Heat Exchange or Solar Electric?

[mgill]

Key question - should I remove my heat exchange panels that heat the pool and install solar panels that generate electricity? Will I be ahead if I do so? Details below.

We bought our house 15 years ago and the pool was already installed. The previous owner installed heat exchange panels on the roof, and the panels are inline with the pool water system. The panels are approaching 20 years old. My pool components are listed in my sig but key to this conversation is that I am still using a 2hp single speed pump on a standard timer. Ive also recently replaced the heater - its now a new Raypak 400k BTU unit.

We live in an area where electricity is expensive. Its a tiered system with the first tier being $0.18 per KWh, ramping up to tier 3 which is $0.38 a KWh. About 60% of my current electricity usage is in tier 3. Got our utility bill yesterday, it was $600 for the month. $114 of that is for natural gas, the rest is the electricity.

I have two things to do in the next six months. First get a variable speed pump. Dont need to debate that here - I realize that will bring savings.

Secondly Im considering installing solar panels for electricity. However to make that work optimally it means pulling down the heat exchange panels for the pool. Ive included a snip of my house from google maps below. You can see the exchange panels on the roof (bottom of picture) - that is an Eastern facing plane which is the primary roof the solar guys want. Otherwise I wont get near the efficiently of the solar panels spread across the other roof surfaces.

So, will I be better off with just a variable speed pump and hope it pumps to the 2nd story roof and suck up the electricity bills or go full solar, replace the pump and use a bit more gas from our new heater?

Comments please! Thanks.

 

[gwegan]

I would go with solar electric and then add back as many solar pool panels as possible

 

[pooldv]

A variable speed pump can certainly pump to second floor solar. A 3 hp Intellifo 011055 can do it easily. I think you might be surprised by the savings you will get from a VS pump, they are very efficient. Your current pump likely uses 2000-2500 watts. I run my Intellifo at 1100 rpm for skimming filtering, making chlorine with the SWG and solar standby. It uses 150 watts at 1100 rpm. My Solartouch ramps the pump to 1950 rpm for solar and it uses 550 watts when solar is running. Mine is on a single story building.

If you are running the pump 12 hours a day, 4 hours on standby and 8 hours with solar on it would look like this.
12×2000=24000/1000=24kWh×30 days = 720 kWh per month × $0.38 = $274 per month
4×150=600 + 8×550=4400 5000/1000=5kWh×30 days = 150 kWh per month × $0.38 = $57 per month

If you ramped the solar speed to 1000w it would be this
4×150=600 + 8×1000=8000 8600/1000=8.6kWh×30 days = 258 kWh per month × $0.38 = $98 per month

 

[atttech-2]

I have a customer owned PV system and will be installing exchange panels for the pool this spring. I did extensive research before having the PV system installed some of what I discovered below. At the time I put the PV system up my tier 1 rate was $0.15 so the math has drifted a bit in favor of the PV system but the basic principals should still hold true.

Heat exchange panels are much more efficient than PV, but the PV system will work for you every day of the year vs just pool season so a mix can be a good thing. If you want to save as much money as possible the very first thing to do is reduce your electric demand a VS pump is a good start but if you have not already done so you should ensure your attic is well insulated, doors and windows are well sealed, hot water heater wrapped or go on demand system, all your lighting is LED or CFL, and you have as many energy star appliances as is piratical. I spent about 4K doing energy upgrades before I got the PV system that reduced my annual energy cost by about $600 a year. This also has the benefit of reducing the amount of PV needed another cost savings. I interviewed several PV installers and found that most, especially the ones that leas systems, just throw more panels at the problem and are not concerned with cost effectiveness of the system (why would they be your are paying for the system they want to sell the biggest one possible). An ideally sized PV system will completely eliminate your tier 2 and 3 usage but will not go too deep into tier 1 the reason for not building for a $0 electric bill is at tier 1 rates it would take near 20 years to break even, and most calculate the useful life of the system at 20 years it will likely last longer but that is a good rule of thumb. At $0.38 its less than 10 years to break even so the main goal should be get rid of the $0.38 tier.

I paid a little less than $4 per watt for my system and that cost was before the 30% tax credit so actual cost was a bit less than $2.8 per watt. That was April of 2014 I would guess the cost per watt has come down since then. My system uses micro inverters and at the time that was not what most installers were doing. I did pay a bit extra for that vs a string tied system but I wanted the freedom to add to the system later which I did my self a year later increasing the system size by 1/3 eliminating my tier 1 usage. By doing it my self I saved enough money on labor and markup to get the payback down to 8 years even at tier 1.

Bottom line I agree with gwegan a mix of the 2 is your best bet but make sure the PV installer is not over sizing the system to the point it is eating into the savings. in case your are planing on a lease be aware many of the contracts for leased systems will not allow pool solar on the same roof and If I recall correctly they have implications if you sell the house before the term is up. You either have to get the new owner to take it over, buy it out, or pay to have it moved.

One point of clarification is that facet of your roof truly facing east? Google usually defaults to a north/south orientation which would make it south facing, if it truly is an east facing roof and if I recall correctly that is the 3rd most desirable for any type of solar. South is the most desirable for sure, but I thought west was second, then east, and lastly north.

 

[Rossterman]

I'm in a similar situation and have similar rates, panels, etc. just interviewed the 4th solar company and looked at lease vs. buy. PV panels will net significant savings if you go the proper,direction. Here's some of the key learnings:

1. I reduced the pool solar panels from 10 4x12 panels to 6 which freed up enough room for a PV system. Pool still stays plenty warm (19k gal) and swimmable. Just not as quick to heat or get to 86 degrees where I like it.

2. Having companies use your roof to install their panels and sell you electricity at a lower rate (everyone was $$0.16/kw here with 3% yearly increase each year over 20 years.you will still have a significant electric bill but save 25-40% over current outlays. Some of the bigger companies (solar city for example) are deeply in debt and may not to $26be around in the next few years (this doesnt mean you get to keep the panels just that maintenance or other service aspects may decline).

3. Companies that install solar you own and maintain can design a system to significantly reduce or even eliminate you entire electricity cost. Like any industry, the pricing is all over the board. 8kw systems were qouted at $44k (sleezeball company the cold called me) to $26k. They typically,will,warranty work,for,five,years,while,the panels and equipment have 20 year warranties This allows you to keep the 30% tax credit but the deduction is only on any monies owed on your taxes. If you normally dont pay the IRS each year a significant amount, you will need to adjust withholding to make sure you underpay enough to subtract out the credit. Companies anticipate you recieving the rebate and artifically raise the pricing accordingly. Labor on both quotes was astronomical considering that installs are done by 2 or 3 workers in 1~2 days. Using the high bid as an example, $32k profit after paying $10k for materials and $2k for labor is a joke!

4. Companies sell complete systems online including the roof engineering analysis required by most cities. Systems install in a couple of days and require at least one licensed electrician to due tie-in and final hook up. Systems in 8kw range are ~ $12k while a building permit for the installation is ~$200.

In the end, a DIY system installed by you and a couple of friends is miles ahead cost wise compared to the option 2 or 3 with breakeven on your investment usually 2~3 years away. Meaning you pocket 100% of savings and after breakeven point where you have saved enough to pay for the intial cost is savings. These systems assemble very quickly and are almost plug and play compared to the initial designs. This is the route im going.

 

[atttech-2]

Owner install is certainly the most cost effective, if I had done my whole system myself the pay back would have been less than 5 years vs the nearly 10 I am at now. Having now seen the install I would go DIY if I had it to do again, but it was a bit daunting of a thought at the time never having seen one done. If you do consider DIY I would defiantly go micro inverter it is a much simpler install and as I mentioned before is scaleable.

 

[CaptainCannonball]

...One point of clarification is that facet of your roof truly facing east? Google usually defaults to a north/south orientation which would make it south facing, if it truly is an east facing roof and if I recall correctly that is the 3rd most desirable for any type of solar. South is the most desirable for sure, but I thought west was second, then east, and lastly north.

From my experience there are many factors, but I believe that pool solar order of preference would be south, west, east then north while PV would be south, east, west then north. The difference has to do with PV panels being more efficient at lower temperatures typically seen in the morning while pool solar is just the opposite.

 

[CaptainCannonball]

There is a lot of sound advice in this thread. I would echo the focus on efficiency and definitely lean toward turning that $500 expense into some savings. Payback will be faster than you think, even with factoring in additional costs for natural gas. Please shop around before picking a solar company. We paid $11.5 after taxes for a system that produced 8770kwh last year so our payback ends up being 4ish years. I'm not going to lie, it felt good making $400 worth of electricity last month.

 

[bobby1017]

I was in about the same position as the op of this thread. I now have a 12.1 kv ground mount system that was 44k before the tax deduction. I went oversize to allow for future electrical demands. My payoff was 6 years, only 4 more to go. As of a couple days ago my meter was 1463kwh lower than when the panels were installed 10/2014.

 

[Rossterman]

There is a lot of sound advice in this thread. I would echo the focus on efficiency and definitely lean toward turning that $500 expense into some savings. Payback will be faster than you think, even with factoring in additional costs for natural gas. Please shop around before picking a solar company. We paid $11.5 after taxes for a system that produced 8770kwh last year so our payback ends up being 4ish years. I'm not going to lie, it felt good making $400 worth of electricity last month.

thats a great price. Can you pass along the company you used?

 

[bobby1017]

There is a lot of sound advice in this thread. I would echo the focus on efficiency and definitely lean toward turning that $500 expense into some savings. Payback will be faster than you think, even with factoring in additional costs for natural gas. Please shop around before picking a solar company. We paid $11.5 after taxes for a system that produced 8770kwh last year so our payback ends up being 4ish years. I'm not going to lie, it felt good making $400 worth of electricity last month.

That comes out to 1.31 per kwh for you based on last years production, my cost is 1.50 per kwh based on after tax cost divided by 20565 kwh produced last year.

 

[CaptainCannonball]

thats a great price. Can you pass along the company you used?

Happy to PM you.

 

[CaptainCannonball]

That comes out to 1.31 per kwh for you based on last years production, my cost is 1.50 per kwh based on after tax cost divided by 20565 kwh produced last year.

I have never really heard of using that metric before for a yearly cost. I'm not sure what it really represents.

 

[bobby1017]

I have never really heard of using that metric before for a yearly cost. I'm not sure what it really represents.

I'm sure nobody has, it was just my way to see if the price / output was about the same, your a little better.

 

[mgill]

Thanks so much everyone for the commentary and feedback. Ive read through the responses once, I need to do it a few more times with notes and think through what I want to do. One quick note - I had rotated the google map picture so my house was straight up and down for the photo - the roof surface in the picture is in fact facing southeast technically - if I were to wager the direction of the roof with the panels is at about 125 degrees from north of 0.