Solar Panel Arrays
Serial or parallel interconnections in solar panels are called
solar panel arrays (SPAs). Generally, a series of solar panel arrays
are configured to produce a specific voltage potential and
collective power production capacity to meet the demand requirements
of a project.
Solar panel arrays feature a series of interconnected positive (+)
and negative (–) outputs of solar panels in a serial or parallel
arrangement that provides a required dc voltage to an inverter.
Figure 1.6 Shows the internal wiring of a solar power cell. The
average daily output of solar power systems is entirely dependent on
the amount of exposure to sunlight. This
exposure is dependent on the following factors. An accurate north-south orientation of solar panels (facing the sun), as referenced earlier, has a significant effect on the efficiency of power output. Even slight shadowing will affect a module’s daily output. Other natural phenomena that affect solar production include diurnal variations (due to the rotation of Earth about its axis), seasonal variation (due to the tilt of Earth’s axis), annual variation (due to the elliptical orbit of Earth around the sun), solar flares, solar sunspots, atmospheric pollution, dust, and haze. Figure 1.7 depicts a photovoltaic panel module assembly mounted on a galvanized Unistrut channel.
Photovoltaic solar array installation in the vicinity of trees and elevated
structures, which may cast a shadow on the panels, should be avoided. The
geographic location of the project site and seasonal changes are also
significant factors that must be taken into consideration.
In order to account for the average daily solar exposure time, design
engineers refer to world sunlight exposure maps. Each area is assigned an
“area exposure time factor,” which depending on the location may vary from 2
to 6 hours. A typical example for calculating daily watt-hours (Wh) for a
solar panel array consisting of 10 modules with a power rating of 75 W in an
area located with a multiplier of 5 will be (10 × 75 W) × 5 h = 3750 Wh of
average daily power.