Over/Around Window Solar Air Heating Collector -- Help!

 

The
Mother Earth News
folks have a strong interest in a solar air heating collector that works in conjunction with a regular window.  This is based on the long term popularity of the "Heat Grabber" collector that MEN published a number of years back.
While the Heat Grabber has been popular and works well, it does suffer a bit from limited collection area and, also because it sticks out from the building, which does not fit some situations.  So, the MEN folks are interested in anyone's ideas on how to improve the design.

 

The link below is my rough first prototype effort at a solar air heating collector that could be installed over a regular window.
The idea is to use the existing window to get air into and out of the collector.  This avoids any need to cut holes in the wall for vents.  It also makes it feasible to just install the collector over the winter.  Some design "challenges" remain.

So, have a look, and if you have any ideas to improve this design or have an alternative design, please leave a comment, or email them in.

Details on the prototype over/around window collector...

The first cut prototype over/around window collector.

The air ducting and screen absorber for prototype collector.


Gary

3 Ways to Save Energy That are a Bit "Out There"

Here are three areas where significant energy might be saved in a home with fairly simple systems.  One has to do with using some of the heat in the hot air up in your attic, and the other two have to do with recovering some of the heat we waste in showering.

Regular showers are a major waste of energy.  Typically we spend about 3 KWH heating water for a shower, and then send about 85% of that energy right down the drain.  It amounts to about 300 KWH for a family of 4 per month.

Using The Heat In Your Attic
This page looks at some of the ways that all that heat up in the attic might be used productively.  This includes recovering heat for domestic water heating, space heating, pool heating, and cloths dryer air preheat. 
Some of these look fairly practical (to me).

I've been logging the temperatures up in my attic for about 6 months and the plot of these temps is included.  We live in a very cold climate, and it still looks like there is some potential.

Details here...

Recovering Heat From Shower Water Drain Pipes
This page looks at all the energy we send down the drain when taking a shower, and in some of the ways that are currently out there to recover some of that energy. 
It considers one (as far as I know) new method, which is basically to rearrange the drain plumbing to retain the shower water in the homes heated envelope long enough to recover the heat in the water for space heating. 
Some ways of doing this, the resulting energy saving, and a small test to examine the potential of this method are discussed.

It may seem like there is not really much potential here, but for heating climates, the potential energy saving for a family might be of the order of 1200 KWH a year.

Details ...


A Very Energy (and Water) Efficient Shower Design
This is a look at a shower design that was looked at for potential use on very long range commercial jet airplanes.  It is a very efficient design both from a water use and energy point of view.  It may not be for everyone, but have a look.

Details...

So, I'm particularly interested in whether you think any of these ideas have some merit and are worth pursuing (or not). 
Or, maybe you have some of your own "Out There" ideas you would like to share?

UPDATE: Turns out Kenneth has built and uses a recirculating shower... 
Kenneth's interest were more in getting long showers with very high flow (6 shower heads) without breaking the bank on energy use.  Its a nice simple design.

Note that Kenneth has also done a very nice Solar Shed project that does both solar space and water heating -- hope to have the details on this up soon.
Thanks Kenneth!

Gary

New Content on Build-It-Solar

Pop Can Collector From Sweden



A very nicely done aluminum pop/beer can collector.  Lots of attention to detail, and lots of good assembly pictures.  In Swedish, but the pictures plus Google translator make it quite readable.
Pop can solar air heating collectors force room air through connected columns of black painted aluminum soda cans.  The sun heats the pop cans and the heat is transferred to the air.  The even distribution of airflow and large heat transfer area should make them efficient collectors.
Details here...

Update on Chad's Solar Heating System
Chad has made a number of changes to his solar water and space heating system.  He has also logged and measured the performance of the system.

All the details and performance graphs...

Efficient Inflation System for Double Skin Poly Greenhouses
Many
poly skinned greenhouses use two layers of poly with a small blower
inflating the space between the layers.  This gives you cheap double
glazing, and reduces heat loss.
Most of blowers are set up to run 24/7,
but this article shows a way to cut down the run time dramatically using a
small pressure switch and a very simple check valve.  With the check
valve, the blower runs only when enough air leaks out to the point of
needing reinflation.

Details here...



Facebook Page
I've put up a page for Build-It-Solar on Facebook. 
Basically I have no clue how this all works, so if you have any ideas for the Facebook page, please let me know.

We just broke 500 fans today, so have to be doing something right :)

Spring Solar Projects

Solar Hot Water

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Now is a good time to study up on, and start building a solar water heating
system, so you can get it in this summer.
There are several high quality DIY designs that cab be built for inside of $1000. 

 Many solar water heating
downloads
 




Solar Greenhouse or Sunspace

 A place to grow some plants, produce some free heat for the house next winter,
or just a nice place to sit and have a cup of coffee with the newspaper. 

 Many Solar Greenhouses and
SunSpaces  -- ranging from $20 to $200,000.

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Passive and Low Power Cooling

 Here are many ways to keep your house cool, and at the same time save money
and reduce Greenhouse Gas Emissions.  Shading, whole house fans, landscaping, earthtubes, insulation and sealing, reflective and garden roofs, ...
Lots of ideas here.
 Passive (and
efficient active) Cooling






Solar Pool and Hot Tub Heating
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 Solar pool heating is arguably the shortest payback solar technology.  
Take the chill off the pool, and be easy on the planet at the same time. 

 Solar pool heating
information
My favorite quote on solar pool heating from Tom Lane in the Home Power Article Pool Heating Article:
 "Three gallons of oil refined and burned provides 400,000BTU ... Once.
Three gallons of oil, made into a 4 by 12 foot solar collector, can provide
over 10 million BTUs per year ... year after year"


How about a Summer Outdoor Solar Shower?

This is a very simple solar project to get started with.  It can save energy and reuse shower water for plant watering while providing a nice outdoor shower experience!

How to build info for several outdoor solar showers...






Build Your Own Solar Electric System

Solar electric systems have become much easier to self install over the years.  If you are careful about the safety issues, and have done some home wiring, you may want to give this a try.  Plan it this spring, and build it this summer.

Details on my self installed system...

More on DIY PV...



Do a Water Conservation Project

Spring is a great time to get started on an outside water conservation project.
Dozens of projects described in detail here -- rainwater harvesting, greywater reuse,
rain water gardens, ...

All the details on water conservation projects...


Any other ideas --- make a suggestion.

Gary

Making, Buying, Designing, Evaluating Fins for Solar Collectors

Many of the homemade
collectors shown on this site use aluminum fins to collect the incoming
solar heat and transfer it to a tube that carries the heat transfer
fluid. 

The fins need to transfer heat efficiently, and need to have a good thermal connection with the tube carrying the heat transfer fluid. 

Copper tube with heat absorbing fin being installed.

This article goes over several fin designs, several ways of making the fins, some of the types of fins you can buy and where to get them. 

The new article also provides calculated fin efficiencies for some of the homemade and commercial designs.  I'm sure you are dying to know Which fins do best?  Does steel work as a fin material?  Are those big, thick, extruded fins worth the extra money? ...

All the details on fin design, fabrication, purchase, and performance here...

Some fin designs that people have sent in...


Kevin's two layer fin


Matt's bicycle powered fin former.


Tom's most impressive fin press

Got any ideas on fin design or fabrication?

Update March 11 -- I've added a couple more entries that have been turned in since this blog entry was written -- all on this page:

All the details on fin design, fabrication, purchase, and performance here...


Gary

Bob's Solar Ice Fishing Shack

This is a really simple but very effective solar heating collector that Bob uses to heat his ice fishing shack.


The collector uses the whole south wall of the shack.


The collector is a very simple thermosyphon air heating collector that uses 2 layers of black insect screen as the flow through absorber, and 6 mil poly film as the glazing.

Bob took the time to insulate and seal up the ice shack before installing the collector, which is key to making it work.   On a sunny day, it heats the inside of the shack up to very comfortable temperatures.

All the details from Bob...

If Bob can heat his ice shack with solar, you can surely heat your home, or chicken coop, or barn, ... with solar!

Gary

Storage Tank Kit for DIYers & DIY Solar Kits In General

The Softank is a kit for a 200 gallon water tank for heat storage.  The kit includes the parts that would be somewhat difficult for a DIYer to find or fabricate like the liner and the outer structural support cylinder.  The person building the tank buys the insulation locally, supplies some labor, and saves some money.

Details here...


Note: Heat exchanger not included with tank kit.

I like the Softank kit, but what I like even more is the idea that kits like this could be offered to home owners who want to build solar water or space heating systems.  These kits could bring building such a system to people with modest DIY skills, and also increase the likelihood of a successful build.  

Kits of this kind could include the difficult to obtain and difficult to make parts, while allowing the DIYer to buy readily available parts locally.  This approach avoids shipping large and fragile finished items like collectors, and would save the hassles, expense and CO2 emissions associated with truck shipping finished items.

Well designed kits and good instructions could greatly increase the chances of building a successful system -- even for not so experienced DIYers.

With commercial solar water heating systems selling for north of $8000, there is plenty of room for kit makers to earn a good profit and also save home owners lots of money.  A great opportunity for some new businesses!  How about it entrepreneurs?


Gary

THREE new Owner Built Solar Space Heating Systems

This has been a good week for new solar space heating systems sent in to Build-It-Solar!
Thanks very much to the Eric, Al, and Tom for describing there well designed and built systems. 
These are all large collector systems that can do significant solar heating -- lots to learn from the detailed descriptions of these systems.

The 1st is Eric's space heating and hot tub heating system that uses 300 sqft of water heating solar collectors, and has both a solar and boiler heat source.

The 2nd is Al's space heating collector that is primarily a solar air heating collector, but also has a smaller water heating capability integrated in the same collector.

The 3rd is Tom's new 330 sqft solar space heating system.  This system uses Tom's 3rd generation design for the copper tube, aluminum fin collectors.  This installment covers the design, build and install for the collectors.  The next will cover heat storage, plumbing, and controls.

See below for summaries, and the links for very detailed descriptions.

Al's Hybrid Air and Water Heating Collector
This is a very nicely done collector of about 100 sqft.  It is a space heating collector that primarily heats air that is circulated directly into the house.  But, it also has a smaller water heating capability that is used to store some heat for use during the night.


Its a nice looking collector that is well integrated with the house.

Since the collector area is about 15% of the house floor area, the collector will often generate more heat that can be immediately used on a sunny day, so it makes sense to add the limited water heating capability to store some heat for use later in the evening.

All the design and construction details from Al here...

Eric's Space Heating, Water Heating, Hot Tub Heating Solar System

This is a very nicely designed and built system from Eric -- a fellow Bozeman resident.
The system uses about 320 sqft of commercially made water heating collectors as its main heat source.  The collected solar heat is used for 1) space heating, 2) domestic water heating, and 3) hot tub heating.  The system also integrates a boiler as the secondary heat source.  



This is a pretty complicated system in that it heats floor space, a hot tub, and domestic water, and includes both a solar and boiler heat source into the same system. 
This is a difficult set of things to do, but Eric pulls it off with a pretty simple system.  Maybe the fact that he is in the HVAC business and specializes in solar system helps :)

All the details on Eric's system...

Tom's Large Solar Space Heating System
Tom's new space heating system uses 330 sqft of the aluminum fin/copper tube collector design.  This is about Tom's 3rd generation build of this type of collector, and he has a very refined design.   The collectors are mounted in a good looking common housing, and glazed with twinwall polycarbonate glazing.  Performance should be very good.



All the details on Tom's System...

Much more on Solar Space Heating Systems...

Gary

New Idea for Heating Domestic Water

Energy Alternatives has come up with a new design for heating domestic water.  Their design pipes water/antifreeze through several PEX pipes that are suspended in the attic ridge roof vent. 



The water heated by the PEX tubing is passed through a heat exchanger coil in a domestic water preheat tank.  The domestic water is preheated in this tank before it goes on to the regular water heating tank.

No real data is given on performance, and I suspect that for many climates, this is a three season heater at best, but it does offer an interesting alternative to solar, and it keeps the external look of the roof unchanged.

One article suggests that the cost of a 40 ft section of the PEX ridge vent assembly might be around $300, and that a full kit including the preheat tank with heat exchanger might be about $3100.

Here are some thoughts about DIY implementation of the ridge vent design that could (I think) be done for less than $1000 -- maybe substantially less.

Thanks very much to Chris for finding this and suggesting it!

Gary

Heat from Composting Biomass

I've been collecting material on the idea of extracting heat from compost piles and adding it to this section...

At first, this was a "that's kind of interesting" idea to me, but it has become more and more of a "that might really work" sort of idea.

Basically these schemes (there are several shown) start with a carefully constructed, large pile of biomass.  The biomass heats up as it goes through the composting process.  Pipes running through the pile pick up heat which can be used for domestic water heating and/or space heating.  Some schemes simultaneously collect bio-gas, which can be used for cooking fuel or even running a vehicle or generator.


Marc's compost furnace under construction.

A lot of work was done on this in the 70's by Jean Pain in France.  The section has some good descriptions of Pain's work, including two newly added videos (thanks to Curbie for these).

Marc's compost furnace work is very interesting, and includes some results from his first winter of operation.

The MB-Soft work in this area is interesting, if a little hard to decipher.

The New Alchemy papers are also quite good.

The attraction of this approach to me is that it holds the promise of a carbon neutral way of generating useful amounts of heat over long periods of time.  Some of the Pain piles are said to have been still generating useful heat after 18 months.  It is quite a bit of work to build one of the structured compost piles and set up the heat extraction plumbing, but then you may be able to get useful heating from the pile for an entire heating season.
The efficiency is claimed to be of the same order as burning the biomass -- maybe even a little better.  In many cases, the biomass can be material that would just be left to rot in place.

Does anyone have more useful information on this area?
Any thoughts on how useful and idea this might be?

Gary

First Year Performance for $1K Solar Water Heating System

The first full year of performance for the $1K Solar Water Heating system is in the books.  The graph below shows Solar Fraction by month.

All the details, and detailed plots that show collector, tank top, tank bottom, and ambient temperature are here...



So, this is the end of the promised one year of logging -- I now get my loggers back for other projects!

I've also a added a page that describes how I estimate Solar Fraction,
and considers some sources of error, and describes how my method
differs from the SRCC ratings of solar water heating systems.

Gary

Some New Content Items for Build-It-Solar

Three New Content Items

1. Lee's Solar Mower
Some time back, Lee sent in the details for his solar lawn mower.  The article basically tells you how to convert a gasoline powered mower to a battery powered electric mower with solar charging.
One issue with doing this is finding a good electric motor.  The one that Lee originally used is no longer available.  So, Lee has found a new source of motors that should work well and are cheap and easy to find....



2. Performance Update for Marc's  Compost Furnace

Last week, Marc provided a description of his system to provide space heating via heat extracted from a compost pile.
Marc has provided some performance data and other observations based on the first full season of operation...


3. A Home Built Grid-Tied PV System with Battery Backup
A
detailed account of the design and installation of a grid-tied PV system
with battery backup.

A home built ground mount system from treated lumber
is also described.

Heat Distribution For Solar Heating Systems

I added a section on methods of heat distribution for solar heating systems.  The new section provides links to a number of ways to distribute heat to a house for a solar heating system with an emphasis on DIY approaches.

Distribution of heat for solar heating systems is complicated by the fact that solar heating systems are more efficient when producing water that is not hot by boiler standards -- that is, boilers can easily produce 160F (or more) water, while solar heating systems are going to be more efficient when producing 120F (or less) water.  This makes the heat distribution more challenging, and makes some of the conventional systems difficult to use  because of their reliance on high temperature water.

If you have any additional ideas, please let me know. 

The new section is here....


A rather neat homemade radiator for heat distribution at the Dawson Creek, YT Visitors Center.

I also updated and added some material to the Heat Exchangers for Solar Heating Systems section...  Again, the emphasis is on DIY approaches.

Gary

A well designed compost furnace for space/water heating

Marc has worked out a what appears to be a very nice design for extracting heat from a large compost pile for space heating.



Marc's design includes a blower and air supply manifold system to aerate the pile, a pipe network to add water to the pile as needed, a pipe network to extract heat from the pile, insulation to increase the efficiency of the composting process, and a nice containment and cover system.

Link to Marc's blog entry on heat from compost...

Other heat from compost schemes on Build-It-Solar...

Judging from the emails I get, there is a lot of interest in using compost to generate heat, but there is not a lot of detailed information out there on how to actually build such as system.  I think Marc has taken a good cut at it.  What do you think?

Gary

Energy Fairs

This is the season for a lot of the annual energy fairs, so check around and see if there is a good one to go to in your area.

The fairs are a great way to learn about renewable energy projects, go to workshops, meet some renewable energy people in your area, and find some deals.

I keep a list of all the Energy Fairs I know about here...

If you know of others that are not on the list, please let me know...

Gary

Collector Fins from Tom's Super Press

Sometime back Tom built this super press for making the grooved fins for our homemade solar water heating collectors. Tom has indicated that time and material permitting, he is willing to make plates for others -- details here...

Tom is a long time friend of Build-It-Solar and has contributed plans for several very well done projects.



These appear to me be to be very well formed plates, and very likely will perform better than commercially made heat spreader plates.

If you are wondering what in the world this is all about, see this entry on construction the solar water heating collectors that use these plates...

Gary

Another very detailed "How-To" on Building PV Panels from Cells

On his website, Hange provides a very detailed set of instructions and pictures on how to build PV panels from individual PV cells...   The site covers finding cells, laying cells out to make a panel, soldering instructions, and glazing instructions...  



Several other articles on building your own panels...


Gary

Gordon's "$1K" Solar Water Heating -- From New Zealand

Gordon has provided details on how he built his version of the "$1K" Solar Water Heating system.  These systems are high quality, high solar fraction, all climate solar water heating systems that you can build for about $1000 in material costs.

Gordon's system adapts the design to his situation, his changes include:
- A well made, high tilt angle roof mount for the collectors.
- An all copper, single pass heat exchanger that pre-heats water before it gets to his existing hot water heater




Full details and build instructions on Gordon's Solar Water Heating System...

More examples of the "$1K" type solar water here...

Gary

Home Build PV Panels and System

In this new article, Hans describes in detail the solar electric (PV) system he built from the solar cells up.  The system includes 3 homemade PV panels, as well as the balance of system components to make a full functioning solar electric system. 

Full description of the PV system ...


Hans maintains a web site that provides more information on the project as well as other renewable energy projects.

Gary

Getting the 30% Federal Tax Credit on a DIY Solar Water Heating System

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I've received several emails from people who would like to
build the $1K Solar Water Heating System, but who also don't want to miss the
30% federal tax rebate that is part of the new Energy Bill -- I think you can
do this.

The new federal rebate for solar water heating systems offers a 30% tax credit on the full price of the system.

One of the requirements is that the collectors used in the
system must be certified by the SRCC under their OG-100 program.  Since its only the collectors that must be
certified, you can
build and install your own system and get the tax rebate as long as you use a
commercial collector that is SRCC certified, as most commercial collectors are.

As an example, if you were planning to build
the $1K system with a homemade 40sqft collector, you could substitute (say) a
Heliodyne Gobi 40 sqft collector .  This
will make the entire system qualify for the rebate.  The numbers might work out like this:

The $1K system costs                      $1000
Delete homemade collector         -$200
Add commercial collector            +$1000
--------------------------------------------------
Total cost of system                       $1800

Minus 30% rebate                            $540
----------------------------------------------------
Cost after rebate                              $1260

So, this approach increases the cost of the system a bit, but you get a nice shiny commercial collector, and avoid the work of
making a collector.  You also end up with
a solar water heating system that is about 1/5th the cost of a professionally
installed commercial system, and that will pay back your investment in a fairly
short period.

So, this is a good deal for you, and an even better deal for
the feds in that they are paying a rebate of only $540 instead of a typical rebate
of $2400 on an $8000 system -- as Barack would say, win-win!

Another approach would be to buy off the shelf components
for the full system and install them yourself. 
You save the cost of the installation, and you get the rebate.  Lots of material on how to install a system here...

Most states also have a rebate or tax credit program that might further reduce the cost of the system.  For example, my state (MT) offers a $500 tax credit on solar water heating systems with no stings attached.  Information on state programs here...

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Disclaimer: I'm not a tax expert, so you might want to do
some checking of your own on this.

Gary