Smashed Crab wrote:dedja wrote:To be honest it’s a can of worms.
There are so many variables to consider.
Do you currently receive any State Govt FIT? If so, you’ll lose it if you change anything.
What size is your current system? What’s your usage pattern wrt import/export?
If you’re currently on a single rate plan you’ll have to go on TOU with a smart meter.
What is the reason for considering batteries? What outcome are you aiming to achieve?
From my research, the payback period would be at last 10 years, but when you take into account their service life, there’s not much opportunity for there to be a payback on the investment.
YMMV though.
When we built our house in 21/22 we only put panels up, I am spewing I didn't put the extra $10-12k into a battery at the time. Instead of paying 50-55c/kwh once the sun sets we now use battery over the night so we rarely need to pay for power. Sure the feed in tariff is crap, but paying stupid amounts for using power is also crap. We put a battery in in lat April and in just this 8 months our calculations have shown we've saved $2300 (if no battery or solar panels). Our pay back is anticipated to be 5 years. Price of electricity is only going up. The only saving grace will be if Liberal gets in next and starts the Nuclear revolution.
SET <verbose mode> = ONSaving sound good, but best to evaluate after a full year’s usage.
The SA State Govt FIT schemes are as follows:
Install date 01/07/2008-30/09/2011: 44c FIT until 30/06/2028
Install date 01/10/2011-30/09/2013: 16c FIT until 30/09/2016
Install date after 01/10/2013: no FIT
You can receive a Retailer FIT on top of the State Govt FIT.
Your equation is completely opposite to mine. I receive a huge FIT as I’m on the State Govt 44c scheme (panels installed in 2011) so the most profitable scenario for me is to push my high demand usage to night and minimise daytime usage to maximise export. I’m also on a singe rate plan (not TOU) which means I pay much less for import. This scheme runs out on 30/06/2028, so I’m aiming to keep off TOU until then if I can.
In your case (and anyone else who installed panels after Sept 2013), your aim is to maximise power usage during the day to minimise import and don’t care about export. The obvious benefit of the battery is that if you have excess power generation, your can store and use that power when there is low or no generation (ie. at night). In order to maximise the benefit of batteries, you need to ensure that you have enough excess generation to be able to store in the battery to get you through the rest of the day, and a battery big enough to store all that excess power. You also need to be able to tweak your settings to store that excess generation in the battery in preference to exporting to the grid.
The kicker is TOU. In SA, we have the most punitive TOU in the country due to our high renewable generation in the state. ie. peak times are longer here than anywhere else.
Off Peak: 1am-6am
Solar Sponge (Shoulder): 10am-3pm
Peak: 6am-10am, 3pm-1am
So with TOU, you obviously want to minimise your import during Peak times. Then it’s a matter of working out your usage pattern and working out a panel and corresponding battery size to minimise cost, plus at the same time ensuring that there actually is a long term cost benefit (no point saving on operating power costs if you have a very large capital outlay to achieve that and never actually recoup your investment).
Another consideration is solar panel and battery expected lifespan. You should get 20-25 years for solar panels, and anywhere between 5-15 years for the battery, so a rough rule of thumb is for the lifecycle of the entire system, you need 1 x solar panel array + 2 x battery.
The final consideration is estimating future power pricing … we can only assume it will continue to increase for the foreseeable future.
If you take all of that into consideration, and the numbers are in your favour, then get the champagne out and celebrate. If the numbers don’t add up, then you have to decide whether you should sink a large cost today to reduce your ongoing costs into the future.
I need re-evaluate in mid 2028 and stay off TOU until then. For what it’s worth, if I were to build again, I would sink the cost of panels and battery during the build.
I did a lot of research before I installed my panels in 2011 … reviewed power usage, replaced power hungry lighting (eg. halogen down lights with LED), and had a detailed analysis of expected power generation. After 13 years, the actual power generation is bang on the estimates, and I have kept records of usage (import) during that time, so have a lot of good data for future scenarios when I need it. This also allows me to find the most appropriate retail plan for my situation.
In my case, my initial capital cost was $13.5K for a 4kW system (yes, much more expensive back then), and the actual payback was 7 years. My average yearly saving since the system paid for itself is approx $2.7K per year
It’s as complicated as faaark, so just go in with your eyes open.
Dunno if this helps anyone, but hopefully it does.
SET <verbose mode> = OFFDunno, I’m just an idiot.
