New off grid home

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Re: New off grid home

Postby Cherokee Solar » Tue Jul 31, 2012 8:29 pm

Hi Kurt,

Sounds like a great idea for the tractor.

I installed the 24v LED flood light in the battery room on the off chance that the inverter wasn't operable and there was no mains power but battery power was available. Mind you, how I'd get in to the battery room with a 240v fire rated roller shutter is another story altogether... ;)

It works a treat and seems to be in a very rugged case. It also seems to be very good with large swings in voltage unlike the previous 24v CFL lamp which blew after not much usage when the voltage peaked at 28.8v. Grrr.

Much better than your tractor candle though! hehe! :D

Chris
Off grid solar + hot water. Heavily insulated + owner built flamezone house BAL-FZ. 300 mixed fruit trees + herbs + flowers + vegetables. Bees + heritage chickens. High up in the mountains north of Melbourne. http://ferngladefarm.blogspot.com.au/
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Re: New off grid home

Postby offgridQLD » Wed Aug 01, 2012 4:50 pm

Can anyone see any issue with wiring the the + side of the charge controller like the pics below. Im happy with the two 50A circuit breakers for the PV+ that are paralleled at the output and connected to PV+ of the charge controller.

Image

What I am not so sure I'm happy with is the Bat + going form Bat+ terminal of charge controller to the 125A fuse then from the fuse to the main battery + cable. Lets say I just wanted to isolate power to the charge controller I would have to pull down the main battery isolator that kills power to all three fuses. That would killing power to the inverter.Not a good thing when my wife is watching TV :lol:


I plan to completely remove the two 6A breakers ( red cross through them in pic) they were used just to power the old PL40S but didn't carry any high current due to they way the Pl40s are wired.

Am I on track thinking another isolator at the charge controllers max out rating to go between the bat+ and 125A fuse would be the go ?

While I'm talking isolators. DC vs AC Why the difference. My understand is its fine to use a AC isolator in a DC application. But you will have issues using a dc Isolator for a AC application?

Kurt
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Re: New off grid home

Postby Cherokee Solar » Wed Aug 01, 2012 9:44 pm

Hi Kurt,

Just for your interest, your current PL40 x 2 wiring should look like this:

Wiring.jpg


Regards

Chris
Off grid solar + hot water. Heavily insulated + owner built flamezone house BAL-FZ. 300 mixed fruit trees + herbs + flowers + vegetables. Bees + heritage chickens. High up in the mountains north of Melbourne. http://ferngladefarm.blogspot.com.au/
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Re: New off grid home

Postby offgridQLD » Wed Aug 01, 2012 10:45 pm

Yes that's about how mine are wired now other than anything to do with the PLA as (I don't have it). Although I do notice they are showing a Fuses on the Bat negative wire from the charge controller back to the battery.

Mine just runs a wire from the Bat- of each charge controller to a terminal block then from the block one heaver wire wire up to the external shunt in the inverter then a wire back down terminated to the main 250A fuse at the main DC (Battery) isolator unit. So given the (250A fuse..just to protect battery not controller) effectively no fusing on the negative side as far as the pl40 is concerned. other than the main battery isolator. All fusing/breakers for battery and PV in my system are on the possessive side.

Anyhow I am going to rip them both out . After some reading up on the outback and mid nite solar controllers . Along with some emails to the shop in the US that i intend to purchase it from (they sell both outback and midnite)I have decided on the Mid nite solar classic 150.I n the end it from what I could pick up the people behind the design of the outback have now moved on and created mid nite solar. So the classic 150 is all the good things from the outback but with a few extra features and specs that the outbacks fell short on. Pick it up 22 September so will have a crack at installing it on the 13th of Oct when I'm back In AU.

Kurt
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Re: New off grid home

Postby offgridQLD » Thu Aug 02, 2012 12:20 pm

I will just pick up one extra 90amp DC circuit breaker to slot onto the Din rail where the two low current 7amp Pl40 breakers are now. Keeps it looking neat then. Going through mid nite solars listings they seem to only sell there 90A in a panel mount and nothing that high in DIN mount. That's a shame as as there CB's look nice and are 100% duty cycle rated but it would be nice to keep all the breakers in the one box as I'm a neat freak when it comes to wiring a component layout.

I think it might be a general size limitation to DIN mount as 65 - 70A in a dc breaker as I cant seem so find much bigger in other brands to lots of AC though. No big deal if its is panel mount it is then.

Kurt
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Re: New off grid home

Postby offgridQLD » Tue Oct 15, 2013 3:54 pm

I didn't really want to start a new thread so I will tack this onto my original thread.

We spent the weekend at the off grid house . Charged our electric car 7kwh on Sat and pumped 14.5kwh into the house bank and then another 7kwh car charge on Sunday with 17.1kwh into the house bank . Both days we just ran our normal house loads. This is what we usually do most weekends and we make it to float or dam close to it each day doing this .

Now there is some shocking inefficiency with my system and the lead battery's so I have come accustomed to seeing tiny KWH AC numbers being consumed vs big KWH DC numbers being pumped in by the PV. Though things seems to have gone a bit silly.

Yesterday (not at the house so only base loads) I pumped 22.6kwh into my battery's :shock: and the voltage dropped lower than I have ever seen over night 49.8v by early morning. Then today again I have pumped 20.3kwh (not at the home again) into the bank by 3:42pm :shock: Now I might have had some small deficit from Sunday as I just charged my car mid morning then some clouds rolled in early afternoon so didn't quite reach float. But I would have just expected a extra kwh or two on Monday not the 43kwh I have pumped in over the two days. Considering my base loads are under 3kwh AC over 24hrs its not looking good.

Usually I can just swing my security camera around and see the live view of our homes AC kwh meter to see if any unexpected loads are on the system but my daughter was fiddling with it on the weekend and turned the meter to face the other direction :roll: Though we are reasonably pedantic about checking no loads are on the system before we go unless a pipe has burst and the water pump is flowing all the time. Though I suspect not.

I will see what the system dose over night regarding voltage I usually only see it drop to around 50.8v by early morning. I will see tomorrow regarding kwh in over the day but If I see numbers like 20kwh again I think its time for a mid week check and the lead could be having health issues:(.

Kurt.
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Re: New off grid home

Postby jimbo » Tue Oct 15, 2013 9:03 pm

What do you think the SOC was after yesterdays 22.6kw? What else did the midnite show?
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Re: New off grid home

Postby offgridQLD » Tue Oct 15, 2013 10:30 pm

It looks to have hit absorb around lunch time yesterday at around 17kwh and then just held that for 3hrs because it didn't reach end amps. By 5pm the sun is off the panels and the voltage drooped to around 51. Then it was a slow decline in voltage 48.9 at 4.50am today when the sun came out again.

Again today same story hit absorb voltage around lunch time at 16.6kwh and timed out after 3hrs of absorb , it never hit end amps.

Its crazy its pumping some serious power into the pack . Its like I am there welding and boiling water all day :?

Kurt
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Re: New off grid home

Postby jimbo » Tue Oct 15, 2013 10:37 pm

How many amps is the controller feeding the batteries just before 3 hours of absorb are over?
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Re: New off grid home

Postby Helipos » Tue Oct 15, 2013 10:56 pm

offgridQLD wrote:
While I'm talking isolators. DC vs AC Why the difference. My understand is its fine to use a AC isolator in a DC application. But you will have issues using a dc Isolator for a AC application?

Kurt


To answer your previous question a bit of an explanation is required.
Technically an isolator is a switch that operates with no current flowing through it. In a power system you open a circuit breaker to interrupt the current flow then you can open associated isolators to isolate the circuit. If your using an isolator in its intended form than yes a AC version will work for DC no problems.

However most people use an isolator to interrupt current flow. Here the use of AC rated equipment to break DC current flows is a very bad idea. Under heavy current flows, the arc that's created when opening the circuit will not self extinguish in a DC circuit because the voltage doesn't transition through 0V like it does for AC voltages. Thus you can get a sustained arc that doesn't self extinguish easily and is quite capable of burning your isolator to pieces.

As for your current problem I think you should take a trip out there with a multimeter to find your rather large parasitic load.

Cam
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