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Residential solar people?

Yes, liquid to air is common. Even liquid to preheat on demand propane water heater.

Check out the radiant floor controllers and such
 
MChat said:
Putting together a plan for my off-grid property.

I rented a house in Phoenix that had a solar hot water heater, even during the winter the water came out so hot it could warp plastic bottles. So I am thinking on using a solar hot water system, with a propane based tankless water heater as a backup, just in case.

But the way the hot water systems work, got me to thinking. The systems I am looking at have a liquid (similar to antifreeze) that gets pumped up to the roof where the mirror/reflector unit heats it up, the hot liquid then comes down and runs through a heat exchanger that heats the water which you use.

What I am thinking is that instead of a liquid-to-liquid heat exchanger, why couldn't a liquid-to-air heat exchanger be used by an HVAC system. Even if it is only to "prewarm" the air so a propane-based heater doesn't require as much propane to heat the home.

My google-fu has failed, does such a system exist? If not, I could probably piece together a system from water heater parts; if I can figure out it is even worth it.
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Of course it does. You're looking for the same basic hardware that would be used for an outdoor wood boiler. You'll likely need a few hundred gallons of storage to get meaningful heat into the air when the blower runs.
 
larboc said:
Of course it does. You're looking for the same basic hardware that would be used for an outdoor wood boiler. You'll likely need a few hundred gallons of storage to get meaningful heat into the air when the blower runs.
Click to expand...
Yeah I'm pretty set on an outdoor boiler but it will require several hundred gallons in decent tanks to handle the pressure from temperature swing to act as the heat battery. Otherwise you end up with funky cycle times.
 
I've been searching and it may have already been covered (search is failing me and I scanned the thread quickly but didn't see anything), but is there an online resource for 12v residential fixtures? E.g. I can buy a 6" recessed light from Home Depot / Lowes that is essentially a 12v LED light w/ a 110vac to 12vdc "converter", why can't I just buy a bunch of 6" recessed 12vdc LED lights without the converter and wire them up directly to a switch? There's got to be a resource for this, but everything I find is the cheap crap you find in an RV.

I guess I could always buy the light from HD/Lowes and cut the converter off, but then I'll have a mess of these converters laying around and will have probably spent more money as a result.
 
MChat said:
I've been searching and it may have already been covered (search is failing me and I scanned the thread quickly but didn't see anything), but is there an online resource for 12v residential fixtures? E.g. I can buy a 6" recessed light from Home Depot / Lowes that is essentially a 12v LED light w/ a 110vac to 12vdc "converter", why can't I just buy a bunch of 6" recessed 12vdc LED lights without the converter and wire them up directly to a switch? There's got to be a resource for this, but everything I find is the cheap crap you find in an RV.

I guess I could always buy the light from HD/Lowes and cut the converter off, but then I'll have a mess of these converters laying around and will have probably spent more money as a result.
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I believe the canless ones step voltage from 120ac to like 4v DC.

I’ve used the Torchstar ones and have been happy. 120v though no solar or anything. I can try to measure the converter box output though.
 
Even stepping down from 12vdc (or 24vdc) to 4vdc has got to be better than going from 12vdc (or 24vdc) through an inverter to 110vac then back down to 4vdc. I have to imagine that there is a good amount of wasted energy in the transformations.
 
Does anyone have experience with higher voltage dc inverters? Have a good amount of batteries that are wired for 2 packs for 120vdc (240vdc per chassis). I can rewire but it seems like it would be more efficient at higher voltage
 
There are some buck-boost topologies that are 95+% efficient.
Not sure on the exact use case though, off grid etc.
 
kf4zht said:
Does anyone have experience with higher voltage dc inverters? Have a good amount of batteries that are wired for 2 packs for 120vdc (240vdc per chassis). I can rewire but it seems like it would be more efficient at higher voltage
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We looked at a bunch of the china variants for powering direct off EV's but my brother never got the balls to pull the trigger.
I wouldn't think you would need to go higher than 36-48 to get the good brands of equipment.
 
MChat said:
I've been searching and it may have already been covered (search is failing me and I scanned the thread quickly but didn't see anything), but is there an online resource for 12v residential fixtures? E.g. I can buy a 6" recessed light from Home Depot / Lowes that is essentially a 12v LED light w/ a 110vac to 12vdc "converter", why can't I just buy a bunch of 6" recessed 12vdc LED lights without the converter and wire them up directly to a switch? There's got to be a resource for this, but everything I find is the cheap crap you find in an RV.

I guess I could always buy the light from HD/Lowes and cut the converter off, but then I'll have a mess of these converters laying around and will have probably spent more money as a result.
Click to expand...
I found Lighting the Future - Rimikon when I was looking for low voltage switches that look like normal household vs toggle switches. They even have 3-way. You have to check the voltage of their lights, it varies.

Look into MR16 LEDs. There are numerous fixtures that started with halogen bulbs. They are smaller though, like 3".
MR16 fixture.jpg
 
77fixer said:
I found Lighting the Future - Rimikon when I was looking for low voltage switches that look like normal household vs toggle switches. They even have 3-way. You have to check the voltage of their lights, it varies.

Look into MR16 LEDs. There are numerous fixtures that started with halogen bulbs. They are smaller though, like 3".
MR16 fixture.jpg
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This is exactly what I was looking for. Thank you!
 
MChat said:
Putting together a plan for my off-grid property.

I rented a house in Phoenix that had a solar hot water heater, even during the winter the water came out so hot it could warp plastic bottles. So I am thinking on using a solar hot water system, with a propane based tankless water heater as a backup, just in case.

But the way the hot water systems work, got me to thinking. The systems I am looking at have a liquid (similar to antifreeze) that gets pumped up to the roof where the mirror/reflector unit heats it up, the hot liquid then comes down and runs through a heat exchanger that heats the water which you use.

What I am thinking is that instead of a liquid-to-liquid heat exchanger, why couldn't a liquid-to-air heat exchanger be used by an HVAC system. Even if it is only to "prewarm" the air so a propane-based heater doesn't require as much propane to heat the home.

My google-fu has failed, does such a system exist? If not, I could probably piece together a system from water heater parts; if I can figure out it is even worth it.
Click to expand...
Mother Earth News 2006 had an article about a hollow wall in a shed, in Bozeman MT, that they used as a solar collector for hot water, which they use to fill a large reservoir and then pipe to the house and a radiant heat system.

There are other articles about doing something similar but they cut a notch at the top and bottom of the wall, the bottom is the air inlet, top is outlet and it circulates - and a simple "hollow wall" with a glass face can be a (daytime) heater.

Obviously, some insulation in the right places is a good thing, and then some things to disable the passive heater when it's dark outside..
 
tsm1mt said:
There are other articles about doing something similar but they cut a notch at the top and bottom of the wall, the bottom is the air inlet, top is outlet and it circulates - and a simple "hollow wall" with a glass face can be a (daytime) heater.
Click to expand...
"Trombe wall" is the term to search for more of that.
 
Where is the latest. I am wondering how much it dropped now that you are under a couple feet of snow. Are the panels melting the snow or are you sweeping them off?
 
brantb said:
Where is the latest. I am wondering how much it dropped now that you are under a couple feet of snow. Are the panels melting the snow or are you sweeping them off?
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My panels have produced - admittedly, very little - even when covered under snow with overcast skies.

Much much better when they're cleared off and the sun is out.

I found that my panels mounted "just" off the roof tend to hold more snow / longer than the ones that are mounted 6" elevated off the roof - it's easier for the wind to blow it off, and when it does melt, there's more places for the snow to go.

I occasionally broom off the "close to the roof" panels because I can - they're on the 10' wall building, but the stand-off panels are more than 16' off the ground, so nature does its thing.

Get a corner cleared off and the sun starts to do its thing and heats the panel up, melts the snow, and sends a big pile of snow down right outside my man door. :)

This is the output of one of my 12kw arrays (8kw east, 4kw west, or vice versa) just for the month of January.

Youc an see it fluctuates from 1.2kwh in a day to almost 20kwh a day.

Code: 
Jan 12, 2023
1.406
Jan 11, 2023
5.018
Jan 10, 2023
1.964
Jan 9, 2023
4.823
Jan 8, 2023
3.880
Jan 7, 2023
3.517
Jan 6, 2023
1.291
Jan 5, 2023
11.364
Jan 4, 2023
19.464
Jan 3, 2023
18.514
Jan 2, 2023
19.245
Jan 1, 2023
11.027
 
Dang, I fell way behind on updating this and I think I missed some inverter readings as well.
Generally, as expected, I had little generation during the winter and used my credits to keep the bill the $25 service fee. Worst month was January where the inverter only made 18kWh. My utility also goofed up the billing and everything got really weird for Dec.-Feb. It's all straightened out now.
As of April 01 I've got 1937kWh of credits built up. We're still getting snow here but it's sporadic and isn't impacting generation too much. The cold temperatures and sunny days are making kWh. Yesterday was 50.6kWh dawn-dusk.

I assumed zero generation for Dec-feb in my models but ended up with 147 in dec, 18 in jan, and ~200kWh in february (I forgot to take a reading for feb., but sent 143kWh back to the utility).

Bottom line is I've got to find a use for my excess generation. I think there was some fine print in the interconnection agreement about not exceeding your demand.
 
larboc said:
Dang, I fell way behind on updating this and I think I missed some inverter readings as well.
Generally, as expected, I had little generation during the winter and used my credits to keep the bill the $25 service fee. Worst month was January where the inverter only made 18kWh. My utility also goofed up the billing and everything got really weird for Dec.-Feb. It's all straightened out now.
As of April 01 I've got 1937kWh of credits built up. We're still getting snow here but it's sporadic and isn't impacting generation too much. The cold temperatures and sunny days are making kWh. Yesterday was 50.6kWh dawn-dusk.

I assumed zero generation for Dec-feb in my models but ended up with 147 in dec, 18 in jan, and ~200kWh in february (I forgot to take a reading for feb., but sent 143kWh back to the utility).

Bottom line is I've got to find a use for my excess generation. I think there was some fine print in the interconnection agreement about not exceeding your demand.
Click to expand...
So you got the water heating covered?

edit: :homer: HPWH LOL
 
larboc said:
Dang, I fell way behind on updating this and I think I missed some inverter readings as well.
Generally, as expected, I had little generation during the winter and used my credits to keep the bill the $25 service fee. Worst month was January where the inverter only made 18kWh. My utility also goofed up the billing and everything got really weird for Dec.-Feb. It's all straightened out now.
As of April 01 I've got 1937kWh of credits built up. We're still getting snow here but it's sporadic and isn't impacting generation too much. The cold temperatures and sunny days are making kWh. Yesterday was 50.6kWh dawn-dusk.

I assumed zero generation for Dec-feb in my models but ended up with 147 in dec, 18 in jan, and ~200kWh in february (I forgot to take a reading for feb., but sent 143kWh back to the utility).

Bottom line is I've got to find a use for my excess generation. I think there was some fine print in the interconnection agreement about not exceeding your demand.
Click to expand...
So what you got for ideas? This is the funnest part of this shit to me the "excess"
 
electric casting furnace (well, pottery kiln with the thermostat swapped out for a meaner one)
 
Your gonna have to get a ev now to use up that excess.:lmao:

Maybe an electric train for moving stuff around the yard.
 
I put a couple victrons in my cabin and like them so far. I dont know if their efficiency is worth the price for my use, but for you they might be.
 
I wish ABQ NM would allow me to pull a permit but they are really being assholes.

So far I've received two quotes for the following systems

10KW Ground based system
Microinverters from Enphase
No batteries
Power on during grid failure
Ability to hook generator up to system
Purchase in cash

Before the 30% back from federal and 10% from state
Positive solar - 54k , 33k after rebates
Ion Solar - 52K, 31k after rebates

I still have two more companies to reach out to in ABQ for quotes. Ones a local company with the second being in CA and NM. But quotes seem high but maybe labor and shit has really gone thru the roof for this stuff.
 
Duc said:
I wish ABQ NM would allow me to pull a permit but they are really being assholes.

So far I've received two quotes for the following systems

10KW Ground based system
Microinverters from Enphase
No batteries
Power on during grid failure
Ability to hook generator up to system
Purchase in cash

Before the 30% back from federal and 10% from state
Positive solar - 54k , 33k after rebates
Ion Solar - 52K, 31k after rebates

I still have two more companies to reach out to in ABQ for quotes. Ones a local company with the second being in CA and NM. But quotes seem high but maybe labor and shit has really gone thru the roof for this stuff.
Click to expand...
Lots of profit in those quotes id say.
 
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