What is Balance of System and Why is it Important?

By May 20, 2021June 10th, 2021No Comments

When purchasing a solar power system, most buyers tend to focus heavily on the panels themselves, and for good reason. They are the main component of the system itself. But, most are also surprised to find the associated costs of components that go into ensuring the panels work as they should.

All solar panels are supported by a balance of systems (BoS) that includes a plethora of hardware that support and deliver the electricity from the panels to your home. The BoS needs to be considered for a number of important reasons.

The BoS accounts for 10%-50% of the total cost of a solar power system and the majority of the following maintenance costs. BoS is where most installers try to create financially attractive offers for consumers. They either do so by ordering large quantities of bundled BoS from single suppliers, or, by sourcing each component separately.

Unfortunately, since most consumers are not conscientious of the importance of BoS, they may end up with poorly made systems. A bad quality BoS can affect your panels output, and even cause damage to your property

So, here are the main components of a solar panel BoS and what they do.

Solar Panel Mounts

The mounts are what attach the panels to either your roof, or support them on the ground. Two types of mounts are typically used with PV panels –


These are typically used for residential or commercial installations where roof space isn’t an issue. Roof mounts come in three varieties –

  • Ballasted mounts: Ballasts are weights that hold the solar panels down to the roof. An installer will often prefer them as they negate the need to have the panels bolted into the roof. However they will only work in low wind areas, and for large systems.
  • Mechanically attached mounts: These use posts and roof beams to keep a solar panel system secured in a place. These mounts require leak protection since your installer will need to drill them into your roof.
  • Hybrid mounts: Uses both ballasted and mechanical mounts to create a stable foundation without needing to penetrate the roof.

Ground-mounted Solar Panels:

  • Low profile mounts: These are a simple and cheap to install solar mounting system. The solar panel footprint here can be as low as 30 inches.
  • Pole mounts: These solar panel mounts are seasonably adjustable, while maintaining a low footprint.
  • Ballasted footing mounts: These use concrete or steel bases which use weights to keep the solar panels tethered to a place. Like roof mounted systems, these do not require any ground penetration so they are ideal for sites where excavation is not possible.
  • Foundation mounts: These solar panel mounts use concrete slabs or poured footings to keep the solar panels fixed in place.

Electrical Components

A plethora of wires and switches go into connecting your solar panels to other components. Solar PV systems for instance do not use regular wiring. Specially made solar wires that are designed to be both UV and weather/wear resistant are used in PV systems.

Wiring is usually measured in either B&S (Brown and Sharps) which is similar to AWG (American Wire Gauge) standards. So a 6 B&S gauge is similar to 6 AWG in thickness. Much like shotgun calibers, the lower a gauge is, the thicker the wire.

Here’s a quick rundown on the types of wires and where they’re used –

Since a wire gauge depends upon the system size and how much distance the wire must be laid, your installer will decide which one to go with. Even so, it’s best to educate yourself here. The total wiring required can sometimes end up costing as much as a solar inverter. So, many installers tend to go with thinner, low quality wires to make ends meet (pun intended).


Solar panels produce DC (Direct Current) electricity which is unusable in its raw form. DC electricity only flows in one direction and usually has one constant voltage value. House appliances on the other hand, require two-way flowing AC power. The voltage of AC electricity can be changed, depending on requirement, making it ideal for home use. Inverters convert the DC electricity from your panels into usable AC power.

While regular inverters may seem sufficient for a solar PV system, they lack some critical capabilities that are available in specially designed solar inverters. We’ve covered this in greater depth in our article on solar inverters, so do check it out.

Don’t Go In Blind!

All things considered, deciding on the right solar panels for your home is actually easy. The tricky part is ensuring your system has an optimally designed BoS supporting it. Since many installers may cut corners when designing your BoS, it’s vital you have a good understanding of what to ask and expect.

Having helped hundreds of customers find the right solar power system for their homes, we at bidmysolarTM are confident we can help you do the same. Our rigorous screening process ensures only the best CEC accredited installers bid on your project.

Interested in learning more about how we work? Check out how we work, or give us a call if you’d like to learn more.