Are You Practicing Safe Solar?

Often when people think about being safe around their solar system, they only

think about not dropping anything on or damaging the batteries. In this article we

are going to talk about the safety concerns and proper wiring for the entire solar

system, not just the batteries.

For starters, it is important to understand the total flow of electricity through the

system. Don’t check out now because it is technical – bear with me because this

is important. First, the solar modules send the power to the charge controller.

Next, the charge controller sends the power to the batteries. From there it goes

to the DC to AC inverter. Then it finally goes to the house outlets and switches

where it is used by the consumer.

Any one of these four major components in an off-grid system can fail, which

could cause a short in the system. If not properly protected from each other or

from outside influences such as lightning or accidental damage, any one of these

units could cause catastrophic system damage or even fire.

To protect the system from this happening, there are important steps to take to

be sure we not only protect each peace of equipment from damaging one

another, but most importantly, to protect ourselves from bodily harm or even

death. And yes, I know what you are thinking; he is using the word death just to

be dramatic. In fact, THAT IS NOT THE CASE. DC current at the levels a solar

system is generating from the charge controller to the batteries and especially

from the batteries to the inverter is actually much more dangerous then AC

voltage. Two of the major reasons are: First - Personal Safety - DC voltage

makes your muscles contract, which makes it very hard to let go of whatever you

grabbed in the first place. This means the shock will go on for a longer period of

time. This longer exposure can cause heart fibrillation and yes, even death.

Second – Equipment Safety – A high-current DC circuit is much harder to break

then an AC circuit. This means if you try to separate a large DC circuit without

the proper equipment, the chances of an Arc flash and fire are much higher than

with that same size circuit in AC.

So, to protect ourselves and our expensive solar equipment from damage, we

must be sure to have the proper breakers (or fuses) and lightning arrestors in the

proper locations. It should be noted here that all breakers are not created equal.

You cannot use a breaker purchased at a local hardware store to connect your

DC panels to your charge controller. Not only will they not work properly, they

can actually cause a bigger chance of fire and damage then nothing at all in

certain situations. Proper DC-rated breakers must be purchased from a solar

distributor.

Let’s re-list the basic solar system we started with using the correct sequence with

breakers added in: Solar modules, DC breaker and lighting arrestor, charge

controller, DC breaker, batteries, DC breaker, inverter, AC breaker, house main

panel. If all these circuits are properly installed and are the proper size, even if

the system gets hit by lightning or suffers from temporary user stupidity, the

likelihood of the entire system getting damaged is very low.

Hopefully this helps you understand the basics and importance of solar system

safety. If you have any questions about your own system’s safety, please give us

a call.