Solar Systems

Do you want to convert directly solar radiation to heat or you think about usage of PV (photovoltaic) panels which are much more complicated in designing and production?

http://www.uspto.gov/go/classification/uspc126/sched126.htm

This site is the US Patent Library listing for solar heat collectors et al. You should consider what is already patented. Many solar patents have expired, (over 20 years old) and can be reproduced by anyone and sold. Their description is what a patent is all about. Patents are required to be a description that would allow a person to produce the device that is described. If you are unsure if a patent has expired or not you can ask the patent office and/or the patent assignee for permission to produce the product described in the patent, if still in force. Becoming familiar with patents and the library itself is one of the best things I have done for myself. It is our common heritage of inventions, processes and incite.

Wading through all the hits on the Internet and all the manufacturers' literature will be difficult. Here are a few suggestions--

1. Balance your expenditures so you spend about as much on making the building energy efficient as you spend on solar.

2. Look at the entire structure when you do cost and payback analysis. Sometimes an item with a seemingly long payback can radically reduce some other cost, so the resultant total expenditure has a much shorter payback.

3. Anything you use follows Murphy's laws well. Plan for failures, storms, breakage, etc. Also, plan that the system(s) you install must fit the occupants' life styles and needs. You need to design the building and systems for the user, not the user for the building and systems.

4. Are you designing for active or passive, or a hybrid of these? Active solar requires some means of moving the energy from where it is collected to where it is stored and then to where it is used. This required energy input needs to be included in your plans, along with any required maintenance and reliability of this energy source.

5. Try using 90% ethanol (10% water) as your collector fluid. Assemble your collectors below the storage tank, with a receiver near the top of the collectors and the storage tank above the collectors. Fill the collectors with the fluid and continue filling until the receiver is about 1/4 full. Evacuate the entire system (until the collector fluid starts to boil). The resulting system is freeze proof, will remain below 150 PSI pressure even at stagnation temperatures of 155 deg C, and uses the vapor phase to transfer the heat from the collector to the storage tank. Since the collector fluid is food grade (90% ethanol is 180-proof, which is pretty close to Vodka's composition), you can use a single-walled heat exchanger at the storage tank, which significantly decreases cost. If you use a standard water heater and attach an external heat exchanger to the hot water outlet and the drain valve, storage tank cost and availability issues are greatly reduced.

6. Super-insulating your storage tank, even past R-60 is cost effective.

7. Be prepared to spend some money for a good engineer's review of your plans and work, and for good drawings. Well-written documentation for your systems is a must. Designing something to comply with multiple building and plumbing codes can be very difficult. If you can find an agency which tests and then lists your products and designs as complying with recognized standards (such as Underwriters Laboratories or Factory Mutual or National Sanitary Foundation), the additional expense of doing this will make code acceptance much easier. An alternative approach is to insist that the components you buy are all compliant with the desired codes or listed by the appropriate agencies.

Does any of this help?--John M.

Mr. Mueller.

I am impressed with your answer to the original question posed, particularly with the section on specific design considerations for the active fluid collection system. You have obviously had some hands-on experience with the design,installation and maintenance of these systems. I am a structural engineer in Canada and have for some time had an interest in high energy efficient homes. I would be most interested in seeing a copy of your drawings or sketches.

Lance White @ ldwhite@telus.net

Hi there. I wasn't sure if you're starting production as a manufacturer or if you mean as an end user.

We are just starting to import solar collectors into the UK from a manufacturer in China.

They are evacuated tube type, heat pipes with selective coating and are pretty much state of the art.

I'm afraid to say the Chinese have pretty much got the manufacturing covered. The products are superb, extremely good quality and cheap! Do a search for alibaba (a global purchasing portal) and solar collectors for more info.

What really gets my back up is that there are so many companies fleecing the public with solar energy products. In the UK it's getting to be just like the double glazing industry was. Yes there are profits, but not unreasonable profits to be made from gullible customers.

Regards

Andrew
GreenChoice

Andrew.

I have for a long while now been interested in purchasing an active solar collection system. Do you have a web site?

Hey Lance, didn't you mis spelt- your name ?

Wangito

Hi Lance,

I detect a little faux interest here. Solar technology isn't rocket science (there's a great play on words, if ever there was one). I'm sure there are dozens, if not hundreds of companies in Canada offering exactly what I'm selling. The basic principle is, the sun heats up a black surface, water flows through it, water gets hot. The fine detail is in selective surface coatings, absorbing more than just black paint, efficient heat transfer into the building and then efficient heat transfer into the water heating system.

As far as I know, no-one yet is offering inter-seasonal storage of space-heating requirements, although there are many precedents in one-off buildings. I myself am still hoping for some advancements in phase chage materials, such as Glaubers Salts for storing heat. I did a lot of study of this in the '70s and it looked very promisisng.

My bible is a book called Solar Energy and Building by S.V.Szokolay (US. ISBN is 0 85139 5694) It has some wonderful examples of both passive and active buildings since the '50s. It is a good read.

The panels I'm now importing were first produced by Philips in Holland for a house in Aachen, but were horribly expensive then. Now the technology is everyday stuff and made in tens of thousands by Chinese manufacturers. I'm not sure who it was who first came up with the idea of combining a Heat-Pipe (a wonderful invention on its own) with a top manifold and transferring the heat into flowing water. I would be grateful if anyone can enlighten me on that one.

The only hesitation I have is whether the heat transfer from the top of the heat pipe into the manifold is good enough. Normally you would enhance the efficiency of a heat pipe by having fins around the tube but this won't work where the tubes have to be disassembled and assembled. Again, I'd be glad of some comments on this.

I will happily sell you a system, I will even come over to Canada and design and fit it. I have a feeling that the payback time wouldn't justify the cost!

Still, if you'll meet me at the airport, we'll have a state-of-the-art system in no time!

Best wishes.

Andrew Holder

We have been a long time user of solar panels of different types. Don't kid yourself, It is much more involving than you may think. From the wording of your question I have to conclude that your knowledge of the subject is very limited. You have received some good advise here, and my advise to you is, if you really want to succeed, get a knowledgeable engineer to help you. If you plan to get the knowledge here at the CR, you're in bad shape. Especially listen to what a previous participant has to say on Chinese manufacturing. Very sad but true. One more advise, Israelis are the pioneers in that area, and have some very efficient and sophisticated systems. Try to get in touch with some manufacturers over there. May be done through their embassy, Most will happily sell you knowhow or distribution rights. Why invent the wheel?

Wangito.

BasOz

What is the latitude and elevation of your intended project? Or, if you are uncertain of your latitude, what country are you planning on installing your system within? How many sun hours do you experience during the day/year?

Also, the systems of collectors need to include storage systems in order to be effective. What kind of storage are you intending: electrical or heat? Your design has to include storage as well as collecting.

Mark

Very interesting comment from all of you, i manufacture structural insulated panel, and i am looking to add to my panel a solar system collector, we specialize in roof panel, up to 14' by 48', for industrial and residential in Canada.

The aim is to integrate that system to my panel, does one of your system could work for me...Thanks

I live in Morelia, Mich. Mexico, the insolation resource is good enough all year long. That is why, among other reasons (mid term economy, greenhouse gas emissions reduction, personal conviction), I bought a solar thermal system for water heating for my house. That was 12 years ago. It has been a success, I have my traditional boiler gas feeded system in parallel, so that when the solar resource (several cloudy days in a row) is not enough, I use the conventional heating system. But, in average, I would use this latter option only 10 to 15 days per year.

Needless to say I am totally convinced of solar energy. The system I have is not like the ones have been mentioned here, with evacuated glass tubes (european or chinese made). It is a simple copper set of tubes lay down under a black painted metal sheet, covered with a glass, and a thermal recipient that collects the hot water. There are many manufacturers in most countries with solar resource available.

Here, in my city, the small company where I bought my solar system, has 30 plus years manufacturing the devices. You might be interested in looking up his web site. It is www.captasol.com

Good luck in your search, and congratulations on your decision.

Genaro

P.S. I hope my english be readable, sorry for my misspellings and bad grammar structure.