Smart energy harvesting performance of photovoltaic roof assemblies in Canadian climate

ABSTRACT In Canada, the solar electricity sector is growing rapidly. Much of this success is based on the growth of the Ontario solar market where more than 99% of Canada’s solar electricity is generated. Ontario has developed a globally recognized solar market sector. The vast surface area of existing residential roofs across Canada represents an untapped resource for capitalizing on passive and active management of impinging solar insolation. The aim of the current research study is to evaluate the new energy harvesting technologies such as a thin-film PV integrated roof system that could serve as a conventional roofing for weather protection while generating clean solar electricity, and the new generation micro inverters that have the potential to outperform string inverters under shading and snow-cover conditions. This paper has two parts that will discuss about two smart energy harvesting technologies and their performance on residential applications in Canadian climate. Part 1 of the paper focusses on field evaluation of Roof Integrated Photovoltaic (RIPV) and Part 2 talks about the energy yield performance of integrated solar tiles and new generation micro inverters. The RIPV field trial took place at the Canadian Centre for Housing Technology (CCHT) Info Centre in Ottawa, Canada. This is a novel approach adapted from a roofing system that would typically be found on low-sloped roofs such as commercial supermarkets, industrial warehouses and school buildings. Over the eight month study period, surmounting the effects of snow cover and shadows, the RIPV system generated over 1 MWh of electricity, and had a measured system efficiency of 5.3%. The study on the new generation micro inverters for residential applications addressed the shading effects on the intermittent nature of solar energy generation. Simulating the shading conditions that are experienced by typical residential rooftop, the micro inverters were found to increase production by 1–68% relative to the conventional string inverters. The research outcome of this study has demonstrated that both these energy harvesting technologies have important incremental benefits in increasing the renewables contribution to power generation in residential homes in Canadian climatic conditions.