Just a few years ago, NREL released a report with suggestions for reducing the cost of residential and commercial solar. One of the recommendations was for software developers to create design tools that integrate site assessment, shading analysis, system design, and financial appraisal into one easy-to-use package. A handful of companies heard the message and got to work. One of them is Aurora Solar, whose cloud-based Aurora solar design and sales software,  which includes the SmartRoof design package, does all of the above and then some. I recently spoke with Aurora's Rahul Nihalani, Gwen Brown, and Mike Leith, who gave me an overview of Aurora's features and a demonstration of the software in action. If your company designs residential or commercial photovoltaic systems, you may want to check out this software.

Aurora Features

Aurora allows a designer to:

• Create a software model of the installation site

• Examine the customer's electric load profile

• Perform a shading analysis

• Design a PV system

• Simulate its performance

• Assure compliance with all codes and standards

• Identify potential sources of power loss

• Compare financing options

• Write a proposal

• Create physical layout and electrical wiring diagrams

• Develop reports for rebate and permitting authorities

Site Assessment

A system designer begins by selecting the site's location. In most cases, the user simply enters an address, and the software accesses Google Earth to get an overhead view. If Google Earth data isn't available, one can upload aerial images taken from a drone or other aircraft. If no aerial data exists, the software will accept blueprints of roof plans.

Once the building is identified, the designer selects all right-angles on the roof. With that, the system figures out all of the roof properties. It's about 95% accurate; users can easily touch up the details.

When available, Aurora uses LiDAR data to conduct its shading analysis. When LiDAR is not available, it uses satellite imagery. Aurora asked the National Renewable Energy Laboratory (NREL) to conduct a blind study of its shading analysis tool; NREL found that the software was accurate to within a 3% tolerance when using LiDAR information, and just under 5% tolerance when relying on satellite data. (By comparison, an on-site shading analysis using a product like the SunEye has a tolerance of about 5%.)

Based on the address, the customer's energy profile is obtained through the local utility. Some power companies provide detailed usage data, while others only report total monthly energy consumption; SmartRoof uses whatever information the utility provides to create the usage profile. Intuitively, one would design a system that maximizes energy production, which makes sense if the utility rates are flat (i.e., they charge a certain amount of money per kWh of energy used). However, with time-of-day pricing, where a customer is charged a higher rate during peak demand hours, it's more desirable to design the array to produce more electricity in the late afternoon and early evening rather than focusing on overall energy production. Given that both pricing structures exist, SmartRoof allows designers to maximize either energy production or cost savings.

System Design and Simulation

At this point, SmartRoof knows everything it needs to know about the site, so it's time for the engineer to make a few choices. The software has a database with tens of thousands of panels, inverters, microinverters, and optimizers. If the desired hardware isn't in the database, the designer can request that it be added, or she can upload the specifications of the device.

After choosing the hardware, panel orientation, and tracking options, the user selects the "fill zone" - the part of the roof that will be covered in PV panels. The software will figure out how to fit as many panels as possible into that area, taking into account panel size, tilt angle, inter-row spacing, roof obstacles, walkways, and access points.

SmartRoof then makes the physical and wiring layout and checks all parameters for code compliance. The engineer can request many designs for the same project and compare the results of each, using the software's simulation tool. (NREL evaluated Aurora's simulator and found its accuracy to be on par with established PV system simulators.)

In addition to providing performance data, SmartRoof also conducts a loss analysis:

Financial Assessment

With the system design completed, Aurora evaluates multiple financing options, including cash, loan, lease, and power purchase agreements. The software takes into account federal, state, and local rebates and incentives, interest rates, and projected utility bill savings, then calculates total cost, payback period, and return on investment. Aurora Solar says that all of the financing and regulatory agencies (those dealing with government rebates) accept Aurora reports.

Time is Money

As a web-based subscription service, Aurora users pay $159/month for the basic version or $259/month for the premium version. The monthly fee doesn't require a long-term contract, but users can get a discount by purchasing an annual subscription. Is the software worth the price? NREL estimates that a typical PV design costs about $170, not including overhead such as financial analysis, proposal writing, and regulatory paperwork. Manually, that's close to seven hours of work; a designer working with Aurora can do the whole thing in about an hour. For a company that bids on several systems per month, the product is likely to pay for itself within the first two or three designs.

Cost of design isn't a major factor in most PV systems, but a semi-automated tool like Aurora can reduce errors and produce optimized systems by allowing designers to quickly compare multiple options. Completing a design "from scratch" may take a few hours, making it unlikely that an engineer will evaluate a variety of strategies. With automated design software, a designer can evaluate several approaches in less time. That's better for the customer, the companies, and the solar industry as a whole.

Images courtesy of Aurora Solar

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