Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

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Re: Load Dumping.. how it helps planning an integrated system..

Postby davidg » Thu Jun 20, 2013 4:39 pm

Tracker wrote:But I still wonder if it is not better to use that SSR, to drop out a solar system itself.. assuming we have various PV systems, AC-Coupled ... Dropping power to an SSR would instantly kill that solar power, and it could then cycle on and off (60Sec) doing start ups and then drop out again.


It's funny you mentioned it, the same system in remote NSW has that has "stove element diversion load" also has that as well just in case for the inverter, and it does work, however it does not offer "fine power control" For generic inverters that cannot be controlled any other way, a diversion load offers that fine power control that might be dificult to acheive otherwise.
(Really only counts where generic GCInverters are involved)

So for DIY, a cheap voltage monitoring circuit and an SSR or 2 some cheap elements and thats about it.
Suggested DIY costs roughly $100 to $150 depending on whether new or secondhand elements and size of diversion needed.

For me with 2 x dual hot water services (700 Litres), additonal heating elements & SSR's. It worked out to approx $500.00, thats pretty cheap, I should windup with a lot of hot water to boot :lol:
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby davidg » Thu Jun 20, 2013 5:03 pm

franks wrote:Will change to a AC load dump, use a hard wired 1500 watt ceramic heater element.

Question is the AUX signal simply an on/off digital switch?

I hope it's not an electro-mechanical relay because they don't last very long doing this type of work. Digital switching, needs power from somewhere to support an SSR on/off functions, just make sure the SSR has a suitably sized heatsink, SSR's typically need between 3-32Vdc to work.

If it's an electromechanical relay you could remove it, use the power/voltage directly to drive the SSR, they only draw a few milli-amps much lower than a coil, low cost SSR's switching rate is about 10ms.
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby franks » Thu Jun 20, 2013 6:35 pm

Control is a +12V aux output from charge reg and inverter charger, will drive a 25 amp opto isolated solid state relay. I have used the same aux output to drive power mosfets switching dump loads as part of a abondoned wind turbine project.
Its mentioned the aux output supports PWM switching assume a rapid rate.
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby davidg » Thu Jun 20, 2013 7:50 pm

franks wrote: will drive a 25 amp opto isolated solid state relay.Its mentioned the aux output supports PWM switching assume a rapid rate.

If it will drive an SSR 25A it'll drive a 100A version (7.5 to 11ma) as well. 8-) Cool easy result for you. ;)
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby Tracker » Tue Aug 20, 2013 3:12 pm

.
Every now and then I come across a reference to Invertek and Rich Electrics..
The Rich Electrics inverter system seems pretty comprehensive..
http://www.richelectric.com.au/

and yet I have never seen anyone commenting on the package.. Good or Bad.. :roll:

Charge Controllers,
Solar GT Inverters,
Energy Management Systems..
AC-Transfer Switches

( Yes , likely all included within an SP-Pro --- But we are considering OPTIONS )

These SolarWorx Grid-Tie inverters differ from most Grid-Tie inverters currently on the market, as they allow you to feed power back into the grid either directly from your solar panel array, or feed power back into the grid from a battery bank that is charged externally by your solar array or other renewable source using an external solar charge controller. This provides a level of flexibility rarely seen with grid-tie inverters on the market, as it easily allows you to combine the government sponsorship of a grid-tie system with the full power management and backup power capabilities of our fantastic SuperCombi and CombiPlus systems.


....it allows you to easily connected to pre-existing battery based systems, or gives you the ability to add multiple renewable power sources such as wind and hydro, or even add an advanced power management system such as a SuperCombi or CombiPlus to provide full blackout and power backup protection......


What are they like..?
..
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby Gordon-Loomberah » Tue Aug 20, 2013 4:14 pm

Tracker wrote:...they allow you to feed power back into the grid ... from a battery bank that is charged externally by your solar array or other renewable source using an external solar charge controller.
...
What are they like..?


Illegal, I would have thought, unless you are now allowed to sell energy to the grid from batteries. That may come in the future, or else I have missed the announcement where it was declared to be ok.
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby davidg » Tue Aug 20, 2013 5:36 pm

Gordon-Loomberah wrote:Illegal, I would have thought, unless you are now allowed to sell energy to the grid from batteries.

Not completely true. To export from batteries alone by default your mostly correct, an interesting thing and a sort of optional extra for the SP-pro is PCM addtion, that allows the SP-pro to export battery power but under distribution company control.

I also have seen but I did not install an SP-Pro with a DC-Coupled Solar array connected to battery bank that exports excess power generated, it does not export battery power only the excess solar power produced. mind you when clouds cover it gently ramps down compared to a straight GCI which drops of almost instantly.

Xantrex can do it as well. I suppose a few others could as well. SMA I don't know.
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby Gordon-Loomberah » Tue Aug 20, 2013 6:06 pm

Yes, exporting excess after the batteries are charged is certainly ok, Outback gear can do it as well, and I suppose some of the Latronics range can do it too. I have heard there are some trials exporting from batteries, for load smoothing, but I dont think it is something the average domestic installation is going to be allowed to do under normal circumstances.
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby davidg » Tue Aug 20, 2013 6:23 pm

Gordon-Loomberah wrote:but I dont think it is something the average domestic installation is going to be allowed to do under normal circumstances.

Magellan Power in WA has produced a unit for the "domestic" market, Horizon power in WA has listed tham as unit required for just such a use on their small regional networks, which are at "Solar capacity" for want of a batter way to put it.

The ramping / smoothing system, allows the big Diesel Generators that run those small grids to "ramp up" gently the batteries provide the smoothing and tamper down after or over a certain period of time when the sun disappears from the arrays Visa versa when it comes back, so that the shock load to the generator is not there, I would not like to buy one at the moment but they do exist.

They connect on the DC side of the inverter monitor the power being produced either provide power or absorb power as the sun varies the batteries involved are Lithium I would suppose LiFePO4 type. 8-)
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Re: Going Off-Grid.. AC / DC Coupling - What, How, Why - A Plan?

Postby Tracker » Tue Aug 20, 2013 9:14 pm

..
It is ALL a case of what is practical, Possible and perhaps prohibited..
Obviously that feature of the RICH-Electric system (grid Feed from Battery), WOULD be generally frowned upon (ILLEGAL), but that was a quote from their pages..

As mentioned many times, the Latronics Inverter PVE1200/2500, legally works with batteries..
They ONLY GCI when the battery reaches FLOAT and then drops out, so a fully charged battery , with loads of PV, can GCI that extra power and help the grid..
When you see the PVE1200 on ebay for 300 bucks, it can be a VERY good idea.. Beats the hell out of Dump-Loads..

but, back to the question - for anyone with experience - How does the Rich-Electric stuff stand up..
I have heard NOTHING about them, and Nothing is good, as we only ever hear of the BAD..
I am not suggesting an interest, just wishing to exclude or include different options aka "Plans"..

GRID connect - as valuable as Gold... Hmmm .. that depends who is paying the monthly fees..
I think that IF you have got to the point where you are actually self sufficient, then cutting the tether to the MotherShip power, becomes VERY attractive.. It just adds that extra complexity of WHAT IF you have super crap weather, and have to start the GenSet... I just dont see it as an issue, if it happens a few times a year...

I know that Soljin will say that the likes of ME ( or US ) will force general power bills up, because there will be fewer paying for the Golden-Poles and wires.. BUT Stiff-Shirt to that... :lol:

KOGAN showed that they could sell a mobile phone service at a fair price, and the BIG boys did not like the loss of business/profit - and so cut them off.... Now, NO cheap phone plan..
With Electricity - They will have nothing to cut off for ME... Just put a massive stanchion in the street to shade the house.. :lol:

3kWH a day - My bloody coffee maker would chew that up.. :roll: ..... :mrgreen:
..
.
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