Storage from Off Peak Usage in Peak

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Re: Storage from Off Peak Usage in Peak

Postby barry_mcki » Thu Jun 20, 2013 12:45 am

ATA posted an article in their Apr-Jun 2013 (#123) ReNew magazine on this subject. They used NSW ToU as the model. The article was mainly foucused on the financial side of things, however looking at one of the tables it appears they used 70% efficiency on the battery discharge.

The overall analysis was that over a 10 year payback period (the system was costed at almost $20k for a 12kWh per day), the Peak Tariff would need to be 72c/kWh higher than off-peak, i.e. no, it's not worth it yet.

ATA promise to do another analysis adding solar to the equation. There is a fair bit of info in the two pages given to the article, I've only just glanced over it. You should be able to pickup ReNew from most news agents, there should be a back issue section in the mag somewhere if you want to order it.

PS I'm not affiliated with Renew - I just think it's a great mag.
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Re: Storage from Off Peak Usage in Peak

Postby Tracker » Thu Jun 20, 2013 9:05 am

barry_mcki wrote:The overall analysis was that over a 10 year payback period (the system was costed at almost $20k for a 12kWh per day), the Peak Tariff would need to be 72c/kWh higher than off-peak, i.e. no, it's not worth it yet.

So, 72 plus say 15 for off peak , means the cost would be about double the peak rate..

Add to this, the calculations of those who have lived with Island Power from necessity and the figure is likely pretty close to reality.. ie. You won't install a battery system and save money as well. It has to be a case of compromise...
The only way that I can see it really working is to have sufficient PV potential to power ALL your major living needs during the day, and then simply power low power stuff at night from a minimal battery setup..
This means washing , cooking etc.. possible if you like salads and casseroles ..

I am fairly convinced that the cheapest solution is to construct a a standard grid feed setup, and reduce your power bill.
After that, an augmentation system, where you have a PV system, powering a dedicated power circuit within the home, and utilising a minimum sized battery.
This gives a reduced overall household consumption, and a small amount of Black-Out cover, for those odd occurrence when you need island power..
This is what I am now doing.. using a small system that is hopefully, balanced for the appliances it runs.
It powers them during the Peak Power period, and then, whenever the battery is fully charged.. on a typical day it thus powers them (5 fridges) from about 10am to 8pm and still allows capacity for blackout cover..

I must say that I don't quite get the web site if it is only purchased content, and I will be frank and suggest that I thought it was written by a schoolie...
..
.
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Re: Storage from Off Peak Usage in Peak

Postby Tracker » Thu Jun 20, 2013 9:29 am

Majik wrote:..... The key question relates to the efficiency, hence economics, of (electrical) charge now at cheaper rate, then use later when high rate. Tracker confirmed my concern about the efficiency....

Again, I stress that this was with an inefficient inverter and charger.
Yes 2:1 ..... but even at that, this is a halving of the actual cost of Peak Power cost.
I had planned to repeat the same process with an efficient inverter and charger, but I have not done it, and as per previous comments.. gone down the Solar Offset track..
I do view it all as a progression to replacement of all consumption by solar.

I would guess that the cost of the basic "cost transfer " setup would have been about $8000.. massive.. :idea:
The battery cost is again... the killer..!

I stress that it is really not all that practical, financially .. the conservative new cost of what I now have is about $10000, and thus saving about 3 to 5 power units a day, it would take a very long time (if ever ) to pay off the system.. ie the batteries will likely need replacement b4 the first investment is paid off..

As for getting bits to experiment and learn, there is no end of options.. eg. You could buy a solar-skylight from Oatley Electronics to light up an internal hallway.
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
2 x CMS2000 (fan cooled) GCI and SE 170W panels
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Governments won't save the world :-) They will just TAX it :-(
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Re: Storage from Off Peak Usage in Peak

Postby FarmerJohn » Thu Jun 20, 2013 10:11 am

barry_mcki wrote:ATA posted an article in their Apr-Jun 2013 (#123) ReNew magazine on this subject. They used NSW ToU as the model. The article was mainly foucused on the financial side of things, however looking at one of the tables it appears they used 70% efficiency on the battery discharge.


It would be interesting to see those numbers for LiFePO4 with their 90% efficiency and longer cycle life.
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Re: Storage from Off Peak Usage in Peak

Postby FarmerJohn » Thu Jun 20, 2013 10:21 am

Majik wrote:davidg/Farmer John, as Tracker suggested, who knows if I am charging batteries?


Licensed electricians know the tariff rules and are not allowed to connect loads that are not allowed on certain tariffs - they just wont do it. I dont think you can have a GPO (Socket) connected to the off-peak circuits, but if I am wrong, then you are good to go.

If not, and you did do it illegally, and then got found out later somehow, I think you would be in quite a lot of trouble with a low chance of it ending well for your bank balance.

There are other problems too. Doing illegal electrical work on your house invalidates your insurance policy - because most of them insist on you following building codes, and one of those is that electrical work has to be done by a licensed electrician.

If you look at your agreement with your electricity company, you most likely agreed to follow those rules too - something you signed, so it is also a matter of honoring agreements you made explicitly and not just implicitly - it becomes a matter of honoring your word.

They have this pretty well wrapped up. I looked for every way out of that.

Off grid, and self insurance, is the only way out the trap.
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Re: Storage from Off Peak Usage in Peak

Postby bpratt » Thu Jun 20, 2013 11:03 am

FarmerJohn wrote:Licensed electricians know the tariff rules and are not allowed to connect loads that are not allowed on certain tariffs - they just wont do it. I dont think you can have a GPO (Socket) connected to the off-peak circuits, but if I am wrong, then you are good to go.


Up here in Queensland I did a little research on this topic, and as long as it is hardwired in, you can put it on to a off-peak circuit. The one exception is that you are allowed to have your pool pump to remain as a plug in item on an offpeak circuit.

Very handy as we have some of our A/C's hardwired in to offpeak circuits, and whilst you lose them for around 3 hours an evening, it's saving money for us.
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Re: Storage from Off Peak Usage in Peak

Postby Tracker » Thu Jun 20, 2013 11:58 am

FarmerJohn wrote:.....If not, and you did do it illegally, and then got found out later somehow, I think you would be in quite a lot of trouble.....

There are just SOOooo many variants of electricity tariffs around the States.. It is hard to generalise.
but, it's a given that "Generally" a true Off-Peak plan has limitations.
A general TOU plan with Off Peak, has no limitations.. ALL power at those times is costed at Off-Peak..
So - THEY have no idea what you use the power for..

As a very large generalisation, I would suggest that most homes have some issues with the legality of electrical works.. If the Insurance Co. could find a link between the claim and the illegal work, then that's one thing, but if no connection, then I can't see how they could ... A. Know there was illegal work, and B. Reject the claim..
Who keeps a record of what sparkie did what work..? ( Now a solar power plane - that's a different matter )

PS - I kinda doubt that any energy retailer would have much chance of taking action against "Inappropriate" power usage.. as distinct from ILLEGAL usage, which would come under Common Law theft..
ie.. I can't see a court wasting time on electrical consumption at a wrong rate.. :roll:
If we can't determine what is clear cut, then how would a Court hold a transgressor, guilty..
( Now, theft of power - that is different.. eg. bypassing the meter )
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
2 x CMS2000 (fan cooled) GCI and SE 170W panels
1.7kW First Solar/Outback Island circuit - Peak Replacement Power
Governments won't save the world :-) They will just TAX it :-(
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Re: Storage from Off Peak Usage in Peak

Postby FarmerJohn » Thu Jun 20, 2013 1:20 pm

Tracker wrote:Who keeps a record of what sparkie did what work..? ( Now a solar power plane - that's a different matter )


In NSW its the regional inspectors; though I forgot what the name of the office is.

They get a copy of every single compliance cert written by a sparkie and given to the customer for each item of work that they do - and they have to issue the certificate. Even if it was a trivial job (run new wire from DB to Kitchen for new electric cooker) a certificate is issued to the end user and a copy goes to the inspectors. In theory they can inspect any work item covered that way. There is a paper trail.

When I had the sparkie do the TOU meter, an inspector turned up unannounced three weeks later and inspected it. When I quizzed the sparkie, he told me how the system worked. Later when the same sparkie put my generator change over switch in the DB, it was tagged out and I was told that I couldn't even use it until and inspector got of his **** and finally managed to inspect it nearly two months later. Stuff like that makes me mad, but its a game we have to play right now because the penalty for not playing by the rules is costly. If you pay a lot for insurance, why make it easy for them to escape payments if it ever were necessary?

ASIO probably have us all tagged as a rebels now :)
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Re: Storage from Off Peak Usage in Peak

Postby Majik » Thu Jun 20, 2013 5:02 pm

For those interested I have modified my site www.solar-cell-panels.com as per Tracker's suggestions. Much appreciated. Now looking to add information to the site on a heliostat for lighting, but that is likely a week away. I had better check for any information on heliostats in the Energy Matters Forums. Best wishes, Majik
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Re: Storage from Off Peak Usage in Peak

Postby Smurf1976 » Thu Jun 20, 2013 10:34 pm

So far as an electricity distributor is concerned, there is no reason to oppose someone connecting a load to a dedicated off-peak circuit provided that:

1. There is no "changeover switch" of any kind which permits the device to also operate at peak times, thus defeating the intent of dedicated off-peak tariffs.

2. That there is no duplication of the appliance. Eg an air-conditioner wired to off-peak with a second, completely separate, air-conditioner installed in the same room for use when the off-peak supply is switched off. There would be no issue if you had, say, a gas space heater operating alternately with an electric one, but not if the second device is electric on the normal tariff.

3. That the load itself is reasonably economic to supply. That is, a good power factor and reasonable management of spikes in demand.

Meet those criteria and the distributor should be happy at least in theory. In Qld they promote off-peak quite aggressively and you can connect pretty much anything to it as long as it's hard wired. Other states don't push it as hard, but it's still there.

In Tasmania, battery charging is specifically stated as a possible (acceptable) use of the off-peak supply. That said, you'd have to hard wire the battery charger to the mains since off peak socket outlets (power points / GPO's) are not allowed (and haven't been allowed in new installations for 30 years although quite a few houses still have them).

In Qld it's possible to have off peak as the only source of supply from the grid if you want to and the intended usage is specifically stated as back-up supply to a primarily off-grid system. That is, you have an off-grid system but use off-peak (only) power from the grid to supplement it. You pay very little in connection charges for this option.

In Tas you can only have off-peak in addition to the main tariff, so as to ensure that everyone pays the daily supply charges. That said, there is nothing to say that you have to consume any energy on the normal tariff, only that you must have it installed if you also want off-peak.

I have the hot water (heat pump), dishwasher and clothes dryer all on off-peak (and all hard wired). It's on 10 hours overnight plus 2.5 hours of an afternoon so it's generally no hassle.

My mother does the same, although her house is from the era when off-peak GPO's were allowed so the dishwasher and dryer are just plugged in (and the hot water is just an ordinary off-peak electric system). She used to have a chest freezer on it too many years ago and it worked just fine.

At work we have a fully concrete "bunker" as a workshop. One of those places that stays cold even when it's in the high 30's outside. In Winter we heat it with a 4 kW heater on the off-peak meter which is simply left running, so that's 50 kWh per day. It's not hot, but it's not freezing either. It does the job.
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