Now the solar hot water is installed and happy, I was pondering further solar installations. The question is: is it more effective to get my own solar panels, and get green power for whatever I can’t generate myself, or just switch entirely to green power?

First thing to do is reduce my consumption. My previous bills indicate it’s generally in the range of 8-10 kWh per day. And thanks to Josh giving me the Watt-O-Meter (or whatever it’s called), I know how many watts most of my appliances use. (Does anybody else want to have a go with this thing? I should pass it on.)

Almost all the bulbs have already been replaced with CFLs, need to get the last couple of tricky installations done.

I’ve isolated the computers so they are now switched off at the wall. From the Watt-O-Meter I know the computers and the XBox together use 45 W while doing nothing, so if they’re switched off two-thirds of the time (and it’s probably more than that), that’s 0.72 kWh saved. Most of the other appliances don’t draw that much power when not being used, but I’ll see what else can be done.

If I get panels, 1 kW solar installation is now about $4500 after rebates. Unlike people who are off in the wilderness, off the grid, this doesn’t use batteries, but works in conjunction with existing electricity supply: if you’re generating more than you’re using, the excess is pumped into the grid and you actually earn money for it. If you’re using more than you’re generating, the excess is pulled from the grid, and you pay for it.

Apparently typically a 1 kW solar system in Melbourne will produce 3.15 kWh per day, so effectively I’d be saving about a third of my electricity bill and associated emissions (though the amount saved depends whether that’s peak or off-peak).

A 1.5 kW system — costing about $8700 after rebates — would produce 4.7 kWh per day.

Given Victoria’s reliance on filthy brown coal for power generation, I really like this idea. It’s a bit pricey though, and I think it should be measured-up against investing in green power elsewhere which might be more efficient.

Switching to 100% green power is the other thing. (I’m on Origin’s Green for Footy plan, but that’s only 20% green power. It’s not that obvious when you join, which is why I chose it…) Tony pointed out this survey of suppliers.

For Victoria, Origin (who I’m already with) will provide 100% green power for an extra 5-6 cents (depending on whether it’s wind or solar) per kWh above the normal rates.

So which 100% green power works out cheapest?

Rough calculations based on my current usage…

100% green power for all my usage would cost about $197.10 extra per year.

Getting a 1 kW solar installation would cost me $4500 and an extra $128.11 per year to convert the rest of my power to Green.

Getting a 1.5 kW solar installation would cost me $8700 and an extra $94.17 per year.

While I’d like nothing better than to cover my roof in more solar panels, perhaps for now it’s easiest (and less capital outlay) to convert to 100% green power.