Got a bunch of solar hot water panels, for free!
 

Today me and Ben Nelson took a road trip up to central Wisconsin to pickup some solar hot water panels that Ben's cousin had removed from her house a while ago. We had messed around with one of these panels a while ago and documented it here. The panels need some refurbishing work done to them. But, in total we now have 10 panels that are about 3'x6.5' for a total of 195 square feet of collector!

Here are some of the pics from the trip:

Here is what we found when we got there. The panels have been in the barn for quite some time with the glass off of them.
http://ecorenovator.org/pictures/house424.JPG

http://ecorenovator.org/pictures/house425.JPG



So, we loaded up Ben's truck with the glass first.
http://ecorenovator.org/pictures/house426.JPG



Then we stacked the panels on top of them.
http://ecorenovator.org/pictures/house427.JPG



A couple hours later we were back at my house with the panels all unloaded!
http://ecorenovator.org/pictures/house428.JPG




Ben has some video of the expedition that he'll share later. :)

Yeah, the best part was putting in the first sheet of glass and seeing that the tailgate wouldn't close....

We also logged our fuel use on the trip. We got 27.9 MPG with the truck carrying both of us, 9 solar hot water panels, and some assorted pipes, spare tire, and other gear. That was in the rain and the dark.

I'm sure if Tim was driving, we could have broke 30 mpg.... ;)

8 hours of driving... THAT was a long day. But hey, FREE SOLAR PANELS!

I'm just so glad nothing came off that X-mas tree truck we were stuck behind on the trip home.

Oh, also, we drove right past the headquarters of the Midwest Renewable Energy Association on both the ride there and back! If it weren't such back weather (and dark) I would have been tempted to stop and take a photo of our truck o' solar panels in front of the MREA.

Anywhoo - here's some video of our trip.
http://www.youtube.com/watch?v=C_lZlRQOsKw

Wooo, nicely put together Ben! Thanks once again.

I love the music selected... kind of upbeat, cheery, almost like a nice sunny warm day which is the exact opposite of the weather conditions the day we picked up the panels haha.

Nice price.

Why did the previous owner remove them from service? Where are you going to mount them?

That is exactly what I asked him when we met. When he bought the house the inspector said that they were hooked up to the main water supply and if there were any leaks it could likely cause some severe damage to the house. So, they had them removed.

As for mounting them, I'm still working on that. But, I think I have a spot picked out. The yellow line shows the approximate location.

http://ecorenovator.org/forum/attach...aragesolar.jpg


I did a solar site analysis on the location and there is some tree cover that will block sunlight. That is the difference between the winter and summer lines. My question (and I sent this to Gary at builditsolar) is how much sun generally gets through deciduous trees in the winter? Obviously it depends on how many branches are in the way, but I'd guess roughly 50% in general.

This is the site analysis from my height. I'm thinking I can probably put the panels up on stilts to get better sunlight in the morning hours in the winter time. The summer time won't be a problem as I've already calculated they'll more than provide all the hot water needs I have in summer.

http://ecorenovator.org/forum/attach...1&d=1289827502

Congratualtions on a great score on the SHW panels. I am, as they say, green with envy. :p

For a ground mount, it's generally a good idea to get them up in the air at least a little so that snow has somewhere to go.

I agree, I'll have to calculate how far I'll actually need to put them up to clear the obstruction.

Wow!:eek: Why can't I make a find like this???

Start looking. I think I started working on this one about 5 years ago....

On a daily basis, check Craigs List for "Solar" in the title, not description, check image.

You'll have all the solar HW panels your little pickup can carry...

-AC_Hacker

I did some rough calculations and made up a spreadsheet that shows how much heat these panels could provide and how much gas use they could offset. Its looking quite nice! Over the past year I used ~680 therms of gas. The solar panels will likely provide about 270 therms or 40% of my heating requirements, so a sizable chunk of energy savings! As I continue improving the house, that % will noticeably increase.

To compare, according to the cost savings calculator on builditsolar, my interior storm windows for my 13 sunroom windows will save me about 90 therms a year which is still huge. The interior storm windows will be TONS cheaper and easier to do though.

This is the break down month per month of the solar panel collection and my energy use.

http://ecorenovator.org/forum/attach...1&d=1291897515


Until it starts getting warm out (and I can start working on this project) I think I'll start keeping an eye out for cheap parts that I can use for the system.

Any update on this project? Noticed it been awhile since you updated it... this might be something I'm interested in for my house...

Ken
Lime Light Renewable Energy

Last time I had stopped over at the Doax residence, I saw that the giant snowbank covering the pile of solar panels had finally melted off.....

Hahahhahaaa... very funny. Having the same story with our place up in CT. Ground snow is finally melted, but not the plowed pile-up at the end of the driveway (still about 2 feet). Curious to see exactly how late into the spring it'll last. I think we're running into a record here...

@bennelson - btw: like your 300mpg site... happy to hear about Kwik-Trip and their "charging stations".

Ken
Lime Light Renewable Energy

Haha, no no updates here... yet. I am planning on building the rack and tank this summer, well, at least the rack and get the lines run to my basement. I've started drawing up the rack in SolidWorks to help me know what lumber I'll need for the project. I don't have anything worth posting yet though.

Evaluating Used Solar Panels...
 

Speaking of free solar panels, here is a brief list of tips for evaluating used solar panels.

I think we could do a better job.

-AC_Hacker

What exactly are you planning on doing with the hot water these things are going to be generating? Heating the house as well as the DHW? How are you going to go about it?

S-F, yep, the plan for the panels is to heat the house through in-floor radiant heat as well as domestic hot water.

I told Daox that he might want to get a hot-tub as well. Seriously, I have read quite a few mentions of using solar "waste" heat in the summer that way, when you don't need it to heat the house with anyways!

Yes, as Ben said, the panels will be for heating DHW and will assist in space heating through the use of hydronic radiant floors. As my chart shows, they'll provide quite a bit of heat (20%+ of my gas usage) even in in the worst of winter. My house is not all that efficient either (yet). Rough estimates show it saving me just under $400 a year.

The setup will be kept as simple as possible. It will be a drain back system to a ~400 gallon tank in my basement so no antifreeze. The DHW and space heating loops will need to go through their own heat exchangers inside the tank to pull the heat out.

Since my last post with that chart, I've tweaked it a bit to calculate things with the collectors at a specific tilt and also tweaked the collector efficiency per month. So, it should be a bit more accurate now.

http://ecorenovator.org/forum/attach...1&d=1308162755

So all we have to do is keep the cost of materials under $400 and you have a 1-YEAR RETURN ON INVESTMENT!

Heck, even if you spent $800, a TWO-YEAR ROI ain't bad either! :rolleyes:

10 solar panels for FREE is a good start. The materials for racking will cost a bit, as will the "water-box", but we're not talking $1000's here.

It'll definitely be interesting to see how much this ends up costing. It looks like $400-500 for the rack, but there is a lot of other stuff to add on. The piping to the tank (which is fairly large diameter, est. ~$250 plus insulation), the tank (~$500 estimated), and the heat exchangers will be another big costs. I wouldn't be too surprised if it got up to around $1500. However, I'll do it bit by bit and I'm sure some things will cost more and some will cost less.

How many gallons is the tank in the $1,000 builditsolar project? How are you planning on building your tank? This is all very important and interesting to me since I just bought a house and am either going to scrap the existing radiant system in favor of two small minisplits or do something like you are.

My tank will be around 400 gallons. I'm planning on making it very similar to Gary's solar shed tank which is also around 500 gallons. This is similar to the $1000 solar project one, just larger.

I do have a few changes I'll be making to the design and I haven't worked them all out quite yet. The tank is the next thing on my list to start working on. But, I know I will be using a different liner than he is. He used EPDM pond liners for his tanks and I am looking into using a paintable liner. The cost is less (~$100 vs $160) and thats the main reason I'm opting for it. It is also probably a bit easier to put in since the pond liner has to be folded. The other thing I'm thinking of doing is insulating more than most of have done before. I think his tank is insulated to around R30. I'm planning on insulating mine to at least R40. My insulation will also cost less because I'll be doing it mostly with cellulose (sealed from water of course) versus foam board.

You mean smaller.... right? Yours = 400 Gal. His = 500 Gal? The idea I've been tossing around involves doubling his tank. May quadrupling it. I like the idea of saving as much as possible but i like the idea of 0 energy a lot more than 20%. ;)

You are planning to build a box around the box and dense pack it? If it gets wet you'll be hosed! (no pun intended)

I'd highly recommend this setup for anyone in the same climate as me. I don't really NEED air conditioning so a heat pump isn't going to be used in summer much at all. I plan on using other means to cool the house (this is one example/possibility). Also, solar power is practially free once its installed, heat pumps do have a running cost even though it is pretty small compared to most other forms of heating. So, I think if you need to use a lot of AC, a heat pump would probably be better for you. If you don't need much AC, you can get away with a solar setup and some smaller form(s) of cooling.

Smaller than his $1000 solar hot water tank which is around 120 gallons I think.

I discussed larger tanks with Gary quite recently as I too was thinking about a ~600 gallon tank. The problem is that you can only use the water down to about 85-90F before you need to start heating it back up. DHW needs to be warmer than that even. If you have too large a tank, it might never get up to the temperatures that its really useful which is probably 110F+. Also, with a larger tank, you have more heat loss due to more surface area. You can negate this with more insulation, but it does cost more. Plus, my house is using way more than I'm producing daily, so that extra capacity is completely useless. Only if I had enough panels to produce more than a days worth of heat would I need to look into a larger tank. Then, I could save up for cloudy days.

This is where a small homemade heat pump can really help...

The heat pump can extract heat from your 85-90F storage tank and deliver heat to you in the range of 115-120F, as you probably need. My experiments have shown that the COP of such a heat pump working in the 80-90F range is quite high... on the order of 6 or 7.

As an added bonus, the chilled water left in the storage tank will present a higher delta T to the solar heat gathering part of your system, and increase the efficiency of your collectors when the sun starts shining.

Of course, when the solar collectors are supplying enough hot water to properly run your floor heating, you would not want to divert heated water through a heat pump.


Most hydronic floors like yours and Gary's are designed and built for cheap fossil fuel and have wide tube spacing, on the order of 12", and also have insulation that seemed quite reasonable when fuel was cheap. If hydronic floors were built to take advantage of lower feed temps (tube spacing on the order of 6 inches), you could still use 80-90 degree water.

Actually, larger tanks have a smaller surface area, per unit volume than smaller tanks, and lose heat more slowly.

This is why a cluster of bees can survive a cool night outside, but a lone bee will die.


-AC_Hacker

Thats all quite true AC Hacker. It made me rethink things (as well as S-F's comments). So, I ran my own numbers on using a 400 gallon vs 650 gallon tank. There are a few effects to consider.

First off, this change lowers the tank temperature. The reduced tank temperature reduces the heat loss of the tank due to the water being cooler. However, the tank is also physically larger, so it has more surface area to loose heat from. In the end, the larger tank does loose more heat, but the effect is very minimal. All in all, the 650 gallon tank looses ~300 btu per day more than the 400 gallon tank. This is nothing when you consider even in December (worst month for solar), my average solar heat input is ~79,000 btu.

Second, the tank change also increases the collector efficiency. This is because cycling hot water through a collector makes it picks up less energy. The panel also stays cooler and looses less heat to the environment. This is where most of the benefit comes from.

Lastly, going to a larger tank supplys you with cooler water. In my case, going from 400 to 650 gallons will likely lower the average tank temperature about 10 degrees (from 115 to 105F), and lower the peak temperature from 140F to 120F. 105F is just barely warm enough to shower, so some additional energy may be needed for DHW. However, 105F is fine for hydronic heating. Considering that space heating is by far the larger load and energy hog, I should primarily design to its needs. In addition for 6 months of the year I'll be collecting more heat than will be used, so hot water won't be an issue then.

All in all, going from a 400 to 650 gallon tank will allow me to collect about 6.7% more heat from the panels. I just need to be aware that I'll be dealing wih a lower temperature water and design accordinly for it.

This past weekend I scored another free bit to the solar panel setup. I was helping my father in law move a concrete sink (WOW heavy!) and he had this sitting next to it. A contractor ripped it out of the basement and it still seems to work just fine. We pressurized the bladder and it seems to hold air... I'm sure the size is a bit overkill for the panel setup, but hey its free and it'll still work great.

http://ecorenovator.org/forum/attach...1&d=1341890101

I've been thinking about this project a lot lately and have been wanting to get started on it again. However, I have a few other things that I'd like to button up first. Still, with the amazing weather this weekend, I took some time to work on the panels themselves. About half of the panels have been washed and rinsed. I sprayed them down with the hose and also put water through them with the hose. Hopefully I'll have time later this week to start pressure testing them.

That exp tank is not too big for 10 panels. In fact it might be a bit small and you will have to reduce the pressure in it somewhat. I would stick with a 650 gal tank and I would even look at making the panels on an 85-90deg pitch. IIRC your lowest sun angle in the winter is around 20deg and you don't want to deal with getting rid of hot water in the summer. Vertical panels will give you all the DHW you will need and make an efficient supply for the HP. All in all it looks like a fun project.

The mounting angle will be optimized for greatest heat gain in December. That does put it at about 20 degrees IIRC. I am hoping that the extra heat in summer won't be too big an issue.

Optimize it for when the sun just a bit higher than its yearly lowest, say for early Dec/mid January, since Jan/Feb are usually the coldest months.

As for the summer, I saw a house here yesterday which had half of its solar panels covered with a tarp.

Yeah, that might have to be a yearly thing if my tilt isn't steep enough. We'll see when summer rolls around.