Off-Grid Solar Battery Systems
March, 2014
Off-grid solar systems were the starting point for much of the solar industry years ago. Now, the majority of solar arrays are connected to the grid with a relatively small percentage of those providing battery backup. However, for certain, select customers, an off-grid system may be the right choice. The first, and most important step when considering an off-grid system is minimizing your power usage needs. This will decrease the system complexity and the system design.
When Sizing an Off-Grid System Consider Five Factors:
- Estimated daily usage and expected maximum power draw (Load/Consumption Analysis)
- Solar resource (Amount of Available Sunlight)
- Number of days of autonomy (Days of Battery Storage When There is Minimal Sunlight)
- Additional back-up power sources (Generators for Example)
- Budget
The load analysis is extremely important as you’ll likely consider further decreasing your energy requirements once you fully evaluate your costs. When choosing appliances, energy efficient DC-powered appliances will maximize your investment and the success of the project.
Off-grid systems are somewhat similar to DC Coupled systems. However, the inverter will not connect to the grid and the battery-bank is larger due to the need to provide power for extended time periods (a typical design is 2 – 3 days of autonomy). It’s also important to recognize that off-grid systems will require more monitoring and maintenance than a simple grid-tied system. Specifically, the battery systems are typically lead-acid batteries that require maintenance to maximize the system’s safety and long-term viability. Because the batteries are used frequently, they will need to be replaced sooner than those in a grid-tied battery backup system.
An Off-Grid System is Perfect for Someone Who:
- Would have a large cost to connect to the grid or experiences frequent power outages
- Will limit their energy usage and modify their lifestyle to live within the capabilities of the system
- Is willing to evaluate and maintain the system
Combining a generator with your solar array will provide additional capacity to the system and potentially allow you to consider a smaller battery bank since the generator can offset the shortfall when there is limited sun.
