Optimizing for Speed in Commercial Rooftop Applications

All the focus and pressure to realize high yields and low costs on an individual project often blinds companies to the benefits of a fast execution and in some cases can really slow things down.

When solar designers think about optimizing a PV system, they typically think of ways they can modify various design parameters to save costs and increase energy production. While these are certainly worthy goals, optimization also includes having the ability to design and build projects with speed. Designers should not lose sight of opportunities to optimize projects by reducing costs and improving the client’s return on investment (ROI). However, optimization is also about reaching your company’s financial goals and getting more megawatts on the ground. Optimizing your company for profitability and continued growth is ultimately what will help the climate and create more solar jobs.

While some of the suggestions presented here may seem counter to traditional thinking about project optimization, optimizing for speed can definitely have benefits at the project level. Accelerating system design and construction can reduce engineering and labor costs. Moreover, the sooner a PV system starts generating energy, the sooner the client starts saving money. Most important, a shorter project life cycle increases the number of projects a company can build with the same number of employees, reducing soft costs and overhead as well as enabling faster growth.

Establish Goals and Priorities

It is difficult to optimize a system design without having clear goals and priorities. Does your client value ROI, reduced up-front costs, or long-term reliability and low maintenance costs? Of course, customers want all of these options, but clearly defining their project priorities will help you identify a preferred design approach.

Company goals are also important. One solar contractor might be focused on hitting annual profitability goals, while another is willing to cut margins to increase market share. These are not just issues for management or project estimators. These different company priorities affect design and construction decisions.

When a company’s sales, engineering and construction teams are all on the same page with regard to the priorities of both the customer and the company, it gives everyone involved the confidence necessary to make decisions quickly.

Invest in Site Evaluation

One of the best ways to accelerate a project schedule and reduce risks is to invest in a thorough site investigation, in some cases even prior to signing the contract. Site investigation is not an area where you should be looking to save money. While there are significant costs associated with more-detailed site evaluation activities—such as a professional survey, electrical evaluation, structural review or underground utility locating service—that initial investment provides a hefty return when you avoid expensive mistakes or wasting time on a system redesign.

Every project should have a detailed schedule outlined in project management software with clear dependencies. This schedule should account for and accommodate site investigation and design activities. If the project managers who typically control the schedule focus too narrowly on construction activities, a Gantt chart may not have adequate detail early in the schedule. Projects often get hung up when issues come up during site investigation. You can keep things moving forward by having a Gannt chart that shows early-stage project dependencies, as this can identify areas where you can accelerate the schedule.

Set Realistic Expectations

Solar contractors must set realistic expectations, both within the company and with outside stakeholders. This is perhaps most evident in the desire to maximize system capacity during the design process. As project capacity increases, the cost per installed watt generally goes down due to the dilution of fixed costs that are independent of system size. Moreover, the client wants to save as much money as possible, while the contractor wants to increase revenue. These factors greatly incentivize installation contractors to put as many watts on the roof as they can to win the deal and theoretically make more money.

Since roof area—rather than ampacity limits or load—often limits commercial rooftop system capacity, it is tempting to cram the maximum number of modules onto the rooftop. That leaves very little wiggle room for locating rooftop electrical equipment, establishing fire pathways and setbacks, or adjusting the array to account for unforeseen obstructions. If the sales team does not provide enough contingency space in the preliminary design, then problems can arise when something does not work exactly as laid out in the proposal—a common occurrence. You risk not only spending more time and resources correcting the issue and resetting customer expectations, but also incurring unanticipated costs as you try to satisfy those unrealistic expectations.

Such expectations can undermine project optimization goals in several ways. To meet inflated kWh targets, the design team may have to utilize roof areas where the solar resource is suboptimal due to shading, locate modules in roof areas subject to higher wind loads that require additional ballast materials or roof attachments, or add a small subarray on another roof area or even a different building. While each of these design responses will increase production, the cost per kWh will also increase.

Similarly, if the initial proposal overestimates project ROI or underestimates costs, the sales team will set unrealistic expectations internally in terms of project profitability and margins. Management may then apply pressure on the project team to drive down costs. As a result, the project team has to spend a great deal of time analyzing alternative design options, which can slow the project and increase soft costs.

Article Discussion

Related Articles