your project - love to see others' work?

 

[Haysdb]

200A service is the standard in the US. My service in Thailand is 15(45), 15A (at 230v) continuous with 45A peak. It hardly matters because I don't import much power from the grid with 12.65 kW of solar and battery, but it does limit me somewhat on how much power I can export. But I digress. 200A? Holy Shit. At 220v that's...44 kilowatts?

 

[dougbert]

200A service is the standard in the US. My service in Thailand is 15(45), 15A (at 230v) continuous with 45A peak. It hardly matters because I don't import much power from the grid with 12.65 kW of solar and battery, but it does limit me somewhat on how much power I can export. But I digress. 200A? Holy Shit. At 220v that's...44 kilowatts?

yes, and since our voltage standard is 240v, it is 48 kilowatts, but continuous load operation, the system should top draw at 160 amps - 38400 watts

 

[Haysdb]

yes, and since our voltage standard is 240v, it is 48 kilowatts, but continuous load operation, the system should top draw at 160 amps - 38400 watts

We use 1200 kwh some months and the absolute peak power I have ever seen is around 7 kW. I think the biggest service available in Thailand (single phase) is 45A.

 

[adamlive]

200A service is the standard in the US. My service in Thailand is 15(45), 15A (at 230v) continuous with 45A peak. It hardly matters because I don't import much power from the grid with 12.65 kW of solar and battery, but it does limit me somewhat on how much power I can export. But I digress. 200A? Holy Shit. At 220v that's...44 kilowatts?

It's a hot topic but I think a lot comes down to future-proofing and the cost of labor vs materials. When building a new house, it's not a huge difference in cost to wire for 200a instead of 100a... but upgrading a house later is significantly more expensive.

Still, at the risk of being attacked, I think some people get 200a service out of irrational fear and never actually come close to exceeding a 100a.

At the same time, the mentality of "always go bigger" can be pretty ridiculous. I've got a pretty decent-sized home, 4 bedrooms, two large living areas. Most of the house is on a heat pump with the upstairs on a separate mini split. Our stove and clothes dryer are gas. And it just so happens we also peak about 7kW and around 1400kWh most months. Like you, I could technically fit on a 45-amp service, but with not much wiggle room.

Now, if I added an electric water heater, two EV chargers, an electric stove, and electric clothes dryer - AND ran them all at the same time - I could be around 150 amps (with vehicles using a huge chunk of that.) Using the 125% rule for margin of error that's darn-near 200 amp service. But again that's designing for the worst-case situation AND adding a large margin. That's how 200 amp becomes "recommended". It IS a lot of power, but in reality my house spends a lot of time under 2kW and never exceeds 8kW and we're probably the biggest in the neighborhood.

 

[MTM98290]

We added a 27kw Instant hot water heater last winter. It takes 3 40A 240V breakers to power it. The power company had to install another transformer much closer as the original was 1/4 Mile away. The heater was very weak and the house would drop to 110V when the heater came on. With the new transformer and higher voltage lines to it we now have a solid 118V-120V no matter what. 130°F water is now endless which is great. 100A service wouldn't run the unit. It doesn't save electricity at all, but endless hot water is worth it for us.

I say all this to illustrate that you or future family members may find a need for more than the 100A provides, especially if you may ever get a battery powered vehicle. Over sizing is always better than undersizing when it comes to wiring in my view.

 

[Daddy Tanuki]

I was amazed at how low the systems were/are in japan when i first started renting a house. the minimum was a 20 amp service. no kidding but back then most people got by without a/c so the only real draws would have been lighting. the house in yokosuka had 60 amp service which we bumped up to 100 amp service that was needed for the grid tied PV system.

 

[Haysdb]

We added a 27kw Instant hot water heater last winter. It takes 3 40A 240V breakers to power it. The power company had to install another transformer much closer as the original was 1/4 Mile away. The heater was very weak and the house would drop to 110V when the heater came on. With the new transformer and higher voltage lines to it we now have a solid 118V-120V no matter what. 130°F water is now endless which is great. 100A service wouldn't run the unit. It doesn't save electricity at all, but endless hot water is worth it for us.

I say all this to illustrate that you or future family members may find a need for more than the 100A provides, especially if you may ever get a battery powered vehicle. Over sizing is always better than undersizing when it comes to wiring in my view.

Thailand uses on-demand electric water heaters almost exclusively but they install one per shower rather than a whole-house unit. We installed a "boiler" in our house and it uses around 2800 watts for 20 minutes twice a day.

 

[MTM98290]

Thailand uses on-demand electric water heaters almost exclusively but they install one per shower rather than a whole-house unit. We installed a "boiler" in our house and it uses around 2800 watts for 20 minutes twice a day.

That sounds fairly efficient. Having warmer groundwater temperature allows for a small sytem to work well. Is this an electric boiler?

 

[Haysdb]

That sounds fairly efficient. Having warmer groundwater temperature allows for a smell sytem to work well. Is this an electric boiler?

I hadn't thought about the groundwater temperature. One of the interesting aspects of Thailand is that EVERY house has a big water tank and a water pump. The municipal water only runs twice a day for some period of time, like maybe an hour or two hours. During this time the tanks all get filled. The pump then provides the water pressure.

Our water heater is a horizontal tank with an electric heating element. It's small by western standards but it's only used for showers. There isn't hot water running anywhere else. The washing machine doesn't even get hot water.

 

[MTM98290]

I hadn't thought about the groundwater temperature. One of the interesting aspects of Thailand is that EVERY house has a big water tank and a water pump. The municipal water only runs twice a day for some period of time, like maybe an hour or two hours. During this time the tanks all get filled. The pump then provides the water pressure.

Our water heater is a horizontal tank with an electric heating element. It's small by western standards but it's only used for showers. There isn't hot water running anywhere else. The washing machine doesn't even get hot water.

That sounds pretty efficient for sure. Are the tanks pressurized or do you run your own pumps to pressurize your own system?

Our groundwater is 48-55°F or 9-13°C so it takes a lot to warm it up. Our municipal water comes from a mountain lake 20 miles away.

 

[Haysdb]

That sounds pretty efficient for sure. Are the tanks pressurized or do you run your own pumps to pressurize your own system?

Our groundwater is 48-55°F or 9-13°C so it takes a lot to warm it up. Our municipal water comes from a mountain lake 20 miles away.

There is a pump.

 

[DIYrich]

Hello, I'm about to pull the trigger on an EG4 12000XP which will use grid backup.

If you are going to spend a lot on the inverter/panels/battery, if I were you, I would spend the additional $2,400 and get the 18kpv. The 18kpv is better at using the grid to supplement power, whereas the 12000xp is all-or-nothing with the grid.

 

[Haysdb]

If you are going to spend a lot on the inverter/panels/battery, if I were you, I would spend the additional $2,400 and get the 18kpv. The 18kpv is better at using the grid to supplement power, whereas the 12000xp is all-or-nothing with the grid.

Explain. My Deye inverter uses only as much grid power as required to satisfy the load after PV and available battery power is used. The 12000xp does not?

I limit battery discharge power via a Home Assistant automation, so there are times when I'm importing a few hundred watts from the grid to supplement battery power. I'm trying to keep as much battery power as possible in reserve while simultaneously trying to use all of it every night.