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Author Topic: 2kw, PV Panels For Solar Tracker, Please?  (Read 6622 times)
stephendv
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« Reply #15 on: October 20, 2012, 09:57:06 AM »

Sorry clockmanfr, hope you don't mind this discussion going waaaaaay off course Wink

All this MPPT gear is only necessary because the voltage is too low.?

The real purpose is to follow maximum power point of the panels as their voltage changes due to different temperatures.  In winter the voltage could be 10% higher than STC rating, with a normal controller this is simply ignored, but with an MPPT, the controller can adjust it's voltage to turn those extra V into power.  Being able to string panels at a higher voltage to reduce wire loss is just an added bonus Smiley

I had no idea that the big solar farms were working off 48vdc,,I will have to give them a call and explain where they are going wrong..

I was only talking about the off-grid inverters working at 48VDC!  The grid tied solar farms definitely work at much higher panel voltages > 400 VDC.  I came across a spanish company that makes high DC voltage off-grid inverters the other day, looks like interesting kit, takes batteries up to 250VDC: http://www.ingeteam.com/EN/ProductsandServices/Energy/Photovoltaic/Products.aspx?TIPO=PTD&ITEMID=11693&IDIOMA=EN&PRT=SBP&PRTID=2  and http://www.ingeteam.com/EN/ProductsandServices/Energy/Photovoltaic/Products.aspx?TIPO=PTD&ITEMID=22&IDIOMA=EN&PRT=SBP&PRTID=2

 On a more serious note,,I think that when you begin to use MPPT controllers you close other doors and complicate matters way beyond their value.
 The minute one has to pick up a laptop to set up a system,you can say you have just trebled the price of it.Systems should be easily understood and user friendly and not there to prove how intelligent and clever some folks are with pc,s Grin.Keep it simple,,reliable and user frinedly.?

Amen to that.  But I don't think MPPT controller contradict this.  With all 3 MPPT controllers I've worked with: morningstar, outback, midnite- all of them had an easy to setup default set of settings that you either did with dipswitches (morningstar), or by following the onscreen wizard (outback + classic).  No computer needed.  There's also something to be said for the additional features offered by these controllers, e.g. ending the absorb charge based on the charging amps instead of using a fixed time limit can help prevent battery overcharging.  Even setting a custom time for absorb is a nice feature to have instead of relying on the defaults that came with the controller.
Must confess I like pc's me  Grin so it's always nice when you can connect a controller up to a PC network.  But it's not essential.
                                                                          
« Last Edit: October 20, 2012, 12:12:15 PM by stephendv » Logged

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biff
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« Reply #16 on: October 20, 2012, 10:18:54 AM »

Yes Clockman,sorry about that,
                         I opened my mouth and my foot fell out.  But wait,! maybe Clockman has a story to tell about mppt controlers,?
                                                           Biff
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stephendv
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« Reply #17 on: October 20, 2012, 12:13:12 PM »

BTW biff, I am still curious why the off-grid market doesn't do higher than 48v DC?  There must be some reasons.
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clockmanFR
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« Reply #18 on: October 20, 2012, 12:48:17 PM »

Sam 123, Thanks for that. There are good deals, but i am trying to get individual 250w panels, as 8off, will be within my Solar trackers design capabilities for loadings and fastening down.

stephendv and biff, Yes no problem, Do carry On.

MPPT is a great big step forward.
For me its taking the 120v dc from my PV, PV is 150m from the Controller, and efficiently converting it down to the charging voltages for my 48v batteries.  Although the 56.6v Charge and  54.8v Float seem to wonder about a bit due to the temperature compensation which i find damned annoying and would rather it did not have. (biff how it converts it down? don't ask me, it just does, and it does not get to hot and does not waste much juice in doing so).

I think MPPT has great future but a few blasted bugs in The Morningstar Tristar MPPT 60 need ironing out, and i think this particular controller went to Market to early. I read your blog Stephen.!


Warning. I have seen every fault known to man regester on my Tristar MPPT 60 when no temp compensation sensors are connected. And i put a voltmeter on the pv side of the Controller and the Controller sometimes just drops out, scary the needle just drops to zero then to full in about a 20th of a second. So i would not use this on a wind turbine where a constant load is required, if not then the blades will go supersonic or just bust.!
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biff
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« Reply #19 on: October 20, 2012, 01:43:15 PM »

Hi Stephendv,
              The off-grid market does 120volt controllers and inverters and even 90volt Shocked.Our controllers are 120volt hybrid wind/solar.They are really handy to work at.They come with 2kw of resistor dump load which is simple to bypass to immersion heaters.Great for simple souls like myself.
                                                                               Biff
         
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Other-Power
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« Reply #20 on: October 24, 2012, 12:57:41 AM »

You should be able to get 0.50 a watt ex vat and shipping on the order you want, drop me PM, ill forward links.

Cheers

Jon
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« Reply #21 on: October 24, 2012, 08:11:42 AM »



I think MPPT has great future but a few blasted bugs in The Morningstar Tristar MPPT 60 need ironing out, and i think this particular controller went to Market to early.

I think ALL the 'off grid' MPPT controllers went on the market a little to early, only now do the chaps at Midnight Solar seem to be getting it right and they have a great pedigree. It's what I'd go for if buying one.

Cheers, Paul
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« Reply #22 on: October 24, 2012, 03:14:34 PM »

As far as i know , Morningstar is  not a newcomer  to MPPT and more experienced than others  , sure Midnite solar MPPT  had their apprenticeship  at Outback .....  Nice to own one (Outback MX 60), designed by Bob  Smiley
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stephendv
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« Reply #23 on: October 24, 2012, 03:22:36 PM »

Midnite have also published a comparison chart showing the efficiency of theirs and some of their competition: http://www.midnitesolar.com/pages/competitorComparison.php
Interestingly they say that they tested it against the Morningstar and that the results were "close"... and then they exclude the morningstar from the comparison table, which tells me that under their test conditions the morningstar did better.   Wink
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« Reply #24 on: October 24, 2012, 07:20:43 PM »

Thanks Jon,
Please do forward any links you have, the more the merrier, they all help.

Just had the Spanish Co return a costing, price for CS 250w at 0.60 per watt including Vat, but wait for it, Transport etc to My French Address is 249.  Angry

Ivan/Navitron has come back with some good deals, so will study, but its the 250w panels that are crucial to the design of the New PV Trackers, or other wise i would of snapped his hand off, as it were.

St-ruff at this rate they will be paying me to take them away,  extrahappy  I Live In Hope?
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« Reply #25 on: October 27, 2012, 11:04:37 PM »

All I know it you can get 10 x 250 watt type panels in the back of a Mk3 golf estate and then what ever else you can get in the trailer

Might be worth a drive to collect.

Cheers

Jon
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