In the UK power cuts are very rare in most places (and generators are cheap), so it's not a huge advantage. The enviroment factor is at best tenuous due to 20%

In the UK power cuts are very rare in most places (and generators are cheap), so it's not a huge advantage. The enviroment factor is at best tenuous due to 20% of energy stored lost as heat and high energy requirements for producing the batteries; and in any case unilateral green action makes no difference. The solar tie in is quite nice, but current feed-in tariffs are huge in the UK (30p per kWh perhaps), so you're getting more out of paying it back than you would for storing. Government incentives obviously change the calculations, but there aren't any at the moment.