Off Grid and Battery Backup Systems
Battery-based grid tie and stand alone systems include a battery bank for storage, either for backup use during an outage, or for daily cycling in an off grid or net zero application.
There are many types of battery technologies and chemistries available, and choosing the right battery from the start will save time and money.
Flooded lead acid batteries are one of the most common batteries for backup an off grid systems. FLA's are a good choice if low initial costs are the goal, but require maintenance, monitoring, and generators to obtain their full life expectancy. Lead acid batteries like to be in a float charge stage 24 hrs, were they are seldom used. Increasing the size of the array by at least 30% will help in preventing sulfating of the battery plates.
Sodium-ion battery eliminate the need for an oversized solar array because of they tolerate long periods of discharge without damage to the battery. The initial investment of this battery type is much higher, but they have many more cycles (6,000 at 50% DOD) than a lead acid battery (800-2100 at 50% DOD), and are sealed and require no maintenance.
Lithium Ion batteries, like the LG Chem, come in a variety of sizes, have a long life. They are a great choice for net zero systems, when net metering is not available. Lithium Ion Phosphate batteries are best used for larger off grid systems.
Edison Iron batteries have the longest life, up to 75 years. They require watering and have a high initial costs, but will probably be the last battery you will buy.
Especially when considering lead acid batteries, special mounting methods are sometimes incorporated into the system design to decrease daily cycling. For example, using a single axis tracker sized for an air conditioner load in the summer months will dramatically reduce the dependence of energy storage. On demand propane generators can also be a good choice for protecting batteries during long periods of low light conditions.
Designing a stand alone system requires a careful analysis of your homes loads and time of use. Sometimes small lifestyle adjustments make a big difference in the size and cost of a stand alone system. Please feel free to reach out to us for a free consultation. Visit our Contact Us.