s2s - I dips me lid to your superior knowledge....but I still think it's all Greek.
Can you use your little spreadsheet thingy and make like dollars and cents, so we have an answer to majiks problem?
majik
While I do see your point - and agree - that the FIT rate at the moment is quite low, especially when compared to what the previous "encouragement" FITs were offering, it is still better than a poke in the eye with a blunt stick.
Really it just means that the time factor of the return on capex is longer.
Now, to your household usage issues:
- the washer drier on daily: there are two issues here; firstly, you are probably washing too many clothes that don't necessarily need to be washed - especially things like towels - and secondly, you need to utilise a clothes line not a drier.
Towels used only once or twice are NOT "dirty" they are simply wet. You DO use soap when you bathe, right? And rinse off the soap before you get out of the shower, right? So all you are wiping off is plain, clean, water. Hang the towels out to dry on a clothesline and re-use them the next day.
Driers cost BIG time. Most are 2400W, or 2.4kW/h, or around 75c/hr. A single load of washing usually requires at least two hours of drying time, so call it $1.50 per load. So if you're doing two loads per day that's $3/day, or $270 per quarter.
Sunshine is FREE...!!!
If you are in an area which has minimal sunshine, rig a pull-out clothes line in the garage, under the eaves, under a verandah roof - anywhere out of the rain - and instruct SWMBO to use it. 
One of my clients said this was impossible because the car was in the garage. I pointed out that, unlike clothes, cars are designed to sit outside in the rain. And it costs you nothing to leave them there. She got the point.
As to the TV-sized screens - get a laptop. They use around 1/3rd of the power of a PC, if not less in your case. If that's impossible at least ensure the screen-off function is set for 15 seconds, so if you get up to check on the weather, the screen shuts off, at the very least.
If you are watching a computer screen or TV, you do NOT need a separate light fixture to be switched on. The screen light is enough to see what you're doing. If you need to read something on paper, have a desk lamp with an 11W fluro globe, and turn it off when you've finished reading.
And I'll equally bet that all of those appliances - PCs, TVs, VCRs, DVD players, have standby on 24/7/365...??? Standby can be as much as 5% of total consumption in larger households, as so many appliances are using small amounts constantly. Use remote-control piggy-back plugs to turn them off at night, at the very least.
As to the daylight vs electric light issue, why not install a couple of strategically placed light tubes, to let in the light from above the roof? One in the kitchen and one in the constant use office or TV area would mean you'd need no lights on at all.
Three TVs on 16 hrs a day...???? What are you watching, and why??? If by chance you have a bed-ridden invalid in the home, I could understand one TV being on constantly, but three...??
If it's only background noise that is on for comfort (ie: people are not happy with silence in the home) then could I suggest a small battery-operated radio would use a LOT less power, and still enable you to keep in touch with the world. And rechargeable batteries would be more eco-friendly.
As to the A/C units, you say you have two ducted systems and one split, right? The split will probably use less power than either of the other two, so use it for preference.
Secondly, most people put A/C on well before it is needed. Here's an exercise for you to convince the other household members of this: blow on the back of your hand. Your skin feels cooler as you do it, right? This is a well-known scientific principle called evaporation. Microscopic beads of sweat on the skin evaporate, taking the heat from inside your body out of the body (entropy principle...google it).
Sooooo, most of the time you only need a slight breeze to be "cooler". There is no *need* to mechanically (and expensively) remove the heat from the air around you.
So use fans in preference to the A/C units, until such time as the ambient temperature reaches around 30degC. Most people are quite comfortable up to this temperature with just fans.
Fans generally cost around 1c/hr to run, compared to the 75c/hr each of the A/C units is probably costing. And that's if they are all small units. If you have a large ducted unit, it might be a 10kW unit that could be costing you $3/hr to run. Five hours a day x 90 days = $1440/quarter. Probably won't be that bad, but you get the idea.
If you cannot avoid using one of the ducted systems, then check which rooms have ducts opening into them. Most A/C units are built down to a price, not up to an efficient standard, so you cannot avoid cooling/heating rooms and spaces that don't *really* need to be cooled. If the ducts can't be easily closed, buy duct covers that CAN be easily closed, say be reaching up with a broom handle and flicking a lever, and keep the ducts closed in rooms you're not using right now.
Are the actual ducts in the roof space properly insulated? Bet they're not. So wrapping the ducts with additional insulation can dramatically reduce the amount of heat absorbed from inside the ceiling space. Remember entropy? If the ceiling space is hotter than the air inside the ducts, heat passes into the duct, warming the air, thus requiring the motor to run for longer to keep the temp down and remove the additional heat.
Also, most A/C units are installed poorly, such that the return duct is not returning into the same space as the air is being drawn from. Split systems do this much better.
The outlet on the wall unit is also the inlet, so the machine is recycling the already cooler air from inside the room. Like the A/C on your car. Set it for "Recycle" and it keeps the inside of the car much cooler than if you set it for "Fresh". Why? Because you're re-cooling already cooler air, rather than trying to cool warm air from outside the car all the time. Much less efficient.
Hence most domestic A/C units are much less efficient that they *could* be, simply because of the cheapskate, down to a price way in which they are installed. It's called 'zoning' and needs to be physically separated as much as electrically.
This also why older houses are cheaper to cool and heat than the more modern "open plan" style of house. The spaces to be cooled/heated are smaller, and are *physically* capable of being separated. In a modern house, if you're working in the kitchen/diner, you are probably also cooling the rest of the ground floor, even though you aren't actually using that space at the time. Total waste of energy and dollars.
In most two-storey houses, the return duct is in the upstairs corridor - in summer, the hottest part of the house. So the poor overworked A/C unit has to constantly cool heated air, rather than the already cooler air discharged into the downstairs living space.
Also, cool air is heavier, so it sinks. If you are cooling the upstairs of a two-storey house, the cold air falls down the stairwell. If you are only cooling the bedroom/s, the return duct is usually in the corridor, so again you are contantly having to cool heated air. [Note: in winter this is reversed, as hot air rises, so if you are heating downstairs, the heated air rises up the stairwell, warming the upstairs space you are probably not actually using, most of the time.]
Hence why a split system installed inside the bedroom is more efficient. Close the door and you are only cooling/heating the small space inside the room. Doesn't take long and you can then usually turn the expensive A/C unit off and use a small fan to circulate the now-cooled air in the room.
And are they left on all night??? Shame on you! Once you're asleep you won't realise the A/C has turned off, so rig them with timers. Run the A/C for half an hour before you got to bed, then turn on a small oscillating fan. MUCH cheaper to run, and will still keep you cool (see entropy).
Buy one of those battery operated 'weather stations' that have a remote unit outside, so you can see the difference between indoors and outside temperature. Often our brains trick us into believing we are hotter or colder than in fact we are, and having empirical evidence of this can help your brain adjust.
For example, in winter, 20degC is cold enough we require a jumper or jacket to keep warm. So why is it considered necessary to cool the house to this level in summer...???
For every degree higher you can comfortably leave the A/C temp you will save around 10% of the usage over time. So setting the temp on the A/C unit for 25degC, rather than 20degC should save you a significant amount. Again, watch the 'weather station' and when the temp reaches 25degC, turn the A/C off and use a small oscillating fan to circualte the cooled air. Eventually the temp will rise to 30degC at which point turn the A/C back on.
If you leave the whole house on 'autopilot' it is costing you money. *Drive* the household's consumption manually and you can't avoid driving it DOWN. Using less energy saves you money.
Reward your family members with a nice dinner or a holiday with the money saved. Give them an incentive to join the party!
Do I dare ask if the house is properly insulated? Do you have R3 batts in the ceiling at least..?? If not, every time you turn on the ducted A/C you might as well take the money out of your wallet and set fire to it. You'll achieve the same effect.
And finally, have you not heard the expression "he who pays the piper calls the tune"??
It's time to toughen up and put your foot down. If people want to live the "lifestyles" of the rich and infamous, then tell them to get out there and earn the millions necessary to support that sort of environmentally destructive 'lifestyle'.
Even on your 7% returns, you are clearly not enjoying shelling out all *your* hard-earned..... Else why are you here, asking questions.... :)
Hope the above is helpful, or at least prompts you to further thoughts on the subject of energy efficiency.
As most of my clients have learned, it doesn't take much actual expenditure to dramatically improve your own efficiency, and the savings from doing so can then offset the capital expense of taking the next, capital intensive steps to further reduce your overheads - and your energy footprint.
Good luck!!
