2.1-- site visit - etm solar works site...october 2012 pv installer’s course: the site visit 3 the...

PV Installer’s Course: The Site VisitOctober 2012

2.1--The Site Visit

Gay E. Canough

1


Site Survey KitChecklist100’ tape measure, 25’ tape measuresolar pathfinder, compasscameranotepad and penladderflashlight, flathead screwdrivermagnetic protractor

2


The Site VisitFind a place where there is no shade from 9 A to 4 P. No shade is guaranteed when the object is 3 times as far away as it is tall. The roof is the best place unless it is shaded. Try to keep ground-mounts within 100 feet of house

Shade problem


Site Measurements

The Site Visit


Measure roof up-slope

The Site VisitOld shingles: 5” per rowNew Shingles: 5.5” per row


Up-slope dimension cross check: measure slope, do trig

hypotenuse

angle

The Site Visit


Trig review

Opposite (Y)

Adjacent (X)Angle A

Tangent A = opposite / adjacentSine A = opposite / hypotenuseCosine A = adjacent / hypotenuseAngle B = Angle A (Rule of Similar Angles)

Hypotenuse (H)B


The Site Visit

Look in the attic, measure rafter spacing and size


The Site VisitWhat kind of roof supportIs there?


The Site VisitWhere is the meter? The incoming utility lines? (If any)

“Site Plan”


If you have to do tilt-ups on roof, space the rows so one does not shade another.


Tangent(18) = opposite over adjacent = Y/X = 24”/X Solve for X

X = 24”/tan(18) = 73.46” = 6 feet

If you are unfamiliar with algebra, make a scale drawing instead.You will need a ruler, protractor and calculator to do this.


Tilt-up on NW roof to face PV South


If you do multiple pole-mounts, place poles so one PV array does not shade the otherSun-angle


Pole-top PV mount


Choose a place for the battery bank. Batteries like to be warm The inverter must be within 20 ft of the battery

Measure the distance from that spot to the battery location

The Site Visit


Choose a place for the inverter and disconnects

Battery boxPower panel

vent


Record the size and type of cabin circuit box (load center) If there is no circuit box, make a note of that and record the number of circuits (or potential number)

The Site Visit

Sum of the Main breaker and PV breaker must be less than or equal to 1.2 x bus bar rating

Example: 200 A main on 200 A bus bar means that 200 + breaker fed by PV system has to be ≤ 1.2 x 200 or ≤ 240. So the largest PV breaker is 40 A

2.1-- site visit - etm solar works site...october 2012 pv installer’s course: the site visit 3 the...

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