Solar Space & Water Heating -- With Folding Collectors

Kenneth has incorporated some very nice and new features in his innovative solar space and water heating system -- including:

• Folding collectors that allow more collector area for winter and less for summer
  
  
• Some unique new tools for collector making, including a homemade "Tee Puller', and new designs for forming and clamping the collector fins to the collector tubes.
  
  
• Use of a surplus stainless steel bulk milk tank for heat storage.

The system is built using the Solar Shed concept, meaning its a separate building that acts as both a storage or garden shed, supports collectors and provides space for the heat storage tank.

A few hightlights below, and 5 pages of construction detail here...

Folding Collectors
The two pictures below show the folding collector feature. 



The top photo shows collectors folded out for winter -- 8 active collectors.
The bottom photo shows collectors folded in for summer -- 4 active collectors (along with Kenneth).

Homemade Tee Puller
Kenneth made a tool for drawing a Tee out of a copper collector manifold part -- this allows the collector risers to be connected to the manifold without using reducing Tee fittings or brazing.

Bulk Milk Tank for Heat Storage
Kenneth used a 750 gallon surplus stainless steel bulk milk tank for heat storage.
The tank is mostly buried (to allow drainback from collectors) and insulated with 4 inches of polyiso insulation.

Gary

Massachusetts Zero Energy Challenge Winning Home

This is a very impressive less than zero energy home.  It uses a
combination of reasonable size, excellent thermal envelope, very
efficient appliances, some passive and some active solar heating, and a
PV driven mini-split heat pump for additional heat and cooling.

The end result is a true zero energy house that can be built within a reasonable budget.

I cover a few of the highlights below, but all the details on the house are in the article here...

Performance
The monthly performance chart below speaks for itself.  For the year 2009, the house produced significantly more energy than it used.


Highlights
Double stud, R42 walls insulated with cellulose insulation.
R100 cellulose attic insulation.
Triple glazed R5 windows with R7 interior thermal shutters.
Very good infiltration sealing.
Emphasis on south windows for solar passive gain.
Concrete slab floors for heat storage thermal mass.
Solar water heating
Solar air heating collector to for additional space heating.
Exceptionally efficient appliances and lighting.
Heat recovery ventilation system.
Efficient mini-split heat pump for heating and AC.
4.9 KW grid-tied PV array supplies all electrical power and then some.

Double stud R42 cellulose insulated walls

Total cost of the house without land is $180,000.

Altogether, and exceptional house.

Thanks very much to Doug and Tina for providing this material.

Gary

Collector Absorber Fins from Tom

Tom Sullivan built a couple large water heating solar collectors.  To reduce the work involved in making the heat absorbing fins that go on the collector tubes, Tom built a very nice press to stamp out fins.

Tom has decided to make these fins available as a product from his UP Truck Center business.  He is offering fins to fit 1/2 inch and 5/8 inch tubing in lengths from 24 inches to 34 inches.  He also offers a sort of super fin option that achieves more wrap of the fin around the tube.  The prices are very reasonable, and I think this is a good option for anyone wanting to save some time on building the fins.

Here is the web page describing all the options and some notes on how best to install the fins...

Tom is a long time friend of Build-It-Solar, and has sent in detailed descriptions of some of his very well done solar projects...    Thanks Tom!



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

Zero Energy Homes for the Rest of Us

While visiting St George Utah recently, we found that we were in
town during the parade of homes, so we looked at a few of them.  One of the
display homes was a very efficient home built by Sun-Savvy Inc.  I was very
impressed by this home and the other homes they offer.

Their design combines a very good and very tight thermal envelope, heat
recovery ventilation, passive solar, solar thermal and PV arrays, and efficient
mini-split heat pumps to make a home that should be able to achieve net zero
energy use in the southern Utah climate.  The display home has a LEED
Platinum rating. 

Even more impressive to me is that these are very nice and very "normal"
looking homes.  These homes appear to be very easy for the homeowner to live with. 
While the energy efficiency does add some cost, the homes appear to be cost
competitive with ordinary construction homes.  In other words, these are
net zero or near net zero energy homes which should have a very wide appeal to
ordinary home buyers -- you don't have to be an eco-freak (like me) to like
these homes. 

We took the full tour, got a lot of pictures -- all the details here...

Much more on solar homes here...

Clerestory windows -- great daylighting.  These open automatically when a set temperature is exceeded.


The energy recovery ventilation unit -- an earthtube is used to precondition the intake air to the ventilator.

It seems like a lot of the "net zero" energy homes you see are a long ways
out of the mainstream -- they tend to be architecturally unique (some would say
strange) and come with an acre of PV panels that would add $100K+ to the cost of
the house were it not for some very very generous (and perhaps questionable)
rebate programs.  I don't see this type of near zero energy home ever
catching on and becoming widespread.  On the other hand, a design like the
Sun-Savvy homes seems like it could have very wide appeal.  I hope it turns into a trend.

Gary

Tom's Larger Solar Heating System

Tom sent in the final update on his new solar space and water heating system.  This update covers the storage tank, controls, heat exchanger and integration with the boiler.

This is a really interesting project.  It includes all of the following:

1. Design and construction of a 336 sqft solar collector -- including some new wrinkles on fin fabrication and installation.
2. Building the 410 gallon heat storage tank that doubles as a workbench.
3. Details on the solar  domestic water heating system that utilizes a heat exchanger made from about 200 ft of 3/4 inch rigid copper pipe. 
   
4. Details on implementing the radiant floor heating system that pumps hot water directly from the storage tank and requires no heat exchanger.
5. Details on adding heat input to the tank from a nearby wood boiler in a very simple way.
6. There is even a way to make use of solar heat on seasonal refills of a hot tub.

Tom's system integrates all of these functions in a simple, straight-forward and cost effective design.


Wood boiler heat source as alternative to solar.

Full details on Tom's space and water heating system...

Many other solar space heating projects...

Tom's other projects on Build-It-Solar....

Thanks again to Tom for taking the time to document this project!

Gary

A New Year -- Where to go?

2009 was a good year for Build-It-Solar.  4.2 million people visited over the year, and (more importantly) many stayed and read a lot.  I used to get excited when 200 people visited the site in a day, and now its well over 10,000 almost every day -- amazing!

I want to thank everyone who visited Build-It-Solar over the year, and sent in comments or questions.   And, thanks especially to those who took the time to send information in on their projects -- its these projects that make the site work.

2010
I'd like to make the site better during 2010  -- do you have any suggestions?

   - What do you like most? 
   - What areas do you find the most useful?
   - Where would you most like to see new content added?
   - What do you not like?
   - Any ideas for improvements format or presentation?
   - Any new areas you would like to see covered?
     
Some new areas I've been thinking about:
- The algae to oil area -- any chance of doing this on a DIY scale?
- A new area on solar/renewable for "home and garden" (solar tractors, mowers, lights, ...
- Adding an detailed "introduction" to each major area (Space Heating, PV, ...) that goes over the basics, covers some of the Physics, provides some design information,  and ties into the links and projects for that area.
- Doing a heat from compost trial.
- Working through the Passive House Institute software -- providing some pointers on getting started with it.

Perhaps building (with Nick and Nathan) a working version of Nick Pine's design for a "Deployable Doubt Dispeller" -- a small (e.g. 8 ft cube) "home" that would maintain a 70F inside temperature all winter here in Montana with simple active solar heating only.

Have a great new year.

Gary

1 Year Report on Gordon's Deep Energy Retrofit

A few months ago, Gordon and Sue sent in a very complete description of their project to completely remodel a poorly insulated and drafty schoolhouse for their residence.  There goal was to bring it up close to Passive House Institute standards.  Through a combination of an external Larsen Frame insulation scheme, added sun space, much sealing, excellent windows, and passive solar gain additions, they have achieved their goal.

The new sunspace added as part of the retrofit.


Gordon sent in the report after one year.  It covers performance to date (very good), and some fixes they have made to some problems that have come to light while living in the new home.

The very detailed report on the original project, including report, many pictures, and thermal analysis spreadsheet...

The 1 year update report, including performance to date, problem fixing, and updated thermal analysis spreadsheet...

This is the most carefully planned and executed energy retrofit I have seen, and it's really nice to see it living up to expectations.

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

Our New Grid-Tied PV System -- First Sun

The new PV system we have been working on putting in is up and running.  There are many pages of detail and a hundred or so pictures that go through the whole planning, design and installation process in mind numbing detail here...
Sections on performance and economics of the system are also included.




The system is a 2150 watt grid-tied system.  It uses the new micro-inverter approach from Enpahse -- so, each PV panel gets its own small grid-tie inverter.

The panels are ground mounted with our own mounting racks. 

We did the whole installation ourselves, and I've tried to include enough detail to be helpful to anyone who wants to install a PV system of their own.  I've tried to cover not only the details of the component installs and wiring, but also the stuff like deciding on what kind of system, locating the panels, doing a solar site survey, and going through the permiting and net metering process.  It should be enough reading to put you to sleep for a week of nights.



It was a technically interesting and fun project -- not having any previous experience with solar electric stuff, I learned a lot. 
But, the economics are also interesting.  Basically, the system cost was right near $10K or $4.65 a watt -- after rebates this gets down to $6.5K and $3 per watt.  Better than what I was expecting.  The $ saving per year if you pay 10cents a KWH would be $300, or about a 5% return on the $6,500 -- tax free and energy price inflation protected.
Not so bad, but when you compare our PV to well thought out conservation/efficiency projects, or to DIY solar heating projects its comes out a very very distant 2nd -- some examples in the Economics section.

I've fallen behind in getting other projects that people have sent in up, but now that the PV is done, I plan to catch up right after Thanksgiving -- so, keep the projects coming in!

Gary

Our New PV System

I've been trying to get the new PV system in the last week or so, and as a result I'm falling behind on getting new entries up on the website.  Thought I would just give a short progress report on the PV system. 

I do plan to do a new section with a lot of detail on the whole PV system process with lots of detail on design, site survey, mount construction, wiring, installation, ...   probably a lot detail more than you ever wanted to see :)

After much looking at a lot of options, I chose the type of system that uses one Enphase micro inverter for each PV panel.   In this kind of system, each PV panel gets its own grid-tie inverter, which is mounted right at the PV panel.  Each inverter takes one PV panel's DC output and converts it to 240 VAC that is grid compatible.  Each inverter plugs into the next inverter in the array, and you end up with all the power from up to 15 PV panels being available as 240VAC at the last panel/inverter in the string of panels.  My system has 10 PV panels at 215 watts each for a nominal total of 2150 watts. 

I bought the system as a "kit" from Wholesale Solar -- this one...

The more common approach on grid-tie systems is to wire several PV panels in series so that the they produce a high DC voltage.  This string of PV panels are then wired to an single inverter which takes the several hundred volts from the string of PV panels and converts to grid compatible 240 VAC. 

There are pros and cons to each approach, but (I think) both are pretty simple systems that can be DIY projects as long as you are VERY careful to mind the safety precautions. 

In my system, the PV panels are mounted on the ground and are located about 100 ft from the house out in the weeds.  The wires are run underground from the PV panels to the area where power comes into the house, and the grid-tie is made there.


I rented a power trencher to dig the trench for the wires.  In our hard soil, this saved a lot of time and effort.

After some debate with myself, I settled on a rather robust mounting system made from 4X4 treated lumber.  I wanted something that would withstand the high winds we get occasionally, and that would last 30 years.  Treated lumber may not be the best choice for long life in some areas, but around here, if properly installed it lasts a very long time.


This shows the framework that the PV panels will be mounted on. 
Anchored in about in 3200 lbs of concrete!



Running the wire (in conduit) from the house to PV array.


I clamped the PV support rails and a PV panel in place just to get the spacings
right and to plan where the inverters would go (they mount to the same rails as the PV panels)

This is where I am -- just waiting for a day or two of descent weather to finish it up.

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

Scott's 24 by 8 foot Space Heating PEX Collector

This is a really interesting solar space heating collector design.  It is built as a single unit that is 24 ft wide by 8 ft high.  Compared to building a bunch of separate collectors, the single unit construction saves some time, effort, and materials, and looks very nice.



The absorber is an extra wide variation on the PEX/aluminum absorber.

For more on the collector, including a link to Scott's site with all the construction details, and a few of my thoughts on the collector...

This is a good example of the kind of freedom to try new things and fit your design to your situation that building your own system gives.

Scott is a founder of the Yahoo SimplySolar group -- a good place to discuss your new solar ideas.

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

Installing Your Own Grid-Tie PV System

Guy Marsden goes through the whole process of designing, building, and installing a grid-tie PV system for his home. 


Guy and friends finishing the install.

The system uses the new Enphase micro inverters.  In this scheme, each PV panel gets its own inverter, which is installed on the back of the PV panel.  The output from the inverter is 230VAC.  The 230 VAC outputs from the inverters are tied together and hooked to your circuit breaker box via a regular circuit breaker.  Each inverter is UL certified for a grid-tie connection, so this is basically the all there is to it.  Power generated is monitored and reported by the Enphase Envoy unit.  The Envoy monitors and reports on each microinverter, and provides troubleshooting and power output reporting on the Enphase website.

Details on Guy's PV system...

Much more information on doing your own PV system...

While this system does simplify the installation, it is still a big job, and there are serious safety issues to be understood and deal with -- so, if you plan to do your own installation -- do your homework first!

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