Some homeowners choose to go off the power grid because they want an energy system that is completely autonomous, others because they want a system they know uses entirely green energy. The owners of one residence in La Honda, California, wanted both when they built their new home outside of the utility’s service territory.
Originally, the home ran two diesel generators for power. In the early 2000s, the homeowners switched to a solar + battery system to meet the majority of their needs.
This off-grid La Honda, California residence went from diesel generator to solar + storage
To support the nighttime loads and provide emergency backup, the homeowners and their installer put in a very large system of sealed lead acid batteries. At the time, these were the only types of batteries feasible for residential applications.
The batteries were operating under very simple system control, whose blunt charge/discharge profiles would have worked a normally sized battery system fairly hard, limiting the batteries' expected lifetime. To guarantee longer system life, the batteries were significantly oversized, to the point that they only discharged around 10% on a typical day.
Finding A Better Solution
As the battery system began to reach end of life, it became obvious that the home needed a new storage solution, a drop-in lead acid battery replacement. The system needed to be completely maintenance free and, ideally, would also cost less than the oversized lead acid system. Most importantly, the new system needed to perform as well as the lead acid system and last just as long.
Aquion Energy batteries would provide all these benefits, and more.
Replacing a Lead Acid Battery System
In progress: This photo shows Aquion batteries on the left, and the remaining lead acid batteries that were being replaced on the right.
The new system, featuring Aquion batteries, was not only much smaller, but less expensive than the original lead acid installation. Since the can be discharged 100% without degradation, the Aquion batteries did not need to be oversized to meet the customer’s lifetime requirements, which meant the nominal kWh of the Aquion batteries could be much lower. Compared to the 500 kWh lead acid installation, the installed Aquion batteries amounted to only 90 kWh. As seen in the photo above, the Aquion batteries fit into the footprint of the lead acid system but stood only a third as tall.
This also meant that the system with Aquion batteries was much easier to install. Aquion's S10 stacks could be lifted and moved with a simple crane, and wired together using solar combiner boxes, a much safer and simpler solution than the large, heavy lead acid bank. Even removing the lead acid system was a challenge, as many of the 100+ pound batteries had swelled in their casing and had to be removed from shelves eight feet off the ground.
In order to install an Aquion battery system that was much smaller than the original lead acid system, it was critical to take into consideration the power demands. Though in most applications, energy requirements determine the size of the system, in some cases the power may be the determining factor. Lead acid is more power-capable than AHI batteries, and an oversized system is that much more so. This meant it was important to take into consideration the power use of the home when determining the minimum size of the new Aquion battery system.
A Seamless Transition
For this residence, Aquion batteries provided a near-perfect solution. The Aquion-powered solution was lower cost, smaller, and more environmentally-friendly than the previous, lead acid system. It also requires no maintenance and meets the power demands of the user. For these reasons, Aquion batteries are a great solution to replace lead acid.
The final installation.