Solar panel support example – Johnson Level & Tool Mfg. RAS-1 User Manual

Page 36

TABLE B
Change Decimals to Fractions
.06" = 1/16"

.56" = 9/16"

.13" = 1/8"

.63" = 5/8"

.19" = 3/16"

.69" = 11/16"

.25" = 1/4"

.75" = 3/4"

.31" = 5/16"

.81" = 13/16"

.38" = 3/8"

.88" = 7/8"

.44" = 7/16"

.94" = 15/16"

.50" = 1/2"

SOLAR PANEL SUPPORT EXAMPLE

Let us build a rafter support for a series of flat plate

collectors on a south-facing 8-inch rise roof.
STEP 1. RAFTER CALCULATIONS: The pitch for the

support rafters, which is really the desired tilt angle for

the solar panels, will be needed. If known in degrees,

convert it to the nearest inch rise so that the tables may

be used. This pitch is found by adding 10 to 15 degrees

to your latitude (since this is theoretically the best for

heating). In our example, we need a 58° pitch or a 19

inch rise because the latitude of Milwaukee is 43°. (See

Table C, page 39). The angle of tilt is not critical, since

the efficiency is not appreciably reduced by a small dif-

ference in tilt angle from optimum, thus the closest inch

rise can be used (see Figures 20 and 21).