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Can I add more solar with PG&E?

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
Tips for the hybrid water heater. I installed one last year when I switched my nat gas appliances to electric. Be prepared for noise when it's running in efficiency mode (heat pump mode). Also consider ducting air to and from the water heater. I didn't move the water heater: the hybrid is where the gas one was. That means in the laundry room near the master bedroom. It's loud, but it's in a closet within the laundry room and I walled the closet with thick sound absorbing foam (the outer layer has the angled surface like a recording studio). That works great for reducing the noise and has the water heater near the main use -- the master bathroom -- so there's less heat loss through transport. By ducting to and from the attic I increased the throughput greatly. For most of the year I have hot air in the attic from hot Alabama weather fed into the intake to provide ample heat for the water heater to push onto the water. I vent it back to the attic to have a zero effect on air pressure in the house. I tried exporting it to the living quarters but it made a really cold zone in an otherwise controlled temp house.

As far as solar goes, the hybrid water heater is awesome. My inverter can do 9 kW continuous power. So when I have appliances running simultaneously, the hybrid water heater is rarely a factor is pushing my total load beyond 9 kW (forcing my solar inverter to pull from the grid). The same by the way with my variable speed heat pump. Even in the Alabama summer it rarely goes into full mode and pulls 4 kW because it constantly runs in the summer (keeping the house cool continuously without having to play catchup every 15 minutes or so).

I would have to use ducting because the closest is only 30x30 with exterior door. I thought about having seasonal duct switching but the reality is ducting from the hot attic in the summer will be more efficient than intake and exhaust ducting inside which I'd only do in the summer anyways. Even in the winter, the attic gets quite warm during the day as long as the sun is shining.

I was going to install the Rheem until I found out that their cost reduced Gen 5 which replaced their built-like-a-tank Gen 4 is about 65 to 70 dbm vs the Gen 4 which maxes out at 49 dbm. They finally removed the noise spec on the Gen 5 because it was wrong. You can barely hear the Gen 4 with the compressor on maximum while the Gen 5 is often claimed to be heard through the entire house. Ducting for sure reduces a lot of the noise but much of the noise is vibration that translates through the floor.

If can't find a suitable option equivalent to the Rheem Gen 4, I'll just go straight electric for a few years. The Gen 4 also had the 8" ducting collars built in while the Gen 5 requires you purchase a separate, quite expensive, duct adapter kit made out of plastic that you screw into the water heater casing. The thing that REALLY sucks about the duct adapters is that you lose about 4" of side clearance so where the Gen 4 was an easy mount my my 30x30 water closet, the Gen 5 would require specialized offset duct which will severely limit flow. I'm not even sure it would be suitable. That said, if I don't do seasonal ducting and just duct from the attic, I wouldn't need the side duct, just the top.
 

h2ofun

Active Member
Aug 11, 2020
3,702
893
auburn, ca
Tips for the hybrid water heater. I installed one last year when I switched my nat gas appliances to electric. Be prepared for noise when it's running in efficiency mode (heat pump mode). Also consider ducting air to and from the water heater. I didn't move the water heater: the hybrid is where the gas one was. That means in the laundry room near the master bedroom. It's loud, but it's in a closet within the laundry room and I walled the closet with thick sound absorbing foam (the outer layer has the angled surface like a recording studio). That works great for reducing the noise and has the water heater near the main use -- the master bathroom -- so there's less heat loss through transport. By ducting to and from the attic I increased the throughput greatly. For most of the year I have hot air in the attic from hot Alabama weather fed into the intake to provide ample heat for the water heater to push onto the water. I vent it back to the attic to have a zero effect on air pressure in the house. I tried exporting it to the living quarters but it made a really cold zone in an otherwise controlled temp house.

As far as solar goes, the hybrid water heater is awesome. My inverter can do 9 kW continuous power. So when I have appliances running simultaneously, the hybrid water heater is rarely a factor is pushing my total load beyond 9 kW (forcing my solar inverter to pull from the grid). The same by the way with my variable speed heat pump. Even in the Alabama summer it rarely goes into full mode and pulls 4 kW because it constantly runs in the summer (keeping the house cool continuously without having to play catchup every 15 minutes or so).
For me, rather than deal with cost and other issues I read about with a hybrid water heater, I am looking at just using standard parts. First I have my solar hot water with like a 80 gallon tank. Then maybe connecting this so a standard electric water heater. Then connecting this to my gas water heater. This seems it would cover all the cases from the best solar in the summer to the least in the winter. Quiet. Cheap, backup options. Any reason this is a bad idea?
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
For me, rather than deal with cost and other issues I read about with a hybrid water heater, I am looking at just using standard parts. First I have my solar hot water with like a 80 gallon tank. Then maybe connecting this so a standard electric water heater. Then connecting this to my gas water heater. This seems it would cover all the cases from the best solar in the summer to the least in the winter. Quiet. Cheap, backup options. Any reason this is a bad idea?

Probably just cost. A well designed reliable solar hot water heating system costs way more than a hybrid water heater + the solar panels to run them.
 

h2ofun

Active Member
Aug 11, 2020
3,702
893
auburn, ca
Probably just cost. A well designed reliable solar hot water heating system costs way more than a hybrid water heater + the solar panels to run them.
Yep, solar hot water is not cheap, and if I knew then what I now know, I would not have done! But now that I already have it, and a gas water heater, trying to save these and add one more piece to make it better
 
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Reactions: sorka
Yep, solar hot water is not cheap, and if I knew then what I now know, I would not have done! But now that I already have it, and a gas water heater, trying to save these and add one more piece to make it better
I looked hard to find a solar hot water solution too, but current regulations in California require a glycol loop (indirect heating), which means two tanks.
Rheem has a combined indirect with gas backup, but it's not low enough emissions to be usable in Southern California.
The cost ended up being 2-3 times the cost of the heatpump water heater I installed, if I could even get it.
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
I looked hard to find a solar hot water solution too, but current regulations in California require a glycol loop (indirect heating), which means two tanks.
Rheem has a combined indirect with gas backup, but it's not low enough emissions to be usable in Southern California.
The cost ended up being 2-3 times the cost of the heatpump water heater I installed, if I could even get it.

This is exactly what I found as well when doing this research last year.
 
Glad I saw this post as I just today signed the contract to install a 9.6kW solar system on my house. Sounds like there’s a number of you that are quite familiar with the PG&E+solar+EV arrangement. My question is what tariff you are on? At present with no solar, I am on EV-2, but my installer says we have to be on TOU-C or D. I’ve been reading the different tariffs and I haven’t seen anything that says I cannot stay on EV-2 but would REALLY appreciate any input on what folks are on. TIA
 

miimura

Well-Known Member
Aug 21, 2013
7,319
7,304
Los Altos, CA
Glad I saw this post as I just today signed the contract to install a 9.6kW solar system on my house. Sounds like there’s a number of you that are quite familiar with the PG&E+solar+EV arrangement. My question is what tariff you are on? At present with no solar, I am on EV-2, but my installer says we have to be on TOU-C or D. I’ve been reading the different tariffs and I haven’t seen anything that says I cannot stay on EV-2 but would REALLY appreciate any input on what folks are on. TIA
You can stay on EV2 if you want to. If you've already been enduring the high price during Peak hours, then with solar you will be fine.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,271
2,659
East Bay NorCal
Unless you completely disconnect from the grid, you will be supporting fossil fuels because they are a necessary component of 24/7 electricity on the grid.


We talked about this in the NEM 3.0 thread... basically a normal home in California would have an exceptionally difficult time fully defecting from the grid. But the intent of many home owners is to at least attempt to offset their own annualized consumption with solar generation. While this imperfect solution may still be subsidizing fossil fuels, it's still a better outcome than just saying "fuggedaboutit" and doing nothing.
 

sorka

Well-Known Member
Feb 28, 2015
9,518
7,825
Merced, CA
Unless you completely disconnect from the grid, you will be supporting fossil fuels because they are a necessary component of 24/7 electricity on the grid.

But I'll be supporting fossil fuels less. As soon as I get more solar, I'll also be switching to self consumption mode. My grid usage will decrease 90%. I will eventually defect from the grid altogether if the proposed NEM 3.0 rules survive and are voted in anywhere near the form they are in. The day that my grandfather period expires and they try to charge me $8 / kw, I will disconnect entirely and buy a backup generator for that week or so in the winter when sun and powerwalls don't quite get me through.
 
But I'll be supporting fossil fuels less. As soon as I get more solar, I'll also be switching to self consumption mode. My grid usage will decrease 90%. I will eventually defect from the grid altogether if the proposed NEM 3.0 rules survive and are voted in anywhere near the form they are in. The day that my grandfather period expires and they try to charge me $8 / kw, I will disconnect entirely and buy a backup generator for that week or so in the winter when sun and powerwalls don't quite get me through.
Sounds like you will have a hard time paying the $128/month for that 16kw system under NEM 3.

You know that backup generator that you are going to run in the winter will not be powered from sunshine.
 
I would have to use ducting because the closest is only 30x30 with exterior door. I thought about having seasonal duct switching but the reality is ducting from the hot attic in the summer will be more efficient than intake and exhaust ducting inside which I'd only do in the summer anyways. Even in the winter, the attic gets quite warm during the day as long as the sun is shining.

I was going to install the Rheem until I found out that their cost reduced Gen 5 which replaced their built-like-a-tank Gen 4 is about 65 to 70 dbm vs the Gen 4 which maxes out at 49 dbm. They finally removed the noise spec on the Gen 5 because it was wrong. You can barely hear the Gen 4 with the compressor on maximum while the Gen 5 is often claimed to be heard through the entire house. Ducting for sure reduces a lot of the noise but much of the noise is vibration that translates through the floor.

If can't find a suitable option equivalent to the Rheem Gen 4, I'll just go straight electric for a few years. The Gen 4 also had the 8" ducting collars built in while the Gen 5 requires you purchase a separate, quite expensive, duct adapter kit made out of plastic that you screw into the water heater casing. The thing that REALLY sucks about the duct adapters is that you lose about 4" of side clearance so where the Gen 4 was an easy mount my my 30x30 water closet, the Gen 5 would require specialized offset duct which will severely limit flow. I'm not even sure it would be suitable. That said, if I don't do seasonal ducting and just duct from the attic, I wouldn't need the side duct, just the top.

I likely have the gen 5, it's 72 dBM right at the top when the compressor is running. water heater is in the garage and I can hear it making a constant sharp sound in the living room after showering. fortunately the compressor doesn't run the whole day so it's ok. but I am looking to get some sound dampening foam from amazon that will hopefully help.
 
I likely have the gen 5, it's 72 dBM right at the top when the compressor is running. water heater is in the garage and I can hear it making a constant sharp sound in the living room after showering. fortunately the compressor doesn't run the whole day so it's ok. but I am looking to get some sound dampening foam from amazon that will hopefully help.
I will be interested to hear what works for you. (;)) The high noise levels is the prime reason why I haven't bought one. For those folks with interior water heaters 72db is just off the charts loud as far as I am concerned.

All the best,

BG
 

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