I have been working on this for most of the summer. The problem with solar energy systems is that they are expensive. There is no doubt that a photovoltaic (solar electric) panel will save energy and pay for itself in time, however, the initial outlay of money to purchase and install that panel is more than most homeowner’s can afford. Solar thermal systems are likewise good investments, however, there associated systems are complex and need to be carefully designed and installed so that they function correctly.
What if someone could design a solar collector that can be easily built and installed by the average do it yourselfer. This is the idea that I had and I think I may have something.
Here are a few design benchmarks:
- That solar system would need to be fabricated on site with standard power tools.
- It should be constructed of material readily available at most home improvement stores and the like.
- The system should be simple and easy to understand and troubleshoot.
- It should be simple enough to construct that anyone with basic carpentry and metal working skills can build it and install it.
- It should be efficient and relatively inexpensive, paying for itself in one year.
Those are the basic ideas I had and I believe I met most of them with my design. What I was going for was something that would produce heat during the winter time and be optimized for cold snowy locations.
This solar collector is used to heat air, circulating air over a collector plate and returning it to the conditioned space. Air heating panels are simpler to construct than water heating panels, their downside is that there is no storage capacity associated with them. In other words, they work great when the sun is shining, but will not produce any heat at night. They are suplimental heaters in most cases and cannot replace a central heating system. That being the case, they can still save a significate amount of energy.
The main collector surface is made from aluminum drink cans. The cans have the tops cut off and are stacked horizontally like this:
This arrangement is more work and requires more materials but it has several advantages over other designs:
- Each can becomes a mini solar receiver similar to solar receivers used on large concentrated solar systems.
- The array of receivers gathers energy more effectively because there is less reflected energy than an ordinary flat plate collector. Once the energy strikes the collector surface, it is reflected down into the cans where the convex bottom aids in absorption.
- If mounted on a vertical south facing wall in front of a reflective surface such as a snow field or dry sand, the array will gather much more solar energy due to the increased insolation area.
- Aluminum is an excellent conductor of heat, thus the heat will move to the back of the collector plate, which will be cooled by forced air.
The main idea here is to make it simple yet effective. Aside from the collector, a 250-300 CFM DC fan and a PV panel round out the system. A small “snap disk” thermal fan switch turns the fan on and off depending on the collector temperature.
Part II will discuss tools and materials. I expect the system to cost about $400-450 to build. The most expensive item is the PV panel, which can be substituted with an AC wall transformer.
Part III will be a sysnopsis of my own system.