!!

Two 10-minute showers per day (one for me, one for SWMBO) would nearly double my electric bill, from $183 per year to $319 per year. And yes, we have discovered through pleasant experience that sharing a shower does NOT save any hot water, since the time spent uhhh... showering increases dramatically.

If I hadn't already taken steps to minimize my electrical billing, that heater could easily end up more than tripling my annual electricity cost because of the punitive rates applied to high usage here.

BTW, I consider those punitive rates to be a Good Thing (tm) in the interests of conservation. My across-the-street neighbors have a large swimming pool, heated with passive solar (black pipes collecting sun on their roof) but with all the pumps and filters, etc, plus being a large house where they are careless with lighting, their electric bills run more than 15x mine. They are perpetually on the DAC (Domestic Alta Consuma) rate so in addition to their using a great many more kWh than I do, their rate per kWh is nearly four times mine (2.52 pesos per kWh vs. my rate of .71).

There may well be more economical methods of heating shower water, depending on where you live and what your various utility rates are.

tanstaafl.