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Canadian researchers have developed a freely accessible online tool that reportedly helps homeowners achieve significant savings when installing rooftop photovoltaic systems. The tool is claimed to offer accurate structural engineering calculations while ensuring compliance with building codes.
Researchers at Western University in Canada have created an open-source online tool to streamline the engineering analysis process for implementing a rooftop photovoltaic system.
“The tool could easily be adapted to other countries,” lead research author Joshua M. Pearce tells pv magazine . “Snow loads in Canada and the regulatory environment in Ontario generally make it stricter to follow Canadian guidelines than elsewhere. Unfortunately, right now in Ontario, with homes with tiny solar systems, homeowners can spend more on the engineering analysis of their roof than on the solar panels. The main problem is that we are paying for the engineering analysis for each and every home individually. This is redundant, meaning that the analysis for an identical roof is the same. It is incredibly wasteful to have this done for every home.”
According to Pearce, the unique feature of the new online framework is its ability to speed up the engineering analysis process. “It would make a lot of sense for any government that wanted to encourage distributed rooftop solar to follow our lead and perform the analysis for all the most common roof types in their region, in order to streamline the process and massively reduce costs for everyone. Additionally, all homes should include the structural analysis for a solar-ready home as part of the baseline structural analysis that is done for rooftops anyway.”
In the study, “ Streamlining structural engineering compliance of rooftop solar photovoltaic installations using an open-source approach,” published in Solar Energy , Pearce and colleagues explain that engineering analysis for rooftop PV systems in Canada ranges in cost from $900 to $5,000, depending on the location and complexity of the project.
Using the proposed tool, its creators say, could enable Canadian homeowners to achieve savings of 72% to 1,600% for plug-in PV systems and 2% to 167% for installations requiring a professional installer. “Even in the much larger US market this tool can be useful,” they said, noting that the total capital cost of a residential system project could be reduced by up to 25%.
The tool requires users to create three documents to be eligible for rooftop installation: a PV Roof Design Form; a Truss Description and Analysis Form; and a Questionnaire Form. Users must also add images to validate the information provided on the forms. “While the images do not provide any scientific value, they do provide the information needed to verify that the claims on the forms are correct,” the academics specify. “The package is then sent to local authorities, such as a city or municipal official, depending on the jurisdiction.”
The online tool is set up as a spreadsheet that includes input parameters such as material properties, roof dimensions, and design loads. A minimum of five photos must be submitted with the three forms to a local authority, which researchers say would automatically eliminate the process of hiring a structural engineer. These procedures reportedly provide “accurate” structural engineering calculations while ensuring compliance with building codes.
The research team also presented a case study for a typical homeowner looking to install a 5kW PV system located in Michigan, USA. System costs were estimated at $15,450 and additional engineering fees at around $3,000, with the project having secured a 15-year loan and the home located in an area with below-average electricity costs and below-average solar radiation.
“Using the open source tool provided in this manuscript, the homeowners would have paid off their system in 13 years, whereas without it the payback period is extended to 16 years,” the scientists explain. “As the payback period is extended beyond the loan term, this system would simply not be installed without the open source tool because the homeowners could not afford the additional costs of engineering fees.” |
