After we've used the System Builder to design our array to our liking, the next step is to add Mechanical & Electrical Balance of System (BOS) Components. Within the BOS wizard, we'll be able to specify:

The first page we'll be taken to after selecting this option is the Mounting System page. This page allows us to make specifications about our rail and mounting options, roof zone spans, grounding method and more. The blue "?" icons at the left of each option provide additional tool tips to help clarify what each selection is referring to. 

Note: The rail and mount options available will vary depending on what racking system you select in the System Builder.

One important data point to consider are the maximum rail spans. To find the appropriate span values for each roof zone, you'll need to refer to rail span tables or online configuration tools provided by the rail manufacturer.

Once we've made all of our selections, we can select Save and Continue at the bottom of the screen. 

The next page allows us to specify our electrical BOS components (e.g. a wiring strategy, interconnection method, rapid shutdown, combiners, disconnects, meters, etc.).

After specifying electrical components, click Save and Continue to continue to the Locations page.

Here, we can specify the location of various components, as well as roof access points. The legend at the top of the screen identifies what each marker indicates. SolarDesignTool will automatically calculate wire distances based on where the equipment is placed.

Note: SolarDesignTool automatically makes assumptions about where each component will be placed, but adjusting their position is as simple as dragging and dropping them in the desired position. Additionally, it's possible to disable a particular location by clicking the X marker on the right side of the screen. 

The next and final step in our BOS menu, is specifying wire and conduit options, such as conduit type, conduit run strategy, maximum wire temperature, and distances between components. 

Note: The tool will automatically attempt to come up with the distances between components, but this can be adjusted from this page, or from the conduit-conductor sizing tool.

After we select Save and Finish, we'll be taken back to the project page with a number of new document generation options available. Check out our PV Documents Guide for more information.