1/2 -- Solar Energy Projects

These are the 5 solar energy projects we decided on:  3 completed -- 1 in-planning -- 1 future.

 

The totals to date for Solar Projects are:

14,600 KWH/yr energy saving. 

3.3 tons/yr reduction in carbon dioxide emissions.

$1,180 in energy savings per year.

Total cost of projects $4,900

First year return of 24%

Future projects include a sunspace and a solar electric system -- these will result in further decreases in energy use and greenhouse gases.

 

Again, your list of projects may be much different -- see the Planning Section. for ideas on making a good list.

 

My house is not well designed or oriented for solar heating.   It has a high heat loss due to large areas of glazing. These large glazed areas face ENE, so they have minimal solar gain in the winter.  But, with some effort, we managed to get the heat loss down quite a bit, and to design solar space heating collectors that will (in the end) provide half or more of the homes heat.  If your house is well oriented for solar, you may be able to do better for less work.

 

Solar Projects
 

Space Heating Water Heating PV

 

Solar Space Heating

Thermosyphon Shop Heater
This thermosyphon solar shop heater covers most of the south wall of my shop/barn, and is the only form of heat it has.

The collector is simple, cheap, efficient, and makes a good DIY project. The More Information link has the full description.

Note that if you heat a building that you use frequently with this collector, and you live in a cold climate, the  payback period will likely be inside of one year! 

More information
Energy Saving/yr 2527 KWH Initial Cost $350 DIY Labor 28 hrs
CO2 reduction 1323 lb $'s Saved/year $206 DIY difficulty 6
Energy Source Propane 1st Year Return 59%    
    10 yr saving (10% fuel inflation per year) $3282    
Cost Estimate:
The cost for all the materials was $350.

Dollar Saving:
I estimated the usable heat gain with a simple simulation that is similar to this  example simulation.
The results were that the collector gains about 13.8 Million BTU for the season.  This is equivalent to 187.5 gallons of propane when burned in an 80% efficient furnace.  I only used half of these estimates, because I do not use the shop full time, and would not heat it beyond keeping it above freezing on days I don't use it.

 

Direct Gain Collector
This is a direct gain solar collector that heats my shop/attached garage.  The big glazed panel doors heat the shop during the day, and the normal overhead garage door just behind the glazed doors is lowered at night to greatly reduce heat loss through the glazed doors.  The glazed doors also provide a far nicer environment in the shop -- bright and well lighted.  The More Information link has full details.

This is the now the only heat I use for the shop -- the furnace heat vents to the shop are closed off.

Update: This continues to be my favorite all around solar project.  There is a Home Power magazine article in the works on it.

More information
Energy Saving/yr 2912 KWH Initial Cost $380 DIY Labor 20 hrs
CO2 reduction 1525 lb $'s Saved/year $238 DIY difficulty 5
Energy Source Propane 1st Year Return 63%    
    10 yr saving (10% fuel inflation per year) $3784    
Cost Estimate:
The cost of all the materials was $380.

Dollar Saving:
I estimated the usable heat gain with a simple simulation that is similar to this  example simulation.
The results were that the collector gains about 10.5 Million BTU for the season.  This is equivalent to 127 gal when burned in an 90% efficient furnace.  I only used 85% of this to account for the fact that when it was heated on propane, I did not keep it as comfortable as it is with the solar collector.

 

Solar Space Heating -- Active Water Collectors
In Work: I am currently working on this project to add 240sqft of solar water heating collectors to provide space heating for the house.
The new collectors will be integrated with the south wall of our new garden shed (see picture).   See the More Information link for a complete description -- comments and suggestions welcome.
This has proven to be a pretty ambitious project (but I am further along than the pictures show).  When I look at the energy produced by the relatively simple solar air collectors compared to this one, it is certainly a vote for starting with simple air collectors.

Update: The Solar Shed has been up and running since early Jan '07, and is working well.  It is March 8, and snowing hard as I look out the window, but, we are still on solar heat from yesterday's collection stored in the thermal storage tank (which was up to 155.5F yesterday afternoon -- enough to keep us going through today without back up heat).
Update Nov 2007: still working well :)

More information
Energy Saving/yr 9170 KWH Initial Cost $4,200 DIY Labor 160 hrs
CO2 reduction 3800 lb $'s Saved/year $740 DIY difficulty 8.5
Energy Source Propane 1st Year Return 18%    
    10 yr saving (10% fuel inflation per year) $11,788    
Cost Estimate:
The cost of all the items that are chargeable to solar heating (i.e. not counting the new shed structure) is about $4200.

Dollar Saving:
I estimated the usable heat gain with a simple simulation that is similar to this  example simulation.
 

 

Solar Water Heating

Solar Water Heating -- Horizontal Pond Solar Water Heater
In Work: This is an experimental solar water heater that uses a pipe coil immersed in an insulated horizontal pond of water.  The pond has an floating insulated lid that is covered with EPDM, which acts as the absorber.  The pond has a slopped glazed cover that incorporates reflective sides.  When the sun is out, water is pumped onto the top surface of the floating lid using a small submersible pump in the pond -- the water is heated by the sun/absorber and then drains back into the pond.

This is an idea that I have been working on with Nick Pine, and we consider it experimental, but that it promises to provide all season solar water heating at a very low cost.  Comments welcome.  See the More Information link for details.
Note that the green house gas savings would be much greater if you  use electricity to heat your water.

More information
Energy Saving/yr 2200 KWH Initial Cost $350 DIY Labor 16 hrs
CO2 reduction  900 lb $'s Saved/year $179 DIY difficulty 5 
Energy Source Propane 1st Year Return 51%    
    10 yr saving (10% fuel inflation per year) $2851    
Cost Estimate:
The estimated cost for all the materials is $350.
Finding a pump that fits in this budget, and holds up to the temperatures is an outstanding challenge -- any suggestions?

Dollar Saving:
The energy saving of 2200 KWH is based on meeting 50% of the hot water demand for 2 people -- I believe that it will do as least that well.

 

 

Solar Photovoltaic

Solar PV
Future Project: I plan to add an approximately 1KW solar PV rig that incorporates 1 axis tracking.   The system is to be grid connected with batteries that are sufficient to give some minimal electric service during power outages.

The project has not been planned in any detail, but I've included it to show how PV compares to other solar projects and to conservation projects.

The DIY difficulty rating is just a guess, but is fairly high mostly due to having to deal with codes, inspections, ...
Energy Saving/yr 1708 KWH Initial Cost $9000 DIY Labor 40? hrs
CO2 reduction 3420 lb $'s Saved/year $170 DIY difficulty 8?
Energy Source Propane 1st Year Return 1.9%    
    10 yr saving (10% fuel inflation per year) $2720    
Cost Estimate:
The cost estimate is based on the $8 to $10 per peak watt -- so, (1000 peak watt)($9/watt) = $9000.

Dollar Saving:
The 1708KWH yearly output is from the PVWatts calculator for a 1 axis tracking system in SW Montana.

 

 

Green House Gas Emissions:

Green House Gas gas reductions were estimated like this.

 

DIY Difficulty:

In the project descriptions, "DIY difficulty" is a 1 to 10 rating of how hard the project is to do yourself:  1 being very easy, and 10 being "No chance I'm ever doing that again".

 

Economics:

There are a lot of ways to do a good job of calculating economic return -- Internal Rate of Return (IRR), Life Cycle Costs, ...  I think most of these just go right over peoples heads, so I decided on three less accurate, but very simple indicators: 1) dollars saved in fuel in the first year,  2) first year rate of return, which is just (first year $ saving/cost of project), and 3) 10 year fuel saving with 10% rise in fuel prices each year.  I think these give a pretty good feel for how good the project is economically without requiring an econ degree to understand?  If you have a suggestion for a better way, I'd like to hear it.

 

Note that my heating fuel is propane, which is a relatively expensive fuel.  If you use natural gas, your savings will likely be somewhat less for the same energy saving.

 

10 Year Cost Saving:

The "10 year saving" uses a fuel inflation factor of 10% per year.  This may be higher that what we will actually experience, but I used it as a measure of what would happen if fuel prices continue to go up at a high rate.  If you would like to use another factor, here are some others:

For 15% per year increase, multiply the first year saving by 20.30

For 10% per year increase, multiply the first year saving by 15.93

For  8% per year increase, multiply the first year saving by 14.49

For  5% per year increase, multiply the first year saving by 12.58

For  3% per year increase, multiply the first year saving by 11.46

For  0% per year increase, multiply the first year saving by 10.00

 

 

 

Gary 08/03/06, updated Nov 13, 2007