[RE-wrenches] Multi faced car talk puzzler cabin

[Dana]

Ok here is the puzzler-

 

A Mountain cabin on the north side of a mountain & 5 hours of 400 watts of
PV would run the place 12 months of the year. 24 VDC system & minimalist
load schedule.

We cannot mount on the roof as it gets to 4-5' deep and slides all at once
in spring and would shear off anything up there.

 

South side Upper portion of south wall gets winter sun for 2.5 hours. Lower
portion summer sun only and upper may get some shade from overhang of
soffit. There is an assortment of windows on south side.

 

West side actually gets 2.5 hours of sun on an indirect angle due to how the
mountain and valley open up to the west; it is hard to match a tangent sun
angle without some very creative angling and interference with a couple of
scraggly old spruce trees. 

I would cut them down as they look disturbed from the construction and the
roof sheds 4-5' of snow all at once in the spring melt off and this may take
them out anyway.

 

Client wants to not obstruct the windows and the views & to mount [5] pairs
of 200 watt used [same make & model] modules he has collected from a grid
tie system that got run over by a center pivot irrigation system. Please do
not ask it was not mine.

On the south side [1] pair would be in landscape and [2] pairs in portrait
stacked one set above the other. The lower set would see summer sun the
upper pair would get shaded.

All 5 pairs will never see the sun at once. Actually 3 pairs might see sun
at any given time, maybe at some point in the the year.

 

I speced: [1] Outback FM80 CC & Outback Eng said if we use the FM80 [has
enough wattage capacity at 24 volt to handle this collection] that it will
operate at the low end of its MPPT range to accommodate the shaded modules
not the ones in full sun.

 

Do I use 5 separate charge controllers to deal with in actuality 5 separate
arrays? Or [2] charge controllers - South wall and west wall or live with an
oversized array that operates at the low end of its MPPT range? 

 

None of the choices are great; the house was built with a hydro system in
mind till he found out that the water stops running once it freezes [opps].

 

Fellow solar puzzlers - How would you do this?

 

 

Dana Orzel - Great Solar Works, Inc -  E - dana at solarwork.com -  V
970.626.5253

F - 970.626.4140     C - 970.209.4076     web - www.solarwork.com  

"Responsible Technologies for Responsible People since 1988"

Please consider the environment before printing this email   NABCEP #
051112-136

 

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