I attended a funeral last night and happened to be sitting directly behind the widow of the deceased. She was talking to a friend about the last few months before her husband died. Because her husband needed an oxygen-producing device of some sort, she described her panic when an ice storm knocked out power at her home. She couldn’t understand why the device didn’t include a battery backup. At that moment my wife and I looked at each other, knowing that we could have provided a solution to her problem.
When an electrically powered device is necessary to sustain life, a backup source of power is an important consideration. While a generator might be the best backup strategy for a hospital or institution, it may not be the best solution for an individual with special needs who’s living at home. For a variety of reasons, it could fail when it’s needed most.
The most reliable system is the one with the fewest moving parts, and one that doesn’t depend upon the delivery, storage, and periodic replacement of fuel. A properly designed and installed solar photovoltaic (PV) system is the ideal system in this scenario.
A well designed PV system will have enough panels and a large enough battery bank to provide the needed power even during short winter days, and when the sun doesn’t shine for a few consecutive days. This is a departure from the typical off-grid PV system. Typically, off-grid PV systems are undersized for economic reasons, and a backup generator is used as needed.
To enhance its reliability, the PV system used as a power source for a life-sustaining device should not be used to provide power to anything other than the life-sustaining device itself. Furthermore, the PV system should be protected by proper grounding, and through the use lightning-protection devices. Over-sizing the inverter is another way to improve system reliability. Regular system tests or continuous monitoring equipment are important as well.
If my life depended upon an electrically-powered device I’d want that device to be powered by my own photovoltaic system. I would test the system periodically and inspect batteries and wiring. In addition, I would maintain an inventory of spare parts for the system. In other words, I’d attend to the system as if my life depended upon it.