Tesla's battery put in the shade by current and cheaper kit

Reality pays the pretty Powerwall a visit

A couple more interesting details have emerged about Tesla's “game-changing” home battery, and it remains a moderately limp competitor that's done wonders for market awareness.

Courtesy of Bloomberg, the world gets an idea of what the retail from-the-installer price of the battery might look like (rather than the wholesale price the 'leccy car maker announced last week).

The Elon Musk-led system seller SolarCity, Bloomberg reports, will ship an installed 10 kWh Powerwall for US$7,140 (ouch outright purchase) or $US5,000 plus a nine-year lease.

To match a 16 kW generator that sells in the US for just US$3,699, the reporter works out, would require around US$45,000 worth of Powerwalls on the lease deal.

Bloomberg New Energy Finance doesn't imagine the Powerwall making a dent in European markets like Germany, where the economics of solar power are well-understood. Its take is that “the economics of an average home with rooftop solar are not significantly enhanced by including the Tesla battery”.

The problem with the larger battery gets worse, with SolarCity's Jonathan Bass telling Bloomberg the 10 kWh unit is limited to around 50 charging cycles per year (500 over its lifetime).

That makes the 10 kWh version entirely unsuitable for off-grid applications, leaving the 7.5 kWh Powerwall as the only contender in that market.

Bloomberg also provides nice validation for The Register's assessment of the 2 kW output limit for the Powerwall batteries: “The model puts out just 2 kilowatts of continuous power, which could be pretty much maxed out by a single vacuum cleaner, hair drier, microwave oven or a clothes iron.”

That hasn't stopped Musk saying, in Tesla's earnings call, that 38,000 people have reserved batteries. Let's just hope that they don't all drown in the trough of disappointment. ®