Homes That Use Solar Power Without Being Fully Grid Tied: A Deep Dive
When it comes to solar energy systems, grid-tied systems with net metering are the most common and popular choice. However, there are scenarios where homes opt for setups that are not fully grid tied. These setups offer a mix of grid-tied and off-grid features, allowing for a certain level of energy independence while still benefiting from the grid for backup or when solar generation is insufficient.
Grid-Tied Systems and Net Metering
Grid-tied solar power systems, often referred to as "grid-tied systems with net metering," are the most widespread solar energy setups. In these systems, any excess energy generated by the solar panels is sent back to the grid through a process known as net metering. This allows homeowners to earn credits for the extra energy they generate, which can then be used during times when their panels do not produce enough energy to meet their needs.
At the heart of a typical grid-tied system is a PV array, which can range in size from a few kilowatts to several dozen kilowatts. For instance, our house has a PV array of 12 kW, making it capable of generating a substantial amount of energy. This energy can be used in real-time to power various household appliances, thus reducing our reliance on the grid during daylight hours. However, when the energy generated is insufficient, or during periods of low generation (such as at night, on cloudy days, or in the winter months), the grid serves as a backup to ensure that the home remains powered.
Why Not Be Fully Grid Tied?
While grid-tied systems with net metering are advantageous in terms of simplicity and cost, they come with limitations. A key drawback is that one is dependent on the grid for all energy needs. In situations where the sun is not shining, whether due to weather, time of day, or demand spikes, the grid becomes crucial for meeting energy consumption needs.
Furthermore, grid-tied systems require significant upfront costs to ensure that the system can meet the home’s peak demand without the grid. This means that the system must be robust enough to handle the highest energy consumption scenarios. However, adding extra capacity to a grid-tied system can be expensive, and it may not be feasible for every home to enhance its generation capabilities to the point where it is fully self-sufficient.
Examples of Non-Fully Grid Tied Systems
Many homeowners opt for setups that integrate both grid-tied and off-grid features. This hybrid approach allows for a more flexible and cost-effective energy solution. For example, a typical home might have a PV array connected to the grid via microinverters for net metering benefits. Additionally, it might also have a smaller battery bank to store excess energy or to power critical loads directly from the battery during outages. In my home, I have a system with 30 panels that are grid-tied via microinverters. These panels supply a significant portion of my energy needs and earn credits via net metering. However, I also have a separate setup of 12 panels connected to a battery bank, which powers the main circuits when the grid goes down.
This dual approach offers a unique balance between energy independence and cost-effectiveness. By leveraging the grid for surplus energy generation and storing excess energy in a battery bank, homes can achieve a level of energy security that traditional grid-tied systems alone cannot provide. This setup is particularly useful in regions with variable weather conditions and high energy demand variability.
Conclusion
While fully grid-tied systems with net metering are highly convenient and cost-effective, there are scenarios where integrating off-grid features into the setup can provide more flexibility and energy independence. Hybrid solar systems that combine grid-tied and off-grid capabilities offer a balanced approach, ensuring that homes can benefit from both the reliability of the grid and the self-sufficiency of on-site energy storage. This blend of technologies makes for a more resilient and efficient energy solution for modern homes.