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Forum Index : Solar : Different Voltage Solar Panels
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paul_mac1 Regular Member  Joined: 17/05/2010 Location: AustraliaPosts: 74 |
Hi Guys, I have a BP Solar 220w panel and was looking at joining another one together in parrallel, the only problem is my BP Solar is 28.9v max voltage which charges a 24v battey bank and goes thru a GTI, BUT the new one I am looking at is 37.26v max voltage, can they still be connected together and charge the 24v battery bank without damaging anything? Cheers, Paul |
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| Privatteer Newbie  Joined: 09/06/2012 Location: AustraliaPosts: 39 |
GTI is what? only reference I found in a quick search is a grid tie inverter. I assume they also have an amps mismatch. Depends partly on series wired or parallel. If the regulator can handle the higher voltage won't damage anything but you will probably get a substantial reduction in output due to the mismatch. |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Paul, more info required - what regulator? Also, for a nominal 24V panel the max voltages you quote appear a bit low to me. My sunpower 210W/24V panel has an open circuit voltage of about 44V. It is that open circuit voltage and your regulator's max input voltage specs (I use MPPT) you need to compare. If the grid tie thingie runs of your batteries if I got your message correctly,it only sees the battery voltage. Different size (but the same nominal voltage!) panels in parallel should be fine if they charge a battery via a suitable regulator. Klaus |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Sounds like you are looking at some of those panels listed on a Not so cheap auction site. For the same cost per watt ($0.80 - $1.00) you can get panels to match your current panels, and i would advise you to go that way, unless you want fruit salad by mixing apples and oranges. Although you can use mixed systems, but each different rated panel block will need its own MPPT controller. It can get messy so unless the new panels are free, be best to stick with the same rated panels as you have. Pete. [quote]GTI is what?[/quote] Yes it means "Grid Tied Inverter" you really do need to catch up on the lingo.  Sometimes it just works |
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| paul_mac1 Regular Member Joined: 17/05/2010 Location: AustraliaPosts: 74 |
Hi Tinker, Im using an MPPT 20amp auto switching (12-24v) controller. here's the Spec Sheet for my current panel, and here's the Spec Sheet for the new one I am looking at. Yes the panel charges the batteries then goes thru the GTI, because even though the inverter is 10.5v-28v it goes into fault mode when connected directly to the panel  it would save me alot of hassle if it was that simple.
Downwind, yes you would be right thinking they are the ones....shhhhhh, don't tell everyone 
Privateer, yes its a grid tied inverter. Cheers guys, Paul |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
[quote]shhhhhh, don't tell everyone [/quote] I think you are safe, they have been listing the panels for over a month or more, and dropping the price by around $5.00, it would seem no one wants to touch them.
10.5-28v GTI, that dont sound like an approved inverter. 
The simplest way to use the New panels would be to add a second GTI (suitable approved one)and string the new panels together (series/parallel)then that eliminates the need for a second MPPT and the battery. 1Kw Sonny Boy GTI was rather cheap here a few months back, it be worth having a look around. Pete. Sometimes it just works |
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| paul_mac1 Regular Member Joined: 17/05/2010 Location: AustraliaPosts: 74 |
I wonder why, they are listed as number 8 of the 10 most effecient panels on the market. The GTI is an ebay special, but its outlasted my other 2 blue GTI's from China  even though its probably made in the same factory
Paul |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
[quote]I wonder why, they are listed as number 8 of the 10 most efficient panels on the market. [/quote] Maybe because they are not so suitable to a general off grid battery system. Perhaps the price after you add the auction fees on, they are not cheap priced panels, just average priced to everywhere else on the market. If used for a GTI system then they need to be installed and signed off on by a approved / licenced installer, now you try to find one to sign off on a adhoc system you purchased from the back of a truck ....... good luck? To feed power into the grid without approval can be seen the same as theft of power by the utility. Im not going to get all "Nanny" over what you should and not do, or the equipment you use to do it with, just be warned it could bite you, and the more you shove into the grid the bigger the red flag it might attract. They use satellite images to check what solar you have installed over time and map it to your power demands if you attract attention to yourself. If you dont have a smart meter installed or the old black dial power meter you will be charged for what ever you put into the grid, as if it was power you used from the grid. The reason is the electronic meters (unless its a smart meter) record power both ways the same, and it dont know which way the current flowed except current flowed through the meter, and that is added to your bill, the dial meters run backwards so they still work as 1:1 meters. Many have been caught out thinking they are being credited for the power, but find out they have been charged for the power they fed to the grid 
Pete. Sometimes it just works |
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| Privatteer Newbie Joined: 09/06/2012 Location: AustraliaPosts: 39 |
Went straight past that since I thought he was referring to a model. Those panels are a very bad match. Unless I am having a total brain fart series wired you will end up with 2 panels performing at a rough equivalent to 155w each. Parallel wired a lot of the time the new panel will be under performing as it will be at a lower voltage than spec. If the volts do go above the 28.9vmax of the old panel then the old panel will not provide any power |
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| paul_mac1 Regular Member Joined: 17/05/2010 Location: AustraliaPosts: 74 |
Ok thanks for that guys. I'll be giving them a miss. Paul |
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| tomqu7 Senior Member  Joined: 09/11/2012 Location: AustraliaPosts: 168 |
does anyone know what this is I have 25 panels supposed to be 5 kw in 2 strings of 12 and 13 going into 5 kv macsolar inverter it- can take this in one string I have voltage of pv1 800 other string pv 2 400 pv1 1700 watts pv string 2 800 watts I have 4 rows of panels once the sparkie forgot to connect the the 2 halves ???? do u think this is problem missing one row of 4 panels |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Tom, Again your question makes no sense with what you have asked and the information given. Its a bit like will oranges and lemons make good fruit salad with 12 lemons and 13 oranges. What are the rating for each panel in volts and amps or watts. Information is tools to work with to give answers rather than oranges and lemons. Sometimes it just works |
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| tomqu7 Senior Member Joined: 09/11/2012 Location: AustraliaPosts: 168 |
I bought these panels in the early days when u could not buy anything from solarenergystore.com.au they were supposed to be 250 watts but turned out to be i think 200 watts in one pv string I have 1700 watts other pv string 800 watts volts 800 to400 supposed to be 5 kw so working at 2500 watts should work at 3000 watts or more if 5kw I can only equat to the one I have at home does 30 kw on a good day and is a 5 kw and works at 3800 watts at least on one day it got over 5000 watt |
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| tomqu7 Senior Member Joined: 09/11/2012 Location: AustraliaPosts: 168 |
they are supposed to be all the same panels infomon usa i received 5 replacement pANELS FROM SOLARENERGY STORE TO MAKE UP WATTAGE AFTER THE PANELS TURNED oUT TO BE 200 WATT THIS WAS A CASE AS PHILM SAID they stood around and thought what can we put on advertisement to sell panels |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Its still unclear what you are talking about or how this is setup. Are these PV strings all parallel connected, or do they go to an inverter with 2 isolated inputs. As it make little sense to have 2 different voltage strings. Also what inverter is in use here, because 800 volt seems awfully bloody high, and many inverters dont go above 550 volts max. To me something is cocked up here either you or your system or both. Sometimes it just works |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Ha Ha , "Something is cocked up "" LOL ,,, Don't stop ,,I'm falling off my perch cackling at this bloody funny story. Though ,,my English learning is taking a belting,.lol. Happy New Year Bruce. Bushboy |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
I;m starting to think this Guy Tommy is having a lend of you guys Bruce Bushboy |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
i dOUbT iT. yEs thE cHINglISH iS sUMtwaTT a liTtlE haRd tWo FOllOW, aND tHee infomon IS liKe tRyImG t0 rEEd a cHINeZe dAtA sHeEt. But you might be right Bruce. Sometimes it just works |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Yup, but he is a regular now and well on his way to becoming a guru. Mark Mark |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Looks like just clocking up flying hours to me. David M David M. |
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