Techno-economic evaluation of a residential roof-mounted solar system

In this chapter, a case study is presented where a residential solar system in Kitchener, Ontario, is analyzed economically as its annual performance is also assessed. The recorded data for this system are investigated further to better assess its technical performance. This system is part of a government-incentive program called microFIT, which allows for generated electricity from renewable sources to feed to the local grid for generous rates ranging between $0.29 and $0.97 per kWh. The system is further examined to show the correlation between climatic parameters such as wind speed and temperature on the overall system performance. Wind speed shows an inverse relationship to the energy output, while the temperature shows a linear relationship. Optimal annual performance is observed when the temperature is at 18 °C and when the wind speed is at 3.8 m/s. Furthermore, using the System Advisor Model (SAM) developed by NERL, a residential solar system has been simulated with the addition of a battery storage in order to understand its impact on the performance and economic aspect of the system. The modeled system without the battery correlates closely with the actual installed system. In fact, the actual ROI for the system is 19.75% while the modeled ROI is 23.5%. The payback time of 5 years is another major highlight of this system. In addition, the actual cost of the system is $18,844 while the projected cost modeled is $15,425. An addition of the battery resulted in insignificant improvements in power generation, higher projected cost of $20,466, lower ROI of 17.21% and a longer payback period of 5.8 years. The major losses in the system’s production are due to shading and soiling, which add up to 64,899 kWh in the lifetime of the system. Finally, GHG emissions of the current system total up to 38,000 kgCO₂e/kWh.