Monday, February 27, 2012

Concentrating vs Flat Plate Collectors -- George's Tests

If you have ever puzzled over whether it would be better to make a regular flat plate collector or to make a tracked parabolic trough concentrating collector for your solar water or space heating project, George has done some really interesting side by side test comparisons of the two.

George's side by side test rig
The test setup George built allows two collectors to be mounted side by side.  Either or both collectors can be setup to track the sun through the day.  Each collector heats an identical insulated water reservoir, and the figure of merit is the water reservoir temperature over the day.

This is George's well written rundown on each of the tests and the results here...

Some of my thoughts on the test results...

Gary February 27, 2012

Tuesday, February 21, 2012

Solar Water Heating Kits or Packages

I've added a new section to Build-It-Solar that provides some info on solar water heating kits or packages.  These packages provide a full set of parts (collectors, tanks, pumps, controllers, ...) that allow you to install a solar water heating system yourself.

I've tried to aim at kit packages that are high quality, but still save s substantial amount of money over having a system professionally installed.    A typical solar water heating system for a family professionally installed runs about $8000.  These kits are in the $3000 to $5500 area.  You have to add a bit to that for a few things not generally included, but the savings can be of the order of half.   By comparison, a system that you build from scratch like our $1K system costs about (surprise) $1000.

The kits I've included vary quite a bit in design and come from large and small companies, and address warm and cold climates.  There may be something you are looking for.

I've also included some alternative approaches that are kind of between the  kit and and a full scratch build approaches.

The list is just a start -- I'm sure there are other good systems out there that I missed, so let me know if you know of a good one, or if you have installed any of these yourself, and how it went.

The full rundown on  Solar Water Heater kits...

The Solar Water Heating page with about 100 solar water heating projects...


Tuesday, February 14, 2012

Video -- A Home Built thermo-siphon solar air heater in Bozeman, Montana

Peter and Dana have finished the video on our themosyphon shop heating collector, and it looks great to me.

This is the link to the video on Peter's website...

Peter is a local builder and skilled video maker -- lots of interesting construction oriented videos on his site.

Paul, who you see in the video, runs  here in Bozeman will build one of these very fast payback solar collectors on your south wall.

Peter and Dana making moving pictures
For more on the details of building the collector...


Friday, February 10, 2012

Need help with sun simulator design

I've been doing a fair bit of solar thermal collector testing over the last couple years.  The way I do that is to wait for good steady sun, and then test the new collector design as well as a known baseline design side by side in the same sun conditions.  This works pretty well, but you have to wait for the sun, and you always have to test a baseline collector along with the new collector to account for sun variations.

To make the testing easier, I've been working on an inexpensive indoor sun simulator.  This gadget uses a few high wattage metal halide lamps (like street lights) to reproduce lighting levels similar to the sun on an up to 2 ft by 4 ft test collector.  This setup is looking pretty good, but I'm having trouble coming up with a reflector design  that puts enough of each lamps light output onto the collector.

So, if you have a minute and want to have a look at what the current sun simulator/reflector look like and pass on any ideas for improvements, I'd appreciate the help.

Details on the sun simulator and reflector ...

/* Start Analytics ---------------- */ /* End Analytics ---------------- */