Hickam Airforce Base Goes Solar--147 kW photovoltaic system

Hickam A/F Base Photovoltaic System:  After the cool ply is cured and secured, three evergreen 200 W. photo voltaic panels were mounted.

Strut Spacing and Pricing

Solar strut provides the foundation between the roof and solar array.  It is important to first draw and chalk out the layout then proceed to rafters.  Most homes are either built with a 16 ir 24 " distance between the two rafters.  Most spacing is done by using every other rafter or a 32 to 48 inch span.  This distance provides support for the array without comprimising and windload issues.  Solar strut is expensive and should be used prudently.  I learned this the hard way.  I was overy concerned with the wind loads so I spaced the strut every 24 inches and it cost an extra 1000 dollars.  I nearly lost my job, but rather took a pay cut. 

In the end, solar strut provides  a solid bond between the  roof with the array, but can put a damper on costs. 

Hickam Airforce Base 147 kW Project

21st Century Technologies has begun a project on Hickam Airforce Base that is considered the largest armed forces installation in Hawaii.  After getting all of the roof materials to the project, we started the layout for 120 Evergreen panels that will be mounted to cool ply.  This new innovative roofing material has three mainfunctions.

1.  Provides strong material for historical roofs
2.  A cement called MBR is mixed attaches the cool ply to the roof.
3.  Two comprails are attached to the top part of the cool ply. 

The cool ply dimensions are 135.5 x 57.50 inches.  The panels are slightly longer than the width of the cool ply.  The layout must consider the difference between cool ply and panel.  We were able to fit 140 cool ply on the roof. 

Hidden Wires in Rafters, Beams, or Eaves!

There are times when an electrician will hide wires within the beams or rafters for a few reasons.  An open beam home will not have the options of hidding wires in the attic space, and consequently hide them inside the beams or on the side.  This can be a severe issue without the help of the homeowner, builder, or building plans.  It is imperitive to locate the wires in the beam before any penetration. 

A two man team with cellphones are crucial.  One man will find the wires, measure them from the eave to the wire and relay.  The roofer will mark the no zones on the roof and evaluate layout for pins.  Most likely the layout will be slightly different, but will not hinder structural untegrity.  A roof-bolt can not be more than four feet away. 

Labeling and Mapping is Key to Avoiding Possible Problems

A typical residential installation has many individual parts that can be hectic without proper labels and mapping.  Our crews will label the the roof with panel location, comprail location, and strut location before roof penetration.  This procedure gives us definite awareness as to how and where the system will be located.  This step is important because panels are secured on comprail, comprail is attached to strut, and strut is secured on to roof bolts. 

After a drawing is done, located rafters and use a chalk line to find the center and mark them.  Use the line to space out the achors by dividing the length of array minus 6 " x 2 (use for both side of over  hang).  For example, solarworld length is 66 " with two rows, 66 x 2 + 1 1/4 " for comprail on the ends and 3" - 11/4 for the middle comprail.  I ussually add 1 inch  for the end of one side.  Also,  one piece of the strut is longer for the J-box to attach to. As you can visualize, this process is complicated and a design/map will imperitive to successful roof mounting.

Mapping the inverters for EMU communication is necessary.  Use the enphase map to located all the inverters.  Make sure the barcode is attached to the map.  This will allow the owner to verify panel and inverter production.  Also, write on the inverter the location and string.  This is a must to aviod confusion for mapping the location of panel/inverter in the array.

The picture below is an exellent example of how complicated the process can be.  The inverters are mapped and mountd on the comprail, the strut is down and secured with one a little longer for the j-box.  The panels are place with in the comprail and secured.   

Hawaii Kai _Saeki Job done

This roof's dimensions were a  25 ft x 15 feet.  We fit fifteen Sunworld panels with fifteen enphase 190 inverters with plenty of room to spare. This roof is secure and generating around 18 kWh per day.  Awesome!!!!  Enjoy

ENPHASE 190 WIRED IN SERIES

Two strings of Enphase 190 Inverters tied in with Sunworld 230 Watt panels.  Every string will have a end butt and a group of four wires.  This system had fifteen panels with inverters.