Backyard Aquaponics
A place to discuss aquaponics

Stuart there are often a few second hand unite available as soon as grid power is within cooie they connect reason to much hassle often you will find as areas develop they run power

I think that was definitely true but as electricity cost have gone up so much I'm not sure it still is true.

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FWIIW.. were I wanting to power an AP anything from solar, then I would go with the UPS idea, as it will give you the AC to run normal components.
A 24V or 48V device would be best...
You can add external batteries..... to make it cover longer periods of poor sun, and just a good MPPT charger with the panel(s)

My thinking.... you see SOOooo many commercial UPS systems being scrapped.. possibly zero cost..

Only remaining thing... to do the maths on power needs
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Well if you see any send them my way

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I have seen hundreds being torn apart for the metals there in..
If you are serious, I can go and check if any are being processed..
They will ask for a donation to cover the "value" of the scrap..

Some time back they had dozens of NIB units, only problem... they needed about 20 by 12V batteries... 10kW... NICE..

I would assume that anything over 1kW would be a good starter..
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It would need to be compatible with the hybrid system I'm envisaging.

G. has advised me to go for LiFePhosphate batteries because they are so efficient to charge and responsive to both charging and discharging. A problem I have with the Lead acid batteries is they you can't do either in a hurray which means to get your level of required draw you need lots more of them.

I am not sure whether this is correct but if you are running off grid you will also need to build in the power factor into your calculations. On grid in normal households they don't charge for this inefficiency but stand alone I would assume you would have to take this into account.
Gunagulla may be able to help with this.

I looked into UPS for a while but the only large ones I could get a hold of ran on fairly high DC voltages which meant a lot of batteries.

I'd generally advise against a UPS if you want maximum efficiency, as they have significant standby power usage. Much better to use an inverter, or inverter charger, and separate battery.

re Power Factor, not an issue if using DC powered pumps, but most good quality inverters can handle PFs well away from unity, just make sure the inverter is appropriately sized for the continuous kVA, not kW, load.

BWII, short answer : no
If doing a domestic supply system, I think you can still get the RECs (now known as Small-scale Technology Certificates (STCs)), but it would have to be installed by a CEC accredited installer, which would blow most, if not more than all, the credits you receive vs DIY.
In reality, I think they are really a licence to pollute for the fossil-fueled electicity industry, so if you want to be truly green, don't sell your STCs.
Read all about REC/STCs here: http://www.energymatters.com.au/carbon-trading/

The low frequency inverters also seem to have a reasonably high standby draw (if using a small battery bank)

This has nothing to do with this but when we put the inverter on an oscilliscope we get pure sine wave the grid however seems to clip the voltage ie flats on the top and bottom of the wave. At this stage we can't come up with a reasonable explanation as to why this is happening.

Low end inverters, as often found on ebay, imported from China, often have huge standby/no load energy use, and I would not recommend their use to anyone. They also have a short warranty, and from many reports, are rather unreliable and likely to let the magic smoke out at an inopportune moment.

Decent quality inverters typically have 10-30W (depends on size) ON, but no load, power usage, but if you have intermittent loads you can use standby, which checks for load every second or so with a pulse (~330V peak/230V RMS), with a much lower energy use.

OT Sleepe: what is the voltage clipped at- and what is the resulting RMS voltage? Are there any power saving/voltage reducing devices in use?

The voltage appears to be clipped at 240v not sure about RMS (I think that involves math) hz is 50. The clipping is at both points in the wave and exactly the same duration ie its a pure sine wave with a short flat top and bottom. We tried it on both houses (separate grid connects) with exactly the same result. I am unaware of any voltage reducing devices and at my place we turned everything off apart from some standby power items.
The only thing both houses have in common is that both are three phase connected.

The low frequency inverter is 3000w continuous can't remember the peak and pulls 5 amp at no load,its running off a 12v battery bank.

That sounds very strange... perhaps it is related to the ocsilloscope? Does it say RMS, or peak to peak anywhere in its specs? Are all 3 phases the same?

The Oz standard mains voltage is 230V RMS, which means on an oscilloscope waveform you should see the top and bottoms of the curve peaking around +/-325V, to give the correct RMS voltage. Of course not everyone is complying with the standard, and RMS voltages of around 260V are not that uncommon, particularly when you combine rooftop PV arrays with long undersized cables back to the transformer.




I see your problem it's partly due to the 1 and the 2 before the V That's a terrible waste of electrons, just being converted into heat. My Latronics ON with no load usage is 0.5A, and standby is just 60mA.

Thanks for that Gordon will get my mate to check it again, he plays with the oscilloscope.

Its also his inverter and he is the one testing the off the grid solar system; which is why I gave him 4 of my panels.

I grew up in New Guinea, and the last time I went back was ... thinking... calculating... guessing... 1984 (my original calculations told me it was the day I was born so I'm guessing there might be some error there) anyway...

In 1984 there was a big drought. Port Moresby was all hydro-electric. There were a lot of power outages and water restrictions. I think the water was on for two hours a day, and the power was out for a while each day randomly. Power was provided by a few commercial airliner DC9 engines (or similar (I dont know so I guess)) , but no doubt there were a few teething issues with the duct tape that stuck the prop shaft to the wet hydro equipment or something.... anyway, we had a generator that came on when the power went out because we were wealthy middle class folk, and I have to say, it felt really good to have that feeling of independence. In hindsight and with carbon emissions in mind, solar would have made me feel even better, but that feeling you get with owning your own power plant is awesome.

I bought a little $99 two stroke 240v generator from bunnings to run the electronics on our kiln when we lived in the hills in the hope of gaining that feeling some more for when people would irritatingly crash into power poles all the time and interrupt our work. Every time the power would go out I'd run out all excited to start the generator only to discover that by the time I'd drained the 2 year old fuel, cleaned the plug and finally got the thing started, the power would be back on.

Also, if the NBN roll-out gets past my suburb and moves onto the rest of the nation, there should be a shipload of telstra batteries going cheap as they are (obviously) of no use for a fibre based system.

It's probably worth checking for telstra batteries.

I think it's a good time to go off grid.

that post was roughly directed at Stuart and was dropped here because for some reason I was reading the last post of page 3 rather than the post before these.

Sorry if I confuse