Frequently Asked Questions
In Southwest Florida we are prone to hurricanes and storms that result in power outages. It is natural to want a backup to utility electric power, and common for people to assume that a solar electric system will provide backup during outages. There are generally two types of solar electric systems: grid-tied and off-grid. There are also hybrid systems. Hybrid systems allow you to have backup power during outages by using specialized inverter/chargers and a battery bank.
Grid-tied or grid-interactive systems connect to the utility power grid and do not provide backup during power outages. Your solar panels provide electricity to your home during the day with excess energy sold back to the utility company. Conversely, excess usage is purchased from the utility company. The benefit of a grid-tie system is that it uses a relatively low cost inverter, there is no costly battery bank required, and there is virtually no maintenance. A grid-tie system is also the most efficient use of the energy from your solar panels. The vast majority of solar energy systems sold today are grid-tied systems, which provide the best "bang for your buck."
Off-grid systems use a battery bank charged with solar power and an inverter to produce A/C power. There is no connection to the utility company. In this type of system, you are limited to the amount of solar energy your solar panels produce and how much storage capacity exists in your battery bank. These systems require a costly battery bank and limit you significantly to the amount of energy you can consume. The battery bank requires periodic maintenance and replacement.
A hybrid system uses a combination inverter/charger that can both charge batteries using your solar panels and sell excess electricity back to the utility company. This type of system provides maximum flexibility, and can even include a generator for even more reliability/redundancy (however, we do not promote fossil fuel burning generators). The greatest disadvantage is cost. The system components are significantly more expensive and complex. The battery bank requires periodic maintenance and replacement.
In conclusion, we often tell our customers to ask themselves how often they are really without utility power. A grid-tied solar electric system is what most people ultimately decide upon after weighing the alternatives.