Canandaigua, NY 7.2 kw solar electric system
Challenge
This 7,200 W (7.2 kW) grid-connected solar electric (PV, photovoltaic) system was installed as a roof-mounted array of thirty-two (32) SunPower 225W solar modules oriented South on the house roof.
Solution
This 7,200 W (7.2 kW) grid-connected solar electric (PV, photovoltaic) system was installed as a roof-mounted array of thirty-two (32) SunPower 225W solar modules oriented South on the house roof. The array is arranged as five (5) rows of modules in landscape at a tilt of 10°. The modules will be mounted to the roof surface using a ballasted UniRac RapidRac mounting system that will ensure a structurally sound connection to the roof without penetrating the membrane material. Additional precautions - such as additional membrane roofing at the places of racking and roof interface - was taken with manufacturer and engineer consultation to protect the flat
roof from any wear over the long term. The system is configured electrically as four (4) DC circuits (strings) of eight (8) series connected modules providing input to one (1) SMA 7000m, 7.0kW inverter. This inverter communicates with one (1) SMA Sunny Island 5048-U, 5.0 kW battery-charging inverter, which provides charge control for the battery bank, and produces high-quality AC
power for the house loads. Specifically, during normal grid operation, the SMA Sunny Island 5048-U, 5.0 kW inverter provides AC power to all loads, maintains the battery bank at full charge, and sends any extra electricity back into the grid. When the grid is down, this inverter provides AC power to the house loads in the critical load panel, and continually charges the battery bank using the solar electric system. The SMA Sunny Island 5048-U can also operate an AC generator if needed or desired in the future. This residential battery storage
system is designed to integrate with the solar electric system to provide stable, quiet, and low maintenance backup power to the critical house loads. The system is comprised of eight (8) Concorde PVX-4050HT deep-cycle AGM/valve-regulated lead acid (VRLA) maintenance-free batteries to provide 8 x 6V x 405Ah = 19.4 kWh of energy storage (11.7 kWH effective capacity). This battery bank
should provide at least two (2) days of critical load backup (a minimum of around 6.0 kWh/day) before recharge is required (for reference, the Customer's current normal daily usage is around 25 kWh/day). System power production (kW) and cumulative energy (kWh) monitoring will be provided by a SunPower Monitoring System, as well as by a digital display on the inverters and an electromechanical meter. As designed, this system should generate an average of 20.3 kWh/day = 7,409 kWh/year, where daily energy production is both weather and seasonally dependent. This energy production is equivalent to 82% of the customer's present home electrical usage, and corresponds to a CO2 (greenhouse gas) emissions savings of 3,334 kg per year.
