A friend of mine told me he's keen to get solar power for his house, I thought I'd run it past people here to see if they had any thoughts or useful advice. I can get proper details if anyone's interested.

The house is in a Wellington suburb, on a peak, with a perfect north facing roof. The house has four adults and two kids, including two hot water cylinders and a spa pool, with people occasionally home during the weekdays and home most weekends. An electric car is a possibility in the future, the idea being to charge it on the weekends for a weeks commuting. They're not thinking about storage batteries right now, but might think about that in a few years, so they system will be designed to accept them later. Their power bill is fairly high, from memory they said around $300 - $400 in summer and $600 in winter - TBC. It's an older house, relined, double glazed downstairs where it's a self contained living area, but single glazed upstairs where the main living / sleeping area is.

The system will has some kind of a gizmo (I forgot what he called it) which channels the power into heating the hot water during the day, preventing them heating in the evening - though I guess there could be an override button somewhere. So while there's no power storage the water heating is storage of a sort.

The panels and install are costing around $12K for 20 panels (no idea of brand/spec) and $1500 for the power router thingy.

Does solar sound like a good option/solution to reduce their power bills?

Edit - it's a 4kw system from Harrisons and the device thingy is an "immersion hot water device" that sends power where you want it to go.