Thursday, November 24, 2011

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...


Sunday, November 20, 2011

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...


Tuesday, November 15, 2011

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!


Friday, November 11, 2011

Large 1986 Solar Space Heating System Marches On

In 1986 Mike Smith built his own home.  The home included very high insulation levels and a large (360 sqft) solar air heating collector.  

Mike's home with the large solar air heating collector.
After 25 years of service, the collector is still going strong.  Amazingly, in 25 years the system has required zero maintenance.

The hot air from the collector is ducted down to a rock bin in the basement to store heat.  When the house needs heat, hot air from the rock bin is ducted to the house.  A regular furnace provides backup.

The very good insulation levels (especially for 1986) allows the solar heating system to provide a large fraction of the home heating.

More examples from people who built great solar homes...


Tuesday, November 8, 2011

How Much Money Do You Save Installing Your Own PV System?

When we did our PV system two years ago, I did not really have a good way to evaluate how much money I saved by doing the install myself, let alone how this might vary over the country.  I knew how much it cost me, but, I did not really have a good number on how much an equivalent professionally installed system would cost.

Our 2.1 KW micro-inverter DIY PV array.
The Nov/Dec issue of Solar Today answered that question by providing a state by state installed cost per watt survey.  The current US wide average turns out to be $6.80 per peak watt.  

So, armed with this new data on what professional installs typically cost, I decided to update what our PV array would cost at today's prices and compare that to the $6.80 average professional install.  The results surprised me a bit.

Using the latest prices, a setup similar to what we put in two years ago would be about $3.30 per watt.  So, the savings for for DIY install is a bit over 50%.  For the 2300 watt system I looked at, this is a bit over $8000.  Not exactly chicken feed.

Being a fan of solar thermal I'll just mention that that the cost per peak watt for our $1K Solar Water Heating system is less than 50 cents a peak watt  -- Holy Cow! :)


Thursday, November 3, 2011

Solar Water and Space Heating Project With Unique Collector Design

Rob's new solar heating system provides both solar space and water heating.  The system is based on the $1K drain back design, but incorporates a number of very interesting design variations that may be helpful if you are doing a system.

Rob's finished system with the two hizer design collectors.
Side view of the collectors.
One unique feature of Rob's system is that the collector uses the new hizer design.  In most collectors the finned tubes that absorb solar radiation and transfer it to water flowing through the tubes run vertically with manifolds along the top and the bottom to supply water to the riser tubes at the bottom and collect heated water from the riser tubes along the top.  The hizer design was invented by Alan Rushforth to provide a more efficient design for wide collectors.  In the hizer design, the "riser" tubes run horizontally and the supply and return manifolds run vertically along the left and right sides.  The resulting horizontal risers have been dubbed hizers.  The hizer design results in shorter manifolds, and fewer riser to manifold connections -- a saving in both material and labor costs.   I

Rob's collectors are the first ones I know of to use the hizer design in a drain back system.  In order to insure that the collector water drains back to the storage tank (for freeze protection), all of the hizer runs are sloped slightly downward toward the supply manifold.
One of the collectors showing the hizer arrangement.
While Rob used two 10 ft wide hizer collectors, it would also be feasible to build a single 20 ft wide hizer collector.  For large solar space heating applications that might now use 5 or 6 or more side by side 4 ft wide by 8 or 10 ft wide collectors that must all be installed separately and plumbed together, the hizer design offers the possibility to build one large collector in place with with 25 or more ft long horizontal hizers instead of many many vertical risers.  It could be a real plus for wide, large site built collectors.  In addition to the saving in time and material, it is believed that the hizer design will be easier to get even collector filling and flow.

This shows the vertical manifolds being laid out.
Rob did a very careful job of working out the structural and plumbing details for the system, and much can be learned by just going through the detailed construction pictures and seeing how Rob handled the various construction details.

For space heating distribution to the house, Rob will be using a water to air heat ex changer mounted in the furnace ducting.  He plans to make some use of this same heat exchanger for summer cooling using well water.

Full details on designing and building the system...  (including a 42 page pdf)

Many other solar water heating systems...
Many other solar space heating systems...

An example of closed loop hizer design from Bob...

Thanks very much to Rob for taking the time to carefully document the system!


Tuesday, November 1, 2011

A Small, Portable PV System for Camping, Emergencies, ...

This is a nice, small, inexpensive, easy to build, very portable PV system from Kevin.  He uses it primarely for camping -- lights, radio, charging cell phone...   But, it also would make a good power source to have around in emergencies, and a good project to learn something about solar electricity.

Single box contains the charge controller, battery and other circuitry.

The system is all contained within the single box shown above except for the 50 watt PV panel.

The charge controller, meters, fuses and outlets are mounted in the box cover.

The battery (a deep cycle RV battery) is housed in the main part of the box.

An inverter on the back of the box provides 120VAC.

All the details on how to build Kevin's portable PV system here...

Many more PV projects of all sorts...


/* Start Analytics ---------------- */ /* End Analytics ---------------- */