I don't have gas either so cooking and hot water heater is electricity too.
Heating water is a massive arse when you read the science of it - comes down to the
specific heat capacity (that's a link). Water has a higher specific heat than nearly all metals, and it basically refers to the amount of energy required to raise the temperature of something by one degree celcius.
Gas rocks - requires the same amount of energy in cosmic terms to boil water, but setting things on fire seems to work better than asking metal to heat them up.
Which season is the one for you to use most power, summer or winter.
Sadly, mine would be winter which is not good from a solar perspective.
Looking at my last round of bills, purely on usage rather than pricing:
16 Sep - 16 Dec 2015: 1917kWh = 20.83 per diem on 92 days
28 Jun - 15 Sep 2015: 1806kWh = 22.575 per diem on 80 days
21 Mar - 27 Jun 2015: 1777kWh = 17.949 per diem on 99 days
19 Dec 2014 - 20 mar 2015: 2517kWh = 27.35 per diem on 92 days
For the 363 day year of billing, that averages 22 per day. Slight underestimation on my part, but insignificant to the big spreadsheet I put together before making this decision.
Therefore, peak summer is my weak point due to a wife who can't tolerate anything above 21C (except in winter when she can't tolerate anything below 23C
) and a pool pump that was highly inefficient.
In a way, that is good news, because the solar will take the load, the habits will be adjusted, and the pool pump has been replaced with something more efficient. So it can run 8 hours per day for free. When swimming season is over, I'll turn that down to 1-2 hours a day to keep the equipment turning over, and I don't give a shit what the pool store says
In terms of rebates: the current round of rebates for installing the solar are built into that price, so without that I'd have paid closer to $20K. I'm happy to take the subsidy, despite what all the twats on The Australian said about my privileged ability to pay for a system up front would do to the poor people, by forcing providers to up prices. I look at it this way: I pay my taxes, and I'm not a tax-neutral proposition like "the poor people", and help take the heat out of the market that seeks to rip
everyone off through poorly-thought-out projects like $45B in poles and wires.
You can sell back excess power to your energy provider for "x" cents per kWh (kilowatt hour), known as the "feed-in tariff". You can do this even without the battery (but I'm pursuing the Reposit model of market sale).
Energy Australia (my current lot) are paying 10 cents per kWh from memory, but selling it to people for 23.5c! I know guys at work who were on the old scheme, getting paid 40c or even 60c per kWh when the government had a boner for solar subsidies. That ends next year, and at the time their 1.5-2.1kW panels cost them close to $10K. They look at what I've got and agree its a bargain, given the amount of power I can generate, particularly as I can use it even after the sun pisses off.
Yesterday, despite an mildly overcast Sydney day, I generated 22kWh. Today, despite that fucking huge storm that rolled through, I generated 21kWh. A bloke who lives up at Wisemans Ferry behind a ruddy great hill said his 4kW system (so 80% capacity of mine) generated 30kWh one day!
So for me, its all gravy. The wife is getting on board with this, looking to maximise our battery recharge, minimise the spend, and shorten the ROI.
Primarily, the bulk of the dynamic running cost of our household is electricity on a quarterly basis. The mortgage is bigger, sure, but I get unlimited use of the house. Our gas bill is only about $150 per quarter, and I'm looking for a better price there, too. Water isn't much more. Rates are set and inescapable.
Cheers. That price isn't too deterring. Considering what it costs to run my house I would make that back fairly comfortably.
Yeah its kind of an easy decision. I guess the up-front cost scares people off, and the thought of investing in something for 8-10 years. The irony is that some people who shy away from this might spend the cost of my system in three years on booze, cigarettes, poker machines, or holidays.
I don't have ANY other investments. No property, no shares. That might come later, but for right now I've got to future-proof my running costs.
The variable I keep in mind for all my calculations is not yet understanding
when we use most of our power, and this is important for the battery setup: I can extend my solar power into darkness, and know that if I can get the solar panels to generate 16-25kW per day depending on the season, I'll cover the vast majority of my known usage given the patterns I've identified in this house (2 years last December) to date.
Its the last maybe 15% I need to get a feel for.
What is going to burn the most, and what
time of day will it happen?
Should I run the heat/air con on low for most of the day off the panels, or let the power sell out during the day, and burst the air con at night to let the battery take the strain?
Can the battery get us through until the morning in most circumstances, or will I be pulling grid for breakfast?
Should I forgo using the ducted for heating, and invest in a gas heater to cut electricity costs? Will the wife be able to handle that?
What is the ROI on the gas heater, relative to electricity?
These questions are all to be answered. I have a measure of confidence that the ability to resell power out of the battery in high generation times (Reposit) will offset any grid power I have to buy back (including connection fees).
But its not a simple analysis unless you've already got a smart-meter that can track back your usage to time-of-day (I don't).
Time will tell.
