pfromero said:
Aspendell said:
Paul
A couple things stand out to me now that I know you are planning on a real 6kw inverter with 2 - 24v packs in series...
Thanks for the confidence, but I just got off the Outback website, and although, its what I need, the Inverter/charger with distribution panel is costing more than my entire 21 panel solar system installed. Back to the drawing board....
8S will give you a nominal voltage of 29.6v and a peak voltage of 33.6v. Which in series will give you 59.2v to 67.2v on the high end. Most inverters can't handle this input. So be sure to check the inverter spec sheet before you get started. I'm going for 7S packs and I will still be a bit on the high side for a 48v inverter.
Maybe I'll be able to nail it with a he 24v packs ...awaiting word back from the (Chinese) mfg. PS how did you go with 7s packs? Can you provide a link?
Also, 6000w / 48v = 125 amps. So you would need a bare minimum of 6 of the packs you describe (2S/3P) just to be able to have a full 1C draw on each cell at max output (accounting for losses).
Aspendell, I think I need clarification on the 2s/3p nomenclature. In my drawing, I thought mine was 8s/20p
Awaiting your response,
Paul
Yes, I did short-hand my response. So some clarification is in order.
The Outback Radian GS 8048 Inverter/Charger will accept a very wide DC input range: 40-64vdc. This is a much wider range than most inverters. However with your 2 - 8s packs wired in series you would exceed this maximum if your packs were ever charged over about 75% of max capacity, and the charger would be unable to charge them to full capacity.
Your second question: Since you said your packs would be designed for 24v at 51 amps capacity, then you would need to wire 2 in series to give you the 48v needed for a 48v inverter. This would give you 48v at 51amps. But since you would need 48v at about 150 amps to generate the max capacity of 6000 Watts, you would need 3 such series packs in parallel to have the minimal amount of current to run this inverter. Hence, 2 in series by 3 in parallel = 6 packs like you described (2s/3p)
And keep in mind that if you go with a less efficient asian build inverter, you will need much more than this.
What I would suggest is going with the highest wattage True-Sinewave unit from the half-dozen or so Inverter manufacturers that have been around for 10 years or more. You would get much more value for your money than buying something of low quality (that will actually deliver less even though its rated 3X as high). So if you have to settle for 1500 watts right now, just be sure to get one that has something like
OutBacks FLEXgrid technology so that you can chain more together to increase your total wattage and even go to 240 or 480v 3 phase AC output later.
Real inverters just aren't made much over 3000 watts because this is about the max that 1 or 2 people can lift without a forklift :-/ Instead they chain together the 120 lb or so units to get the desired wattage. So if you see a 6kw asian unit that weighs 50lbs in shipping, run away very fast!
Hopefully that clarified my statements.
Unrelated: I just got back from a rare trip to town (I live pretty far out), and all I could find locally for fuse wire was some 24 and 30 gauge Craft wire from Walmart, LOL. I got 25 yards each of gold and silver spools. I don't know what they are made out of, so gonna call the company and do some testing now
Oh, I missed your question about my config 7s.
3x5 on eBay
4x5 on eBay
I paid $4 usd for 10 of the 3x5s and $4.70 for 10 of 4x5s, but have to wait forever for the free shipping from China of course.
I'd buy the ones being sold here in the forum if you need them in under 4 weeks.
So I connect the long 5 cell sides of these together to get 7x5, then attach another 7x5 behind it to give me 7x10 cells.
Then the rows of 10 will alternate + and - every other row (to minimize buss length).
This will give me a nominal voltage of 7 x 3.7v = 25.9v and a max voltage of 4.2v x 7 = 29.4v (at full charge)
And later when I put 2 packs in series I will have nominal (avg) voltage 51.8v and 58.8v at full charge of 4.2v per cell. All but the cheapest inverters will be able to handle this input voltage range.
http://www.ebay.com/itm/331976415700?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
