We're working on the design of a solar powered cathodic protection system where the requirement is NiCad batteries. Since they operate on different voltages and have quite different deep-cycle characteristics, can HOMER actually handle them?
HOMER's battery module is flexible enough to model a fairly wide variety of energy storage technologies, not just lead-acid. I do not have much data on NiCd batteries, but I suspect that HOMER can model them fairly well.
My guess is that HOMER's assumption of a fixed lifetime throughput might not be as accurate for NiCd batteries as for lead-acid batteries. That assumption states that a certain number of kWh can cycle through the battery before it dies, and that "lifetime throughput" number does not depend of the depth of discharges or the charge-discharge pattern.
That assumption is acceptably accurate for lead-acid batteries, but it may be less so for NiCd batteries. Again, that is just my guess -- it may in fact be more accurate for NiCd batteries. The way to find out would be to enter a lifetime curve into HOMER's Create New Battery window, and see if the lifetime throughput tends to stay relatively constant versus depth of discharge.
Another assumption that may be less accurate for NiCd batteries is the assumption that the performance of the battery does not change with age.
HOMER assumes that the battery performs as new right up until the time that it needs to be replaced. Another of HOMER's assumption, that the battery's performance does not depend on the temperature, is probably more accurate for NiCd batteries than for lead-acid batteries.