An Easy/Good DIY LED Can Light Retrofit

Home Depot is selling a nice and easy to install LED retrofit for can lights.  We decided to try one as we have lots of can lights that would benefit from an efficient retrofit.

It is equivalent to a 65 watt incandescent, and has a 2700K color temperature -- nice and warm.   Output is 575 lumen.  Power consumption 10.5 watts.
Price is $40 -- kind of pricey, but see the payback comments below.  Claimed life is 20 years.
It is said to be dimmable, but apparently not all dimmers are compatible with it.


The 117 reviews on the HD site show a nearly 5 out of 5 stars with very few unhappy people.  Lots of very favorable comments.


The installation was relatively easy.  You take out the old can light bezel and remove the stuff holding the old can socket in place.  You then rotate out the little metal wings on the new fixture and just push it up into the old can housing -- very simple.  They can be removed by rotating the fixture CCW.

The springy metal pieces wedge into the existing can
light housing to hold the new fixture in place.

We also sealed up the openings and cracks in the existing can housing to reduce infiltration.


If you are going from incandescent bulbs to this LED, the saving is 55 watts.  This adds up pretty quickly.  For our usage and power costs, the payback period on saved electricity is only about 3 years. 


The lighting is very nice.

Nice warm lighting.

All the details on the installation and the payback calculations here...


Hundreds more conservation projects...


Gary

Solar Cooking After Dark -- A DIY Stored Heat Solar Cooker

Mik has been working on a way to collect and store solar energy during the daytime so that it can be used after sunset to cook meals.   He is looking for ideas to solve some of the technical issues that still remain, so if you have any ideas.

Reflector from satellite dish heating the bundle of iron rods.

Mik's solar cooker uses a concentrating reflector to heat a bundle of iron rods to very high temperatures.  Once the rods are heated, they are stored away in an insulated container to retain heat.  Later in the day (after the sun has set), the stored heat is used for cooking.

Diagram showing the design of the heat storage unit.

Cooking on stored heat.

While this is not the first solar collector to use stored heat, it is a very simple design that can be built fairly easily and cheaply in a low tech environment.  It could potentially reduce the amount of fossil fuel use by allowing people to cook with solar at normal meal times without regard to whether the sun is present at that time or not.

Mik has run into some material and insulation challenges in this project, and is looking for advice.

All the details on Mik's stored energy solar cooker... 
There is a comment section at this link.

Lots more on solar cooker designs...

Gary

Large Thermosyphon Collector Updates and Developments

I've been using a very simple solar thermosyphon collector to heat my shop for several years.  It is large and puts out a lot of heat -- its also simple, cheap, and low maintenance.  Where we live it has a kind of amazing one year payback on the cost of materials to build it.

The large thermosyphon shop heating collector

The collector has been getting some attention lately and that coupled with some new testing and 9 years of accumulated experience makes me think its time to do an update.  This update covers a lot of territory:

• A new commercial version of the collector 
• A video featuring the collector
• Potential changes and refinements
• Maintenance and upkeep over 9 years
• Testing effect of reducing vent size to make construction easier
• More accurate collector efficiency measurements

A New Commercial Version 

Paul House  of Choice Energy here in Bozeman  is offering a commercial version of the collector.  He will build one on your wall for about $2000.  In our climate, the collector offers about a 5 year payback (rebates could make it even shorter).  This is the best rate of return I know of for commercially installed collectors by a wide margin.  For example, if you compare it to the popular SolarSheat commercial collector, it is about 5 times more cost effective on a dollars per BTU basis.

All the details here...

A New Video on the Collector

There is a new video in works on the collector being done by Peter and Dana.  This is the first in a series of videos they are doing that will feature renewable energy projects in the SW Montana area.  They were out capturing video and audio before Christmas, and the final product should be out in a month or two -- I'll post a notice when its available.   I think this series of videos is going to be very interesting as there is a lot going on the renewable energy front in this area.

Paul and Gary on video day

Potential Changes and Refinements

The collector has performed very well, but, as always, there are a few things I would do differently if starting over.  So, this section lists a few small changes and one large change I would make.

The small changes have to do with details of the absorber installation, flashing, glazing...   just small refinements.

Collector cross section (from Home Power article)
The absorber change has to do with the tilt of the screen layers.

The one big possible change would be to revise the design to allow the collector to pass more daylighting into the shop area.  On my other shop, I use this glazed door arrangement, and I have to say I just love the solar daylighting it provides -- it not only helps when doing work, but it also just gives the place a more pleasant feeling.  I'd like to incorporate some some glazed area in the back wall of the thermosyphon collector that would add this solar daylighting feature.   If you have any ideas on good ways to do this, please let me know.

All the details on potential changes and refinements ...

Testing Smaller Vents

Paul suggested the idea of using a large hole saw to cut the inlet and outlet vents for the collector.  This would save some work and look nicer.  The potential downside is that a 6 inch or even 8 inch hole saw results in a smaller vent size than the design guide lines for these collectors specify.  

The two adjacent bays of the collector used to test
effect of smaller vents.

In order to get an idea what the performance penalty for the smaller vents might be, I masked down the vents on one bay, and then compared the heat output from this bay to the adjacent bay with the full sized vents.  Unfortunately, there is a pretty big penalty for the 6 inch round vents, and even the 8 inch round vents show a drop in heat output.  It looks like a 9 inch circular vent would be about right.

All the details on small vent testing...

Efficiency and Flow Rate Testing

While doing the small vent testing, I also had another go at testing the efficiency of the collector.  I have somewhat improved instrumentation and accounted for more of the odds and ends that effect efficiency.  Its difficult to get good efficiency measurements on any solar air heating collector because measuring airflow accurately is hard.  Getting good airflow measurements on the thermosyphon collector is even more difficult due to the large vents with low vent velocities.    But, I do think these new measurements are pretty good.  

Bottom line is that for the full sun, moderate winter day I tested on, the efficiency comes out between 62 and 65%  -- this is really very good, especially considering how simple and inexpensive the collector design is.

Logger plot used for vent size and efficiency estimates.

There are also some test results on collector flow rate, dust filter effects on flow rate, and on using the back surface of the collector as a radiant room heater.

Details on collector efficiency measurements...

Maintenance 

Through the first 9 years, the collector maintenance has been very minimal.  

The poly back draft dampers have been replaced once at a cost of 2 cents per damper.

I painted the outside of the collector frame last year.

The fact that the collector does not have a fan or controller eliminates the two most maintenance prone items on solar air heating collectors. 

After 9 years, the polycarbonate glazing still looks very good.

All the details on maintenance over the last 9 years...

If you have any thoughts or suggestions on the collector, please let me know.

Collector parts diagram (from Home Power article)

All the details on  simple solar thermosyphon collector

Gary

January 6, 2012

Restoring an Elec-Trak Tractor and Integrating it With Our PV System

Last summer, we bought a used Elec-Trak tractor -- I suppose "used" is a bit redundant since the last Elec-Trak left the factory in the 80's.

Our "new" Elec-Trak after some TLC.

The Elec-Traks are all electric tractors powered by a set of on-board lead acid (golf cart) batteries.  They were made by GE for several years during the 70's, and were popular with more than 30,000 made.  They are very durable and functional machines with a wide range of all electric accessories.  The Elec-Traks have a strong following with an online owner forum and good parts support.   Many of these tractors have been rebuilt and are serving people well.  Being electric, these machines are cleaner, cheaper to run, and low maintenance than equivalent gasoline models.

The Elec-Trac with new charger/inverter supplying 120 VAC power out in the field.

In addition to the usual mowing and snow blowing tasks, we wanted to be able to use the Elec-Trak to power our home during power outages -- it has a large enough battery pack to power a few critical loads like the fridge and furnace for something in excess of a day.   This proved to be a relatively easy thing to do using a commercial charger/inverter from Tripplite.

In addition,  we wanted to work out a way to use our grid-tied PV array to charge the Elec-Trak battery pack during power outages.  This proved to be more of a challenge in that grid-tied PV arrays are designed to stop operating as soon as a power outage is detected, and to stay offline until the grid comes back.  After a bit of head scratching, we did work out a way that is fairly easy and effective if not terribly elegant.  The nice thing about our arrangement is that we get most of the benefits of a grid-tied with battery backup PV system, but without the considerable initial expense of these systems and without the need to maintain and replace a set of batteries that is almost never used.  See the link below for details.

Charging the Elec-Trak batteries during a simulated power outage using our PV array.

All the detail on our Elec-Trak project -- from scraping and painting to integrating it with our grid-tie PV system -- about 20 pages in all...

More Elec-Trak stuff:
For a rundown on the history of the Elec-Trak and a description of the various models, see Mark's article...

The Build-It-Solar section on Elec-Traks and similar electric machines...

One of my favorite Elec-Trac sites is George's My Elec-Traks site...  He has restored just about every model and also has lots of the Elec-Trak manuals and brochures.

The online Elec-Trak owners forum...

Just a bit of rust to clean up.

The new charger/inverter rides with the Elec-Trak when power is needed for 120VAC loads, or can stay back in the barn for charging.

The new charge controller that allows the grid-tie PV

array to temporarily be used as an off-grid PV array to charge

the Elec-Trak during power outages.

Gary

December 21, 2011

Solar Site Survey Based Aerial Photos

Bright Harvest offers a somewhat unique solar site survey.  They use aerial photos of your house to build a digital model, and then show you alternative arrangements of collectors.  They also model any shading objects near your home, and show the monthly and yearly effect of this shading on the output of the array.  Estimates for yearly output are also shown.

Overview of the model and panel layout with shading.

They offered to do a survey of my house, and I took them up on this and the link at the bottom of this post is to a page with the details on the survey and some thoughts on it.

In a nutshell, I was favorably impressed by the survey.  They did a good job of identifying potential PV array placements and a good job of finding shading sources.  Even though I've done a couple "manual" solar site surveys on my home myself, they found some things that I had missed or not thought about.  

The cost of the survey is not trivial at $150, but it may well be worth it to get a good handle on shading -- especially for complex situations.

I would always recommend doing the "manual" solar site survey yourself, as it will make you aware of how the sun interacts with the house and shading objects over the course of the year -- its just something everyone should do before tackling any solar project.  But, if you are uncertain about the shading situation or array mounting possibilities after the manual survey, the Bright Harvest survey or a SketchUp model would be a very good follow up.  I get a lot of emails from people who put their collectors up, and then come to find that the shading situation is worse than they thought -- it is just very important to have a good handle on shading before starting.

Full details and comments on the Bright Harvest report on my house...

The "manual" solar site survey you can do....

Gary

December 16, 2011

DIY Solar Garden Helper Machine

This is Randy's pretty amazing solar powered garden helper machine.

Randy made the machine to make it easier to do the planting, weeding and picking chores in the garden.  The seats on each side are adjustable side to side to accommodate wide or narrow rows of plants.  The speed control is a joystick that can be mounted left, right or center.

The frame is made from 1 inch welded steel tubing.  It is solar powered using 4 golf cart batteries and two on board 80 watt PV panels that also provide shade for the driver.

The drive train is from an electric wheelchair, but is geared down for more torque.  Maximum speed is about walking speed.

Thanks very much to Randy for making this available!

All the details on Randy's solar garden helper machine...

More solar powered garden tractors and lawn mowers...

Note the batteries over the rear wheels for more traction and
less weight on front wheels for easier steering.

Gary

Greenstar Blox -- A New Energy Efficient Wall Block

Greenstar Blox are a new wall building product that has been under development for several years.  The Greenstar Blox offer the promise of high strength, durability, high R values, reasonable cost, and a relatively straight forward build process.  It looks to me like they might make a good material for owner built homes.

A Greenstar Blox project

The standard Greenstar Block is 10 by 14 by 4 inches and is made from roughly 65% selected recycled paper, 25% Portland cement, and various additives.  This is similar to papercrete, but the difference is that Greenstar Blox are commercially made to a standardized recipe  using  a standardized process to produce a consistently high quality block.  The Greenstar Bloxs are currently going through an extensive testing program at Texas Tech University.  The results of the testing program are being used to seek building code approval, which is anticipated in early 2012.

The blocks are laid in courses as usual (kind of like Legos).  The mortar is made from the same
material that the blocks are made from.

The blocks appear to be relatively straight forward to build with.  They are much lighter and easier to handle than concrete blocks.  They offer the big advantage of a high R value right in the block without the need for additional layers of insulating material.   Greenstar says that walls made with their blocks will be about R25.  


An important item for anyone thinking about building with these blocks is that building code approval is in the works -- this will make it much easier for people wanting to build to get building permits.


I'd love to hear from anyone using the Greenstar Blox.


Notes from a consversation with Greenstar Blox...


The Greenstar Blox website...


Gary

Boat in a Hole -- George's Unique Rootcellar

Could not help passing this on.
This is George's solution for a cost effective, relatively easy to build, and very functional root cellar.

After thinking about a number of ways to build a root cellar for their new place, they tumbled to the idea of using a fiberglass boat hull.  It turns out these are available for reasonable prices.   They provide a good, waterproof and strong root cellar.

Buried for root cellar use.

They use it for both a root cellar and also as a bunkhouse.

The entry.

While I suppose this might seem a bit sad to some boat owners, George points out that there are a number of derelict boats around that will never see use again, and this is a 2nd life that I'm sure any boat would like a lot better than just rotting away unused.

George's full description of the boat for root cellar...

More on various root cellar designs...


Gary

Flow of River Hydro -- Using Only Stream Velocity to Drive a Turbine

I get email questions from people who live on a stream and would like to use the stream to make electricity.
If the stream has some elevation drop over the property and the flow is decent most of the year, then the answer is that if you can meet the legal requirements, its possible to make electricity, and that it can be quite cost effective.

Quite a nice underflow water wheel.

But, if the stream has no elevation drop, and you just want to make use of the velocity of the stream water to make electricity, then its more challenging.  I've added a new section that goes into what's involved in generating electricity only from the water velocity.  It covers how to estimate the amount of power your stream might generate, provides a bit of design information, and it lists all of the home scale example projects I could find that seemed like they might actually work.  Its a place to get started on your quest for free no pollution energy from your stream.

One of the reasons getting power from your stream is difficult is that while its clear that there is energy in that flowing water, it not nearly as dense as the energy you can extract from water dropping through an elevation difference.  This plot shows you roughly how much power you can get from 1 sqft of flow area at various stream velocities.

Just a glance will tell you that if you have a 2 mph 6 inch deep stream, your power generation possibilities are pretty limited.  But, if you have a deep 5 mph stream, there is some worthwhile power there.

I found a few commercial and few homemade examples of flow of river turbines and water wheels -- the link below provides pointers to all the ones I could find.  If you know of others please let me know.

The new section on Flow-Of-River hydro installtions...

The micro-hyro page for info on more conventional hydro...

Gary

Bottom-Up Insulating Shades for Light and Insulation -- Our R8.3 Window

On some of our windows that we have no need to look out of, but still want some light, we use a 3/4 insulating shutter on the bottom of the window.   I like the 3/4 shutter idea because it does a very good job of insulating most of the window, while still letting a lot of light into the room.

The 3/4 shutter got us to wondering if a top-down/bottom-up insulating shade could be used in the same way -- we decided to try this on one of our windows.

Our first try at an insulating top-down/bottom-up shade.

This window is a bit odd with the triangular top, and I had to add a support board to hold the top bar of the shade in place.

This arrangement allows us to have the shade fully up at night for privacy and maximum insulation, or during the day to have the shade part way up to allow more light and views with some insulation.  Normally we would have it up more than the picture shows during the day to get somewhat more insulated area.

The new shade is from Symphony Shades and in addition to being a good double cellular insulating shade, it has side tracks that reduce air flow around the sides of the shade.

The side tracks prevent airflow around the edges of the shade.

Closeup of track showing notch in shade that track engages.

It turns out that this window already has a double Mylar inside storm window on it (bet you could not even see it :), so the total insulating value is:  low-e window (R3) + double Mylar storm (R2) + insulating shade with side tracks (R3.3) is a sort of amazing R8.3!

Gary