24 VDC Solar Off Grid 120 Square Foot Building

© Brooke Clarke 2011

This is a combination of ideas. 

• There is a no permit required building allowed here if it's under 120 square feet and meets other provisions.  This only applies to storage sheds, not to this idea which is what's called a work shop and requires a permit.  Cost drivers for buildings are the length of the preimeter, area of ground covered, exterior area, etc.
  
• Some of my H.F. military surplus radios (GRC-206, GRC-193, PRC-104, etc.) work best when the radio is very close to the base of the antenna. 
  
• These radios run on military vehicle DC power, i.e. "24 Volts DC". 
  
• It's very expensive to get a  household A.C. power supply that has enough power to provide 24 Volts DC. For example the PP-6224B/U 24V Power Supply does not have enough power to drive the complete GRC-206 system, only one radio at at time.  The M455-1/GRC-206 Power Source requires a magical connection scheme that no one has figured out yet.  But a lead acid battery can easily supply the power needed since that's what's used in a military vehicle. 
  
• Instead of mounting the radio into a real military vehicle (an expensive proposition for a vehicle in good running condition (M151 MUTT Jeep (plain or A2 or one of the HMMWV Hummer 1 ¼-Ton, 4X4) and hard to find.
• The radios work better with the larger antennas that are transportable or fixed (TCI 651T, Special Operations Radio Antenna Kit OE-452/PRC, AS-2259, etc.) rather than the vehicle mounted whip antennas (AT-1011, etc).  The AT-1011 when 32 feet high is too tall for vehicle use, but could easily be attached to a building.
  
• Antennas for use above 30 MHz (VHF and higher frequencies) work better the higher they are.  For example the OE-254 has more than twice the range when mounted at 30 feet than when mounted at 15 Feet.  A 2-1/2 story building can have up to 10 foot interior ceiling height and a 1/2 story must be less than 7 feet head room ( 6'-11-15/16").
  
• The S-250 electronic equipment shelter that's vehicle mounted is has outside dimensions of 89" (7.4') L x 73" (6') W x 73"H with the base narrowing to 49".  These can fit in full size pick-up trucks or a number of military vehicles. But they only have about 45 square feet of floor area and are rather cramped.  The S-280 electronic equipment shelter is larger at 147” ( 12-1/4') L x 87” (7-1/4') W x 86 3/8”H for an exterior size of 89 square feet.  A free standing 120 square foot building has more floor area and is much lower in cost.

180 Watt 24 V PV Module ET-M572180B

Max Power Point Tracking Charge Controller

6V Golf Cart Batteries (4 ea) 232 AH

http://www.interstatebatteries.com/cs_eStore/content/product_info/golf_f.asp

Battery Type	Volts	RC	RC	Ah	Dimensions			Weight	Terminals
		75A	25A	20 Hr.	L	W	H1	Wet (pounds)
GC2-XHD	6	122	475	232	10 1⁄4	7 1⁄8	11 1⁄8	67	UTL, UT, S

Battery Terminals

Load Center

http://www.midnitesolar.com/productPhoto.php?product_ID=122&productCatName=Box

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