Heat Pump VS Solar Heating

Pool_Medic

In The Industry
Apr 1, 2018
1,554
Bangor Maine
If your panels are aligned properly in relation to the sun they definitely will match or exceed a heat pump. The caveat is solar panels require sun, full sun, whereas a heat pump generates heat in ambient temps. So a couldnt 80 degree day will realize minimal heat rise with your panels but a heat pump can easily get your pool to 90 degrees.
 

panic_button

Bronze Supporter
Jun 23, 2019
336
Emerald Coast Florida
Pool Size
21000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When we lived in Vegas (Summerlin) we had a gas heater and solar. I can tell you that the solar panel were a pain. The first 2 years of the warranty we has service several times a year for leaks. When they removed the roof panels after 7 years the terra cotta roof had damage, stains and fading due to the minor leaks and techs walking on the roof. In the long run the savings from the solar was offset by the roof repairs.
 

jacobg

Bronze Supporter
Mar 31, 2021
21
Lodi, CA
Pool Size
22000
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
From what I have found, FAFCO panels are somewhere between 1000-2000 BTU/sqft per DAY. I don't know what a "day" is but I was running my pump from 10am-6pm. So assuming 1500 BTU/sqft/day, that's 576k BTU/day which is 72k BTU/hour. The heat pump maxes out at 140k BTU/hour. It's on a curve though, obviously and not as simplistic. Thus far I'd say performance is similar with less drop off in the afternoon/evening as the sun sets with the heat pump. The solar panels heat output drops quickly in the afternoon.
 

grey1988

Well-known member
Nov 14, 2017
50
Las Vegas/NV
From what I have found, FAFCO panels are somewhere between 1000-2000 BTU/sqft per DAY. I don't know what a "day" is but I was running my pump from 10am-6pm. So assuming 1500 BTU/sqft/day, that's 576k BTU/day which is 72k BTU/hour. The heat pump maxes out at 140k BTU/hour. It's on a curve though, obviously and not as simplistic. Thus far I'd say performance is similar with less drop off in the afternoon/evening as the sun sets with the heat pump. The solar panels heat output drops quickly in the afternoon.
It's so hard to know what's what. I wish i really could tell apples to apples. When you explain it in that way, the Heat Pump might be the better option. Using the word day for the 1000-2000 btu is so vague
 

jacobg

Bronze Supporter
Mar 31, 2021
21
Lodi, CA
Pool Size
22000
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It's so hard to know what's what. I wish i really could tell apples to apples. When you explain it in that way, the Heat Pump might be the better option. Using the word day for the 1000-2000 btu is so vague
Performance wise, I had no problems with my solar thermal. It worked great, I had to turn them off in the middle of the summer otherwise the pool would get too hot. They worked great. Then they sprung a leak. And are worthless for the 6 months we don't swim. With solar PV now I'll generate electricity during those months. I'm not thrilled that I have to pay to heat my pool now but it is what it is. And like I said, I've been trying to find the silver lining. The heat pump runs from 10-11:30 bringing pool from 77 to 81F. Then I shut it off. At 2pm yesterday I raised temps to 83 and it hit it at 6pm. Put it back to 81 today and again it was off at 11:30am.
 

House2021

Member
May 24, 2021
7
Woodland Hills, Ca
I live in the inland part of LA and just got the raypak 8450 heat pump. Humidity is around 30% here and max temp yesterday was 78. I turned on the heat pump at 8am and ran it until 8pm for my 35000 gallon pool.

When I turned it on the pool was 69 degrees and by 8pm it was 78. So it definitely does work. However this thing is an energy hog. During this time it used about 80 kw/h electricity. I have a 9kw solar pv which generated 47kw/h yesterday on a sunny day with no clouds but it was not close to enough to run this thing.

Perhaps it will only need to run a few hours a day to maintain the temp and then the solar pv will be enough. Also I’m thinking of scheduling it to run only from 12pm to 4pm which is when it is the hottest and hopefully it will be most efficient. Running for 4 hours should use about 25kw/h which my PV solar can cover. Not sure if it will be able to maintain 82 degrees without a cover
 

House2021

Member
May 24, 2021
7
Woodland Hills, Ca
Here are the last three days according to Screenconnect. The air temp sensor is in direct sunlight I believe - ambient air temp peaked at 88F the first day and is supposed to be 90F today. I have no cover and get quite a bit of heat loss at night, clearly.

First day no heat pump, no solar, no cover.
Second day, heat pump ran from 10am-6pm.
Third day is right now.

Without a cover this is going to be expensive. I haven’t measured running amps from the 8450 but I figure it’s in the 30A range. My electricity averages $0.31/kWh due to high usage and so this thing will cost me $2.10/hour to run - $17/day. Once I get the Solar PV installed and get a cover this will all make more sense. It was nice getting warmer water at dusk last night - solar thermal could not provide that. It’s still cheaper than gas if you consider here gas is $2/therm and 400k btu heater is 4 therms/hour. That’s two hours of gas heat (650k btu in pool) compared to 8 hours heat pump (800k btu in pool). And that’s assuming my 140k btu heat pump is deregulated down to 100k due to low humidity which I think is WAY conservative and probably wrong. And once the PV goes up I can dump excess generation into the pool instead of being reimbursed the absurd generation credit of $.05/kWh.
how's the heat pump working out for you since then? How many hours a day do you have to run it to maintain the temperature?

For me the rates are as follows:

electricity first 500 kw/h $0.17 per kw and $0.21 after that. With my solar PV I'm hoping to never be in tier 2.

gas is first 50 therms $1.11 per therm and then $1.55 after. With gas heater it will quickly use up 50 therms so mostly will be in the 2nd tier especially considering a gas stove and gas water heater using some of it.
 

jacobg

Bronze Supporter
Mar 31, 2021
21
Lodi, CA
Pool Size
22000
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
how's the heat pump working out for you since then? How many hours a day do you have to run it to maintain the temperature?

For me the rates are as follows:

electricity first 500 kw/h $0.17 per kw and $0.21 after that. With my solar PV I'm hoping to never be in tier 2.

gas is first 50 therms $1.11 per therm and then $1.55 after. With gas heater it will quickly use up 50 therms so mostly will be in the 2nd tier especially considering a gas stove and gas water heater using some of it.
So far so good although I don't have usage or cost numbers yet and don't have electric bill with usage. I can say that it has been heating pool from overnight losses to 80F in about 2-3 hours. We've had a lot of cold temps this past week and wind which all contribute to the heat loss. I'm going with a 22kW array and hoping, like you, I stay in Tier 1 usage for my municipality, which is $0.15/kWh for the first 800 or so. Then it jumps to $0.33/kWh for everything after that.
 

House2021

Member
May 24, 2021
7
Woodland Hills, Ca
So far so good although I don't have usage or cost numbers yet and don't have electric bill with usage. I can say that it has been heating pool from overnight losses to 80F in about 2-3 hours. We've had a lot of cold temps this past week and wind which all contribute to the heat loss. I'm going with a 22kW array and hoping, like you, I stay in Tier 1 usage for my municipality, which is $0.15/kWh for the first 800 or so. Then it jumps to $0.33/kWh for everything after that.

wow 22kw PV that is huge, must cost over 40k. I wonder how long it would take to use up $40,000 worth of therms by using a gas heater.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread