What if you could be producing more energy while installing fewer solar panels?

By Alexandre Gilbert-Vanasse, VP Business Development, Opsun

Developers and investors looking for ways to increase their return on investment should question the established model of installing as many solar panels as possible on a given roof and instead try to get the maximum power generation with as few solar panels as necessary. .

Solar optimization is the new buzzword for solar energy on flat roofs. In the past, flat roof commercial solar systems such as 5 degree tilt and east-west (A-shape) systems were common, under the assumption that more power meant a better system. The truth is that what really counts for owners and investors is how many kWh the system will produce over its lifetime. “Solar Optimization” means striving to obtain the maximum amount of usable electricity for each panel installed, over 20+ years.

In the past, increasing the return on investment of a solar installation was done by reducing the installation costs (in $/W) and increasing the size of the systems (Watt rating) as much as possible. This has been the simple, standard way of presenting solar projects for the past decades. But this model was shaken when large utility-scale ground-mounted solar systems began to appear on single-axis trackers. The capex of trackers may certainly be higher than fixed-tilt systems, but the extra 20%+ energy yield convinced developers and investors to change their paradigms.

The same is happening with commercial flat roofs and bifacial solar panels: by leveraging the efficiency of rear bifacial solar panels and increasing the inclination angle and height of the array from the roof, an additional 8% to 20% of energy can be harvested from an optimized installation of two-sided solar panels, versus the same roof with monofacial panels. Since the rear of the solar panel is completely free of rails or wind deflectors, as is the case for example with Opsun Sunrail SR3 bifacial racks.

As the sun travels through the sky, some of the diffuse light bouncing off clouds and surrounding structures is reflected on the roof membrane and reaches the solar panels from behind. It acts as a passive tracker, flattening the production curve and increasing the maximum output power (as limited by the inverters which must have a lower DC-to-AC ratio).

Why optimize?

By optimizing a rooftop solar system, owners benefit from more usable or salable electricity per panel installed, reduced installation time and costs, while reducing the number of panels to maintain in the long run. The result is lower initial costs, lower O&M costs and higher revenues.

The reason that ground-mounted systems are usually set at about 30° is that this is optimal for solar panels, as they capture more light and cool better at greater angles of inclination. Why limit flat roof systems to just 5°? With regard to ground-mounted solar systems, optimization on flat roofs means greater tilt angle, height and spacing, each of which will improve the performance of the individual panels.

Just like a sports car, several details must be tweaked for a solar system to perform, and owners and investors will benefit from a powerful system. It’s not just about having the biggest motor (kilowatt peak), it’s about optimizing every part to produce more electricity (kWh)!

The difficulty lies in comparing the return on investment of a 10° tilting monofacial versus a 10° or even 15° tilting bifacial system. It is not an easy task and it can be quite time consuming, which explains that often only 5° or 10° is evaluated.

The tool: the opsunizer

Opsun offers an online tool called Opsunizer that allows developers, building owners and investors to quickly and easily build different solar systems and compare their production and ROI on a given roof. A quick design and comparison of, for example, a monofacial versus a bifacial solar system with the same footprint can be made in a few clicks. The Opsunizer unlocks a toolset useful to developers who want to create and build an optimized bifacial solar system with high energy production.

For example, owners of buildings with white TPO or EPDM roofs can log into the platform, find their building, quickly fill the roof with solar panels and compare different designs, each leading to different electricity productions and a different return on investment.

Within minutes, a solar system can be optimized and an ideal, cost-benefit solution determined. This will help owners guide the development of solar projects in the first steps. As a commercial partner and rack manufacturer, Opsun can then assist during the engineering phase by supporting the optimization of all components of the entire solar system.

In an era where solar power goes hand in hand with reducing pollution and waste, it should be a concern for all conscientious solar project designers.

Try the Opsunizer tool here

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