"Adequate years of service performance and lifespan is the ultimate BS detector"
Too bad this cannot be "adequately" translated universally. Perceptions vary.
$ invested per kWh transacted is the ultimate formula but how many folks would understand how to audit such as this - never mind do it.
On a giant system it costs X total gross $ to extract "X" kWh of energy from a battery bank. It includes costs of first generation purchase of storage batteries, cost of recharging mode, cost of installation, subjective "cost" of maintenance, and ambiguous determination of end-of-service life capacity.
Complicated by adjustments of amortization for subsequent replacement of batteries, repair of charging and electrical transmission circuits. AKA cables, terminals, all maintenance. Includes $ distilled water for flooded batteries.
A full system audit demands meticulous record keeping, including maintenance man hours, cost of procuring fuel, man hours to clean solar panels, cost projection for warranty claims, etc.
To say this exercises the keypad of a calculator may be an understatement.
It can only be rationalized on an extremely large system.
