How Should I Wire Solar Panels to my Cutting Edge Power Solar Generator? (Series or Parallel?)

This is a common question that we get all the time. 

The simple answer:

When connecting solar panels to our solar generators, you can never go wrong by wiring your panels in parallel (++ --)

The long answer:

First we can go over some theoretical advantages and disadvantages of both.

Parallel:

• Best for beginners when dealing with solar power and wind power.
• Allows wiring to remain at a safe, low voltage. Typically we consider anything under about 30V DC to be “safe”.  Of course all electricity should be respected but the risk of getting hurt is lower when your voltage is under 30V.
• Requires larger gauge wiring due to low voltage, which can get expensive
• Requires longer “parallel” runs of wire which can be costly and labor intensive
• Less risk of damaging components due to lower voltage
• Generally more compatible with mainstream components

Series:

• For advanced users that are familiar with Ohm’s Law (see below)
• May be less safe when the resultant voltage is over 30V DC. 30V DC is widely regarded as the point at which you will be able to be shocked at a dangerous level.  Especially high voltages (60+ V DC) can be even more dangerous.
• Can save time and money by consolidating all wiring into one single circuit (basically one wire for all panels)
• Higher risk of damaging components. Generally as a rule of thumb, components that can withstand higher voltages are more expensive.
• Can be a huge advantage because you can use smaller gauge wire. An easy way to calculate this is with Ohm’s law
  • Power (P) = Voltage (V) x Current (A)

For example,

 (4) 100W solar panels with a V_OC (Open Circuit Voltage) of 18V DC, all wired in parallel will result in a final V_OC of 18V, final power output of 400W (4 x 100) and final current output of 22.22 Amps (400/18).

(4) 100W solar panels with a V_OC (Open Circuit Voltage) of 18V DC, all wired in series will result in a final V_OC of 72V, final power output of 400W (4 x 100) and final current output of 5.56 Amps (400/72).

Now, notice the Amps in the above examples.  The amount of current (Amps) is what dictates the wire size you’ll be required to use in your installation.  Less current = smaller wire.

Now that you understand the difference between series and parallel, you understand that there really isn’t just one bottom-line answer.  It isn’t so black and white.  This is why we have developed products for both situations.  The table below shows the maximum input voltage for our solar generators so you can decide which one is best for you based on your solar panel V_OC and how you plan to wire them.

Expert level:

The world of solar power is very deep and interesting and combining series with parallel can be extremely fun.  Experimenting with different series-parallel combinations can result in power increases and better reliability, but, we’ll save the details for another blog!