Welcome to the Solar Collector
Brainstorming and Development Page!


 

Home

Hot Air Collector

Hot Water Project 1

Hot Water & Space Heating

Solar Electric

Solar Construction 101

FAQs

Best Collectors

Simply Solar
Sign up Calendar Latest Topics
 
 
 


Reply
  Author   Comment   Page 1 of 3      1   2   3   Next
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #1 

Hi gang-

I've started working on the latest version of my ZeroPass Solar Heater. This will be the 3rd ZP I have built, if you include my original prototype where I did a direct comparison to the venerable 2-screen design, with favorable results. Version 2 performed far, far better. And Version 3?

My 2nd ZP was made from stud track in an attempt to make the it thinner and lighter for ease of seasonal moving and storage. It WAS lighter and thinner, but still far too heavy for me to handle alone. So I also made it in two 8’ sections in order to allow me to get it out of the basement workshop. Version 3 will also be built in two sections, although as I will explain in a moment, I might build it in two sections with final assembly into one single unit. Here is a link to Version 2:
http://simplysolar.supporttopics.com/post/gregs-new-zeropass-collector-7234542?trail=10

Last years stud track version was reinforced with 1/4” plywood on the back and sides. The plywood also gave strength, stiffness, and interior attachment points, which is a problem with stud track frames. But plywood also added considerable weight. While I could physically lift one end of an 8’ section, there would be no way I could handle a 16’ unit. Until now…The reason I added the plywood at the last minute was that I feared that seasonally moving and storage would wreck havoc on the collector and I’d end up having to repair, or even replace too often. So while this version will not have plywood sides and back, it should be plenty strong and light. How light? My goal is under 80 pounds for the entire 4x16 unit. While I still probably couldn’t lift that myself, I have a plan that will allow me to maneuver and mount the entire unit rather easily.

If you remember late last Spring Krautman built his 2nd ZP frame entirely out of ⅛” thick, 1” aluminum tubing. http://simplysolar.supporttopics.com/post/kraut-man-craig-and-his-zeropass-collector-7957395?pid=1291128089
He had pre-cut tubes welded together. Insulation was added between the frame pieces, and added an aluminum skin to the outside for protection. Like everything Krautman does, this thing is heavy duty. It's built like a tank. Considering he was a tank commander in Vietnam, it shouldn't surprise people. I can lift one end of his new ZP myself. Lift, Yes, Carry, NO! My construction will have many similarities. I will be using 1” aluminum tubing, but only half as thick 1/16” walls. I won’t be welding my frame, but connecting pre-cut pieces together with these:
http://www.estoconnectors.com

These fittings are made from a very strong and light, industrial plastic. They won’t crack or split, even in extreme temps. They should make a light, workable frame quickly and easily. The price is good too, about $2 per fitting. The fittings are designed to slip into the aluminum tubes quite nicely with the tap of a mallet. I suspect a peen to the tube or a bit of glue may be needed to ensure a secure fitting. These fitting are such that I may be able to build two separate sections in the basement workshop, bring them outside for final and permanent connection between the two halves. 

As far as the interior construction such as screen gap, I’d like to try the frameless screens like Krautman started working on, or Bert’s frameless version. I also like the two screen frames bolted together like Don is using. And while I’d LOVE to have a fancy controller to record temps, I’ll have to settle for something more basic for now due to money constraints. But have no fear, I can always add a controller at a later point via the easy access glazing assembly I will be using. I'd REALLY like to have this ZP running directly off of a solar panel. But with the CFM output the ZP needs, I'd have to have solar panel around 30 watts to run a dozen little fans or perhaps a couple larger fans.

Two years ago I talked my grouchy neighbor, Craig(Krautman) into building a ZP of his own for his workshop. Craig’s now finishing up his second ZP for the roof of his house. All that remains are the mounting stand and ducting. And late last spring Matt(mranum) built a ZP for his workshop too. And there are several others that have been completed, or are in final production. Craig, Matt and I already know how well the ZP performs. Bert, Don and others will soon know too.

So follow along as I build the next generation of my ZeroPass Solar Heater...

Greg in Minneapolis

Bert

Avatar / Picture

Registered:
Posts: 532
Reply with quote  #2 
Greg,
Looking forward to see how this comes together. I like those push connectors. They remind me of the leg adjustments on my folding table.
So you will be using 1" square tubes and skin them like Krautman did?



__________________
Bert K.
Michigan

https://www.youtube.com/user/1thinkhealthy/playlists
KevinH

Registered:
Posts: 560
Reply with quote  #3 
Any idea what your current collector weighs?  The weight adds up fast.  1" polyiso is 5.5 lbs, twinwall is 9 lbs, etc.  One place to cut weight is the backing.  All of my current collectors use the insulation as the back.  A lot of the weight can be shifted to the stand.

You would need a lot more than a 30W solar panel.  My 3-fan collectors draw about 23W each.  Your airflow is higher and the 16' length would require high static pressure fans which draw more current.  I have also wanted to power mine with solar, but the cost is still too high (unless I could find a use for the solar panel the rest of the year).  I would only save about 5 cents per full heating day which would probably be less than $6 per heating season.

Kevin H
MN
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #4 
I will be skinning the collector with something, but not sure what at this point. Aluminum sheets can be costly, and the panels made of plastic aren't able to handle the cold. I've even thought of using spray adhesive and applying a woven poly tarp. Durability is the biggest concern. Another concern is if the back isn't stiff enough, the back may flex slightly into the collector, as my collectors are exposed to northern winds. 

The only reason I'd like to try build using solar is to enable isolated locations such as barns, cabins, and sheds without power to have a heat source. I found several examples of small computer-type fans with the proper CFM and static pressure needs if a few were applied in a row.
http://www.digikey.com/product-search/en/fans-thermal-management/dc-fans/1179730

Many of them use less than 2 watts each. If I could mount them internally and run them directly from the correctly-sized solar panel, it might allow the fans to self-adjust fan speed to match the solar output. But as you said, the savings for buying fans and panels would cost a lot more than it would save.

I don't know how exactly how much my current collector weighs, but I'd guess it weighs about 200#. While a lighter collector is not as durable, it's less likely to be dropped or banged around since it is easier to handle. The new collector won't have a need for a stand, so there will be no weight will be transferred. 

Greg in Minneapolis
Bert

Avatar / Picture

Registered:
Posts: 532
Reply with quote  #5 
Don't forget about car radiator fans. some have CFM up to 2000 cfms.  They can be a bit noisy but if it's for a barn or shed it may not matter.  You would probably only need one fan that way.
I used this one for my smaller collector.
https://www.amazon.com/gp/product/B003908L3Q/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
1700 cfm. It worked pretty good even though my cinefoil tube collector had lot's of resistance. Was noisy but I added a speed controller and dialed it down when I was in the room.

It's 2.8 amps for 33.6 watts.




__________________
Bert K.
Michigan

https://www.youtube.com/user/1thinkhealthy/playlists
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #6 
I weighed last years ZP this afternoon while moving them onto their stands. Each 8' section weighs 96 pounds, for a grand total of 192 pounds. Too heavy and bulky to move even one section by myself, so if I can get the ZP3 in at half the weight, I should be good to go. I've not been well these last few years and I'm sure not getting any younger. And I'd sure like to be able to move a collector without help.

Greg in MN
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #7 
Bert-

i thought about 12V radiator and cooling fans, but I was thinking the fans would be inside the collector box itself. As it is I only have room for two collectors. Which means after I finish my new ZP3, I'll have an extra 2-screen collector to unload or sell. But before I sell, I want to build the ZPDP so I can compare the two. I want to see how much more BTU's the ZPDP can produce in the same 8' space. 

Greg in MN
dbc

Registered:
Posts: 252
Reply with quote  #8 
Greg - Looking forward to your new ZP design.  The Esto connectors could be a real breakthrough for frame design, allowing the collector to be built in sections but joined into a single unit during final assembly.  Another advantage is they give you some flexibility in the depth.  It gets kind of tight with the 3 5/8 stud track; with the new design you can have a little more clearance between the front screen and the glazing.

You mentioned you won't need a mounting stand - does that mean the new model will attach directly to the wall?  I know your 'version 2' model is in a tough location, with the back exposed.

I like the idea of a row of smaller fans mounted inside the collector.  This should help with distributing flow across the input, and lessen the over-pressure requirement for the input plenum.  If the fans are located right at the input of the ZP channel, the input plenum shouldn't have positive pressure at all.  I think others have gone this route.

I also like the 'elegance' of powering the fans from PV.  It may be tough to justify in purely economic terms unless you plan to install where there is no power, but having a 100% sun-powered system has a definite 'psychological' appeal that I feel is an important part of any solar project - hard to put a price on.  I know I feel like a kid whenever I see one of my solar projects working - almost a mystical thing!  One thing to check, though, is how much the fans cycle on and off when you have broken clouds on a generally sunny day; you might lose a little heat, since there is no 'time constant' with PV; when insolation drops, PV output drops right now.  Keeping thermal mass inside the insulated enclosure low might help with synchronizing the solar resource between the 2 systems.
stmbtwle

Avatar / Picture

Registered:
Posts: 2,839
Reply with quote  #9 
PV panels are a whole lot cheaper than they used to be, and they're "automatic"... when the sun shines they run, and you don't have to worry about a power failure ruining your collector. This one will run a 12" RV fan quite nicely. https://www.solarblvd.com/product_info.php?cPath=1_25_41&products_id=260
__________________
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #10 
Willie-

I haven't seen them quite that cheap. How many watts would I need my panel to be rated to run fans directly from a panel? For example, if have DC fan(s), totaling 20 watts, Does that mean I need a 20 watt solar panel? I would think you would want slightly more watts from a solar panel than the watts rating for all the fans since it's very rare to have perfectly clear conditions. If so, how much more? 

Greg in MN
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.

 

web statistics