Best Reflective Material for Solar Trough

What size is the trough?

It's 14ft x 45 Ft.

Aluminum flashing is readily available, made in fairly high volume and therefore not very expensive, but it does require some maintenance.

I'm trying to find supplier of metalized mylar (plastic) to evaluate it for durability, and so far, I've only gotten one manufacturer to respond.

The beauty of using aluminum is lack of corrosion.

A quick rinse as often as dust gathers is all that is required.

Maybe split aluminum dryer pipe, or the aluminized plastic dryer hose. Depends upon how much heat the reflector will be exposed to.

There is also shim stock on a roll.

The other thing is that some things may not appear shiny, but in other wavelengths it is, I have had this happen when taking a picture of a stainless steel sleeve that was all brown with river vegetation, the sleeve was bright and shiny in the picture later.

I have some experience with reflective Mylar. It shines like a mirror and holds up well under heat. The silvery backing can delaminate, but is otherwise stable. It should be 100% glued to its' backing or protected with glass. I would go the extra dollars for 22ga. polished stainless. for ease of installation, weather, and heat tolerance. You don't say where you are located, or what the ultimate use is, so it may or may not need glazing, or an antifreeze/heat exchanger, differential controls, storage, pumps, etc....

Use solar collector paint (has micron sized fuzz) or flat black hi-temp on black iron for your collector pipe.

Try aluminized Mylar. It is extremely thin ,.00025" and inexpensive. If you've ever seen the space blanket, that is aluminized Mylar. I have seem it used in a parabolic reflector by creating a slight vacuum behind it. The material is cheap $ 70/# ( 9000 sq.yd/#) enough to throw away when it gets dirty.

Here in Germany we have an aluminium foil, glued to a Styrofoam backing, about 4mm thick. Its for preventing heat from radiators being absorbed into the wall where the rad is mounted. Very,very effective.........and really cheap.

Its really easily glued with a glue for Styrofoam (most normal glues melt it!) onto any flat or curved surface, even complex curves can be covered with a few judicial cuts......very flexible.....

Any heat absorbed by the aluminium cannot get into the backing (well most anyway!) and eventually gets radiated back.

I feel strongly, if available in your country, that this is exactly what you are looking for....

I completely forgot to mention one of my main reasons for recommending this foil backed styrofoam.

Foil alone could do it, but is tricky to handle and glue, this stuff I am recommending is easy to handle and glue and makes a more profession looking job in the end...

Sorry about that.......

I have no experience building solar troughs "yet", but aluminum sheeting can be easily polished to a brilliant mirror finish using a simple cotton polishing wheel attached to a power drill. Use the wheel with aluminum specific cutting polish. If exposed to the elements, you'll need to repolish frequently.

I polished a Triumph twin using this method and it's blinding to look at in sunlight.

Dear friends:

Deeply thank you for your kind comments.

Rgds,

A formed glass mirror is best. The next is chromed steel. Aluminium is good but requires maintenance. The cheapest and shortest lived but also effective is alum-mylar film. All of these if your goal is a point of focus. I built a solar oven that used 10 1ft square mirrors to heat the black copper plate transfer behind a glass and insulating air. I put the mirrors on camera tripods and adusted then with help of others every .5 hr. A pain but effect enough to get temps of 350deg F for enought time to cook (warm up) a smoked ham.

Depends on your definition of "best". The performance/cost ratio is pretty high for aluminum spray paint applied to a smooth surface. The aluminum foil approach sounds pretty good for the money also.

Any coated aluminum will work well. Uncoated aluminum will oxidize turning white over time. Stay away from back surface mirrors they absorb a lot of heat.

Mylar is about the cheapest per % light reflected if you have it available where you are.

If you can afford to glaze the top of your trough, cleaning the glass is much easier than dusting the trough. And the reflective surface gets scratched up from cleaning over time.

I did some research and built some environmental chambers for agricultural testing around 15 years ago when mylar was still somewhat rare except for space blankets and it was the best value then. Now it is dirt cheap in comparison while reflecting 10-20% more light than aluminum foil (98%). The IR reflection is in the 80% range. If you can get gold mylar reflective film, it reflects heat even better. A quick search only found decorative gold mylar film with a 2 year outdoor life rating.

Brad