This can range between 20 to 100 per cent. It depends on your roof or ground mount availability, which must be free of obstructions such as vent stacks, chimney, and roof contours. It also depends on how energy efficient your building is. The more efficient you make your building, the less energy you need to consume. We recommend having a certified Energy Advisor assess your house and provide tips to increase efficiency. We like Energy Advise in the East Kootenays and 3West in the West Kootenays.