It’s tempting to pack a roof with too many solar panels to sell a system, says Randy Batchelor, instructor, along with Ryan Mayfield, of HeatSpring’s Megawatt Design course.

“An engineer might say, ‘It will only fit 1 MW.’ A salesperson might say, ‘Let’s fit more on to win the deal.’”  

It’s important to strike a balance between being too aggressive and too conservative when designing a solar project.

You May Win the Deal Being Aggressive, But May Have to Cut Project Size

“If you’re aggressive and set high expectations for the client, you may win the deal,” Batchelor says. But designers and contractors may then face headaches. “You may find structural issues or other issues that require you to cut back the system size. Unknowns almost always cut back the system size.”

For example, if there’s a huge roof, and designers don’t have exact dimensions or know anything about the roof, they should do a layout and avoid designing for too many solar modules.

“Do I want to try another layer of modules? There may be obstructions,” Batchelor says. “You can cram as many modules that will fit or back off a little. I won’t cram extra modules into all the corners. I’ll square it up and make it consistent,” he says. 

It’s important to leave room for inverters, conduit and fire setbacks.

“Sometimes I see roofs packed with modules, but there’s not enough setback for fire safety,” he says.

Provide More Space on the Roof Than You Need

The most basic rule of thumb is to provide more space than you need. Be sure to include pathways for setback and access to solar panels. “If you’re not sure about dimensions, be conservative,” he advises.

Batchelor and Mayfield provide this type of advice to the students in their course, who are generally individuals with residential solar experience who want to learn how to implement bigger projects. They are also commercial companies scaling up and doing bigger projects. Students also include large companies, government employees and utilities.

Commercial Projects are Booming

Batchelor notes that the commercial solar industry has boomed over the past 10 years or so, after lagging behind residential and utility scale solar.

“The dollars are there to drive projects, and so is the size,” he says.

But commercial and industrial projects–those discussed in his class–require engineering and technical skills. “It creates a higher bar for getting these projects done,” he says.

Residential projects are more straightforward, he notes. 

“Scaling a company to execute on commercial and industrial is more challenging,” he says. It’s difficult, he says, do to 100 1-MW projects in a year. It’s easier to do many 10-kW projects, he adds.

“Residential projects are more cookie cutter and more straightforward from a financing perspective,” he says.

How do You Learn to Strike a Balance?

With the growth in larger projects, it’s even more important for designers to take the time to strike a balance between packed roofs and conservative designs that will reap fewer headaches.

“Everyone makes more money and gets better returns with bigger projects. But you have to  resist the temptation to be too aggressive,” Batchelor advises.

And how does a designer learn how to do that?

“Understanding that balance requires a lot of experience or a good class,” he says.