Battery-backed or grid-independent systems use on-site energy storage to store excess energy produced during the day for use at night or when the sun is not producing enough power. Choosing this option will add significant cost and maintenance to your system. Most people opt for grid-connected systems for reduced cost, maintenance, and high reliability. With this type of system, your cooperative continues to provide energy to you when you need it 24-7. Your PV system will produce energy, and even excess energy, on sunny days. Your system will not collect sunlight at night and on cloudy days. That means you will continue to draw electricity from your cooperative during these times.