Author Topic: pv array sizing  (Read 21543 times)

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Ronnn

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pv array sizing
« on: January 17, 2010, 01:38:19 PM »
 How much wattage would be right for an off grid application. I have about 600 to 700 watts of older pv already. 12 35 watt, 12v  arco dynosaurs @24 volts into a FX 60 and 8 six volt Solaex 65 watt pannels in series into a Flex Max 60 set to 24 volts. We have a gas fridge and cook stove, and a propane backup generator. We frequently have several macs running at the same time and sometimes a pc too. At times there is a small recording studio running with some tube gear going and a sixteen track recording mixer and solid state amps for the near field monitors. At times a mac and the pc and the studio are on for 4 or five hours during the day mostly. I don't really know how much all this draws. The mate has cute little light bulb Icons and doesn't know when a radio is on. The radio is an old Sony tuner amp with speakers from the 80s. It's not exactly a paragon of efficiency. I've seen .9 kw on the mate I guess it can recognise that much. But the resolution on this thing sucks for the price then charge for it. We are about to buy 10 Kyocera KC 130s to add to the system. Six of these will go on the two passive trackers that the 12 old arcos now occupy. The other four will be in a fixed array. There will be a 10 foot homebrew turbine added when I get the tower and blades ready. I figured I'd do the hard stuff first. Sorry if this isn't enough info to come up with a good answer. Oh yea we usually watch a movie at night.  It could be a video or DVD depending on what looks good. The Tv is old style 26" diagonal. There is an Onkyo thousand watt home theatre system tho I think that number is mostly hype. With the current setup this gets us to 25 volts or 24.8 if I haven't had the studio stuff on all day.


While we are here.... would there be any advantage to re wire the 8 six volt panels to 24 volts instead of leaving them in series. Wouldn't that give me more amps out of the Flex Max or is the 48 volts a better deal?


Ron

« Last Edit: January 17, 2010, 01:38:19 PM by (unknown) »

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Re: pv array sizing
« Reply #1 on: January 17, 2010, 05:48:25 PM »
Hi Ron --


As far as system sizing goes, you pretty much have to talk kilowatt hours, for both your usage and input, or no one will be able to help you with sizing.


You have two MPPT controllers that can take PV voltage up to 150 volts each. (Be careful of high voltage; use the Outback string calculating software online, it will likely tell you not to exceed 130v or so).


I would rewire both your arrays into strings of higher voltage.


And you'll likely need another controller -- you don't want to mix and match any PV panels into a single MPPT controller, as it will always track the worst performing array. I would personally get an inexpensive MPPT controller (the one from morningstar maybe) for the old Arcos, and use the 2 outback controllers for your new Kyocera string and the Solarex string.


DAN F

« Last Edit: January 17, 2010, 05:48:25 PM by ADMIN »

dnix71

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Re: pv array sizing
« Reply #2 on: January 17, 2010, 06:19:00 PM »
You haven't said anything about batteries. You want to triple the amount of power you can produce, but where will you put it?


How much are you paying for the Kyoceras? They seem to be popular these days.

« Last Edit: January 17, 2010, 06:19:00 PM by dnix71 »

richhagen

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Re: pv array sizing
« Reply #3 on: January 18, 2010, 12:32:49 AM »
Without climbing up on my cold roof to have a look, I want to say that the sticker on the back of my old 35 Watt Arco's says 50V max series string or something like that.  I have three sets of four in series on my system.  Mine are the 33 cell version with the screw stubs on the back.  Rich
« Last Edit: January 18, 2010, 12:32:49 AM by richhagen »
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Ronnn

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Re: pv array sizing
« Reply #4 on: January 18, 2010, 02:48:42 PM »
Thanks Dan, I was aware of not mixing the input to the mppts. I'll look into the Moriningstar. I also will need something with load diversion for the homebrew 10 foot turbine. But it will be a while before that one will fly. What's a good book to get up to speed on the new solar lingo and calculations. We installed all our stuff so long ago that I've forgotten nearly everything about all the formulas and calculations. It is so cool to have all these alt energy disiplines in one place. Thanks to all who make it possible.


Ron

« Last Edit: January 18, 2010, 02:48:42 PM by Ronnn »

Ronnn

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Re: pv array sizing
« Reply #5 on: January 18, 2010, 02:51:00 PM »
It's the Solarex that are in series.


Ron

« Last Edit: January 18, 2010, 02:51:00 PM by Ronnn »

Ronnn

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Re: pv array sizing
« Reply #6 on: January 18, 2010, 02:55:42 PM »
the batts are at the begining of the thread and I'm getting them for 484.00. Since I was given that quote they have gone up by 50 bux.


Ron

« Last Edit: January 18, 2010, 02:55:42 PM by Ronnn »

Ronnn

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Re: pv array sizing
« Reply #7 on: January 18, 2010, 02:57:26 PM »
that should have read I'm getting the KC 130s for 484. The batts were lots cheaper.


Ron

« Last Edit: January 18, 2010, 02:57:26 PM by Ronnn »

hydrosun

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Re: pv array sizing
« Reply #8 on: January 18, 2010, 04:33:37 PM »
Get an inexpensive killawatt meter and hook in up to the output of your inverter. That way you can see how much your average daily power usage is. Don't you have a amphour meter on the system now? How are you powering things now?  You need some meters to design the system and some meters to keep track of your battery after you get it running.

 I agree that the mate is not accurate enough to keep track of a system. It's mainly a way to program the inverter. Some systems I use my own mate to program the inverter and not leave one on. Unless you want to equalize or change something else it isn't needed.
« Last Edit: January 18, 2010, 04:33:37 PM by hydrosun »