a quick and simple way of working out the viability of a solar system is through the following equation:
size (in kw) x 0.85 (consdervative "de-rate") x average Peak Sun Hours.
Average Peak Sun Hours is a published figure but the 3 i do have are Brisbane at 5.4psh, Sydney at 5.1psh and Melbourne at 4.6psh. This figure is the average hours of "Peak Sun" per day across the year so it factors in all seasons.
Peak Sun hours is where the sun generates 1kw/m2 per hour - there is a lot more in it, but that will do for simplicity.
using the example above a 5kw system in Brisbane would look like this:
5 x 0.85 x 5.4 = 22.95.
This is basically saying that a 5kw in Brisbane will on average produce conservatively 22.95kwh per day. Now if you look at your bill, it will tell you on average per day what your usage is. A good quality system will usually produce more and a cheap rubbish system may struggle to get there.
Another way to look at it is that ****very roughly**** each kw on your roof will produce ABOUT $100 worth of power per quarter. AGAIN - that is a VERY rough way of looking at it and does not take into account a myriad of factors.
as for equipment - the simple answer is always get the best you can afford. I am sick of seeing these el-cheapo companies selling $2 shop quality products that are several years old (they sell them here because the germans stopped importing them during the GFC - and we are suckers!!).
I agree with hiequity that SMA are a good inverter, though i will pick a fight (
)because there are a few other great ones as well - my personal favourite is Aurora/Powerone. SolarMax is also OK and even Samil are reasonable now (yes some say their history is a bit naff - but liken them to Hyundai, once ordinary now pretty good).
avoid the cheap advertised specials on the tele like the plague.
look at pricing and equipment comparisons very carefully - a lot of companies put hidden extras on top of their "specials".
Only ever use a tier one panel.
some good ones have been mentioned but Simax, Phono and Seraphim and CSun, Sungrid are also good to check out.
Don't use certegy to pay for it unless you have no other way to do it - even though it is "interest free" and you get a set payment, naturally the seller has factored that into the price and it costs a bucket.
is it worth it? in my humble opinion abso-flippin-lutely... but i am biased having been in the industry for a while.
If you do it right, you should generally be able to put a good high quality system on the roof with an ROI of around 3-3.5 yrs (quicker if you're careful with power and make a few simple changes around the home). As for changing bulbs and all that jazz - heck yes, but you might as well get the solar on and working for you now so you don't have a bill and work your way through the other stuff to maximise your returns and this way you can track your production and usage very well!
There are some very good battery banked systems out there that do allow you to grid feed and store power as well and the costs are coming down, still high at the moment, but is an option especially if you're not metro - we are due to see the next advance in this space in australia in about a month in terms of battery technology so keen to see where this goes.
My advice? always go 5-6kw (in queensland) and as large as you can elsewhere (sorry, dont know the rules o/s of QLD). You should have no bill at all and be in perpetual credit.
hope this helps some.
