The Solar Converters unit is preferred for most applications that require 24 volts or less, and .40 to 15 amps. The AERL units are capable of going up to 180 volts on the standard units. Many still use the old resistor taps for current adjustment. These controller losses translate directly into money. Solar power is expensive, but in many designs it is much more expensive than it has to be.
Many older systems have some pretty primitive controls.
From what we have seen, the majority of them are not working - some have not worked for years. Using our control systems for a retrofit, using your existing panels, can restore operation to normal. In almost all cases, it will improve system capacity and reliability. If your system has been down for more than a few weeks, it is almost certain that you will need new batteries. This translates not just into fewer panels, but a smaller battery system, less wiring, and a smaller mounting system.