SOLAR POWER SYSTEM DESIGN
makezine.com/14/primer
A
Solar panel array
OutBack
PSPV
combiner
600V DC
30 amp
unfusible
disconnect
switch
OutBack Flexware
FX500 DC breaker
enclosure
OutBack MX60
MPPT charge
controller
OutBack Mate
remote monitor
and control
OutBack GVFX3524
3,500W 24V DC
120V AC inverter
Positive DC Wire
Negative DC Wire
Ground Wire
Hot AC Wire
Neutral AC Wire
Cat 5e Network Wire
Ground Rod
24-volt
battery
bank
OutBack Flexware
FX500 AC breaker
enclosure
Circuit Breaker
Utility line
Utility meter
30 amp AC
unfusible
disconnect
switch
DC Lightning Arrestor
AC Lightning Arrestor
Main AC load center
AC 120V
outlets
PLAN YOUR POWER NEEDS
First, identify your overall goal, obstacles, equipment
and hardware needs, equipment placement, and
solar panel array location.
There are 3 basic types of solar PV systems:
off-grid solar PV systems, grid-tied systems with no
battery backup, and grid-tied systems with battery
backup (which is the type I built).
Build It Solar ( builditsolar.com) is a great resource
for all 3 types of solar projects.
MATERIALS
My system mainly consists of OutBack Power Systems
equipment ( outbackpower.com), including the
inverter, breaker boxes, charge controller, and other
components. You can buy these components at
many different locations. A few online stores I recommend are Affordable Solar ( affordable-solar.com),
the Alternative Energy Store ( altenergystore.com),
and The Solar Biz ( thesolar.biz).
1. SOLAR PANEL ARRAY
Solar PV systems normally consist of multiple solar
panels connected together in series and/or parallel
to form a solar PV array (Figure A). A solar charge
controller protects the batteries by regulating the
current and voltage coming from the solar array; its
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specifications usually determine how the solar panels
must be configured. For instance, some charge
controllers only accept specific DC voltage inputs
of 12V or 24V. Therefore, you can connect two 12V
solar panels in series to create a 24V solar PV string.
You can then combine multiple 24V strings in parallel
and connect them to a PV combiner enclosure
(which takes the input from multiple solar panels
and combines them into one DC output).
Note that 24V is too low for certain system
designs, because when you increase the current
on a wire with only 24V, you decrease efficiency and
increase voltage loss. A larger-gauge wire would offset
power loss by reducing resistance, but the best
solution is to use a charge controller that accepts a
dynamic DC voltage and steps down the voltage to
charge the battery bank. Dynamic charge controllers like the OutBack MX60 enable you to stack
solar panels in series up to 150 VOC (open circuit
voltage). This configuration allows multiple solar
panel stacking options and saves money by reducing
the wire size needed.
2. PV COMBINER ENCLOSURE
The OutBack PSPV combiner box (Figures B and C)
combines multiple strings of solar panels together
in parallel to form a solar array. Each string of input
Illustration by Alison Kendall
