Building Solar Heating Panels - Flat Black Paint Vs Thurmalox 'Selective Surface' (?) Coating

Check out my latest project: https://youtu.be/yXQnydST9fw I figured I should explain how the cost efficiency works out for me. I say for me, because the cost to build your own heater will depend on how savvy you are and the cost of building materials in your area, which will indisputably vary by region and especially by country. This can determine whether a selective coating vs flat black high heat paint is an economical choice for your DIY heater, or using the latter and simply increasing the collector size by X amount to compensate. To show what I'm talking about, here's a breakdown of my costs and the potential savings. One spray can covers ~15 sq.ft at the most. That's enough for one coat on one collector. The selective coating costs $25 USD, and I paid another $45 for shipping. $70 USD total. The flat black collector avg'd 1655 btu per hour, or 480 w/hr (refer to the link in the description). The Thurmalox collector avg'd around 1814 btu/hr, or 526 w/hr. Obviously, the Thurmalox coating is more efficient, approximately 8-9% more efficient on avg. We get roughly 4 sun hours (direct sunlight) on avg each day throughout the year in my area, which is around 1460 sun hrs in total. Being process heating panels and not seasonal direct space heaters, if the flat black collector were put to use for the entire year, it would generate around 480 watts per hour * 1460 annual sun hours = 700,800 watt hours, or 701 kWh. The Thurmalox collector would generate 768 kWh. In cost savings when compared to the local utility rate of 12¢/kWh, the flat black collector would gross around $84 in savings each year, and the Thurmalox collector would generate $92. The $8 in savings are in CAD $, too. It's equivalent to ~$6 USD. At that rate, it would take $70 / $6 = 11.7 years to pay off that can of Thrumalox, at least. The total cost for me to build each heater, minus the paint, was $350 CAD, or $255 USD. If I were to simply increase the collector area by 8% and use the cheaper flat black ($10 per can) instead of the $70/can selective coating, then that would only cost an extra $28 CAD per heater, or $21 USD. Same power potential with a cost increase that's 70% less than using the selective coating. But that's based on my costs. As mentioned, building material prices will vary by region, so people really need to sit down with a calculator and establish their own CBA to determine if it's worth it for them or not. Also, the can of Thurmalox 250 was only $25, but shipping it across New England and the Canadian border to me was $45. The shipping is what kills the idea for me. But I assume that it could be a lot cheaper (if not free) to ship within the US, so Thurmalox 250 could be a practical choice for Americans. You'll have to crunch the numbers for yourself to find out.

That bike in the background - teaser!

Another interesting project! I'm always impressed by how effective you are on your builds - loved the video!

Built one of these for the roof of my van last year when I camped in S. Utah in November. In 60 degrees, consistently reached 90 degree exhaust temps when flat on the roof but well above 130 when angled between vertical and horizontal. Also found that some air does not rise to be warmed so installed baffles to guide the air. I also drilled holes in the base for intake and found that hole size, placement, and angle effected time air took to warm. Creating turbulence inside the unit for me increased temps.

If I didn't know better I'd say this guy has done siding and metal work before because that was some excellent metal jointing

If someone has access to reclaimed double-glazing panels, this would seem to be an ideal use case. Refill with argon for that extra pep. As always, great video.

Dear James, ...... i need to think twice now to NOT use the wrong words to say what i have in mind. I'm blown away by what you do, how you do it, in what an energetic way you do things. I'm stunned, amazed, impressed and maybe even just caught by a person who's the perfect human i think does NOT exist very often these days anymore. I have a ton of Q's which i will NOT ask here at least not directly, but wow i wonder who that James Biggar is that is hard to find anything personal about anywhere? Me being a Bavarian from Germany of course, i'd think, this Guy has to have a German decent just because how PRO he is doing things and how he is taking care of certain details, then there is the part in that James, that runs around like NOBODY ever would see him, rubber boots, a key chain full as if he ones a hotel with 100 rooms and each a different key, a Dog Guy who enjoys working alone with his best friends on 4 legs only. Trying to be independent from most of the outside world, but then again a brain that is so untypical US American, it blows me away. Can a man like this James be living in the woods all alone or how in the world does a Guy like him get around, NOT being discovered yet, in whatever way you might want to read into this "discovered"? Watching your Vids takes time, but just by watching it's almost like a tough workout, in the inner need to find out more and figure out your drive and thoughts. As said, i'm drawing my own PROFILE of that Guy named James and you sure don't want to know what that profile looks like, but it's amazing to see what you do, how you do it and first of all . . . THAT YOU DO WHAT YOU DO! 👍🏻👍🏻👏🏻👏🏻👌🏻👌🏻 I'm amazed and as i'm from Bavaria i think i know what it's like to have a lot of forest and nature around, but seeing what you do and post on your channel ... it's STUNNING! All well done, very interesting and i need to "discover" more on your vids to see if there's an introduction of that James somewhere? GREAT work, cool from A-Z what you do and of course not to forget, who you are and the way you are. Back to make the basics fork for you and enjoying life in a different way. COOL👏🏻👏🏻😉!!! Sorry, need to go now, see more of what you do out in the US "rural" part of the Country 😄🤗🤗🤗 LOVE it, stay safe and healthy, all the BEST from Bavaria. CRAZY GOOD VIDEOS, i've seen so far from you!

Great work as always. Cant wait till I get a chance to make this.

Great video. I like the pleated diffuser in this solar heater. I built your other version with the flat angled diffuser, its working great but if it ever needs maintainance I will change over to the pleated design....

You are simply a genius!

Great work brother 👍👍

ty for all your hard work. Much appreciated.

Looks great, I love this one

Excellent video!!!

Awesome video!

you are number one man thank you

you should have a go at building solar thermal water panels. I'd be interested to see what design you come up with. I've already built a prototype and soon begin testing.

I need this in Himalayas of Nepal's remote village. Can you make a solar water heater too....Love the project !

Great info and great video! I made a pop can solar heater oh must be 15 years ago or so here in Woodstock NB on my old house using plywood, enerfoil dense foam insulation, sheet of Lexan (had a curved front), flat high temp bbq paint and pop cans obviously and white flashing around it. I remember getting real good results the curve of the cans creates larger surface area. Have any thoughts or read any on those types? I'm thinking of making another and stumbled on your channel and have gone gone down a bit of a rabbit hole with your video's haha you're very talented sir!

Could you please explain more? I don't get what had happened😓😯