Great Oak Common House Solar Hot Water Heater Proposal

We would like to install a 2 collector Solar Water Heater system. The proposed system has been approved for rebate under the "Michigan Solar Domestic Hot Water Rebate" program. Details of the program are found at http://www.urbanoptions.org/. The rebate program obligates us to have the system installed and tested within the next 70 days, so deciding on this proposal is time-critical.

The proposed system to be installed is described at http://www.btfsolar.com/specifications.htm and will be similar to the smaller system installed on Unit 24.

An example of an installed collector is:

though the collector shown is mounted on a flat roof like the proposed installation on the Common House's sitting room roof, facing south.

The system will consist of:

• one 80 gallon Solar Storage tank w/internal heat exchanger to be installed in the exercise room (28 in diameter and 62 inches in height, 336 lbs, with 4 protruding, insulated copper pipes, 2 on the side and 2 on top).
• 3/4" copper pipe with insulation to be run from the storage tank to the roof and piping through the wall into the existing hot water heater.
• one PV module and pump to pump antifreeze through the pipes, collector and heat exchanger and to pump water from the heat exchanger into the gas hot water heater
• a custom frame made of 2" x 2" x 3/16" aluminum angle iron or cold formed stainless steel channel upon which the collectors will rest. The custom framing will be attached to the roof with stainless steel lags bolts or carriage bolts through the sheathing or rafters bedded with polyurethane caulk
• 2 vacuum tube collector panels, approximately 33.1 sq ft in area each, installed on the shingles on the sitting room roof facing due south. The collector will be pitched a maximum of 60 degrees as to maximize solar exposure year-round.

The rebate program requires that the collectors be in full sunlight from 10am to 2pm. The trees on the south of the common house will NOT cast a shadow on the collectors if they are placed on the sitting room roof and will not need to be pruned or removed.

The following schematics show the sun exposure at 10am and 2pm on Jun 21st and Dec 21st. None of the shadow of the trees would fall on the collectors if they are placed on the sitting room roof.

The system will be installed by BTFSolar of Fennville, MI (www.btfsolar.com) and warrantied in its entirety for 2 years from the date of install. Individual components have different warranties ranging from 2 years to 40+ years.

Q. will the custom frame be installed on top of the shingles? when the roof is
replaced, will the roofers have to work around the collector/frame or can the
collector frame be moved for the roofing?

A. The frame would be moved to replace shingles underneath it.

Q. how heavy is the entire system that goes on the roof, including the custom
framing -- I see that the collector is 122 lbs, but what about the rest?

A. There is nothing else but the collector and the custom mounting adaptor
framing on the roof.

Q. the system has a 2 year warranty correct as required by the rebate
program? does that include fixing roof leaks that might be caused due
to the installation?

A. Yes.  And I have every intention of making sure that there are no leaks.
It is not to my advantage to fix leaks.  The penetration through the roof is
with two 1" holes that are flashed with copper shingle and polyurethane caulk.
I do a lot of roof ventilation work in Kalamazoo and am confident of leak
proofing such small openings.

Q. do you have references in Michigan that we can check with to see
how much they are saving in practice?

A. We have a system at the Michigan Area Renewable Energy Center  in Muskegon
of GVSU.  We donated over $2,000 hardware to them.   Please contact:

David Potter
Electrical and Mechanical  Systems Coordinator  MAREC
tel:  616 331 6903   
fax: 616 331 6910
email pottedav@gvsu.edu
http://www.gvsu.edu/marec
 
The collector and pump stand where installed last October by us.  The
completed installation was done this past spring (?).  They were
supposed to connect to computer software for data logging.  Perhaps
they can give you some info on performance in the worst location in
Michigan for solar applications, that's why we gave them equipment.


(I'm waiting for an email reply from Mr. Potter - Adi)

The entire system installed will cost $6540 minus a state rebate of $2800 as per the bid.
The hope is that the system will provide 20-30% of hot water used during the summer months and 10% during the winter months for an expected savings of up to $200 per year at current natural gas prices. Payback is expected within 20-30 years at worst.

Natural gas usage from DTE billing records, in CCF, for the GO CH:

2004
May 94
Jun 64
Jul 63
Sep 123
Oct 103
Nov 113
2005
Jan 510
Feb 710
Apr 529
May 56
Jul 73

• contributes a sustainable energy installation to the community, state and world, reducing demand on expensive, polluting and unsustainable resources
• a no-interest loan will be provided to the community by willing community members. Unit 24 is willing to loan the community enough to make the loan possible.
• shows the commitment to sustainability the community wishes to embrace
• serves as an experiment and hopefully showcases the role such alternative energy installations can play year-round in energy-poor Michigan
• will encourage other Great Oak and Ann Arbor cohousing units to consider similar systems
• takes advantage of a limited-time statewide initiative and incentive program

• possibly aesthetically lacking
• will require space in the already-cramped exercise room
• introduction of sealed holes in the roof decrease its integrity, though the included, proper, warrantied sealing should mitigate any problems
• the multi-year payback period means that the loan service will eat into the operating budget unless monies are loaned from the LTCRF account.
• No Michigan references yet -- might be worth waiting a year to see how other systems installed at GO units perform, but that might mean foregoing the state rebate.