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Forum Index : Solar : Upgrade existing solar system
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windy city Newbie  Joined: 19/02/2010 Location: AustraliaPosts: 8 |
I have a 2Kw system that produces 1.7 kw max, it has 12 X 175 watt panels. What I am wanting to know is can I replace 4 of the panels with 200 watt panels to bring up the out put closer to the max output of inverter? Or will there be a problem with the variance in Amps and voltage between the two panels? I started out with nothing... I still have most of it. |
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| neil0mac Senior Member  Joined: 26/12/2009 Location: AustraliaPosts: 210 |
Sadly, No. The remaining 175 watt panels will limit the output. (Weakest link idea.) But IF a 175W panel was bad or underperforming, then a 200 watt panel would bring the system 'back to specs'. |
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norcold Guru  Joined: 06/02/2011 Location: AustraliaPosts: 670 |
How they are wired to the regulator? if in banks and they probably are, would suggest just adding an extra bank (of 200w panels)if your regulator can handle the extra input. ie. my system has an Outback controller with 3 banks each having 6x130wX12v panels, each banks max voltage must not exceed 120v. This controller will handle 3000watts. Just check up your controllers specs. Have been playing with RE for many years and feel the story of mixing different wattage panels is just a story, as long as voltage and current limitations of controllers are considered. Probably have others experience go counter to this, so please keep us posted on what way you go. We come from the land downunder. Vic |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
I would think this is a normal grid connect where either the whole 12 are wired in series or 2 strings of 6 are direct connected to the grid inverter, it then MPPT tracks the the panels to try and get the best efficiency . You are finding out what they dont tell you , effectivly you have 2.1kW of solar , you might see it peak at that only a few times and usually when it is a cool day and the sun goes behind a cloud , the panels cool then the sun comes out and you reach peak output which soon drops off as panel temperature rises and de-rates PV output . Because they are 175W panels very rarely will they reach rated output. I would allow 10 ~ 15% de-rateing on the panels , 10% efficiency loss on the inverter , so you have lost 20~25% giving 1700W to 1500W on a good day . There could be a chance that you have a bad panel, as Neil has said which will affect the whole string. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| peter69_56 Newbie Joined: 11/10/2011 Location: AustraliaPosts: 2 |
So on a day that the ambient is 20 degrees C, and I have a system with 14 x 220 w Canadian Solar panels CS6P-220PE, and a Cleanenergy SPH30 3kw inverter. On a cloudless day will the system reach peak if the solar energy is available. I have worked out I need 772w/m2 to reach max panel output of 3080w. Do the panels heat up when generating or just due to solar radiation on the day along with ambient temperature. My issue is on these days I never make 3kw and I am assuming due to the inverter heating up to 70C as it limits then. I suspect its not rated correctly for Australian conditions and is a European inverter and rated for their cooler climates, hence the derating and significant overheating when the ambient conditions are resonable. I am concerned that in mid summer in 2 months time I will be significantly derated. I suspect the inverter supplier will try and blame the panels and say they are derating, when the ambient is at 16-20C. I think they dont start derating until they reach 45C. Panel shoudl generate 3080w and inverter cope with 3300w |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Pete Solar panels are usually rated at a mppt voltage and at 25C , every degC over that they derate . The graph is usually found on the back or if you have a brochure for the panel . I would also think there would be info if you google . Make sure you read the fine print nad be prepared to get confused The panels heat up because of the sun not because they are generating power , go and put your hand behind one in the middle of the day and you will see how hot the get. If your inverter is getting up to 70C , I would be thinking about some extra air flow, would help keep it cool but not make it deliver better efficeincy . I don't know what efficeincy the inverter makers but it is usually doctored to some degree. In winter they perform better because of the cool conditions but the peak solar hours are less and in summer they are less efficeint but the peak solar is longer so it all evens out . PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Just qualifying my post, my system with the 3 banks is a battery not grid tied system. Each bank has an individual circuit breaker that can be switched ie each banks output can be checked by switching them off individually. This allows me to know by regular checks of controllers readings a comparision of their performance they come up right on the money as per specs of panel manufactures Sharp(check is made midday on sunny days). This check last year showed a sudden drop in one bank, on close inspection internal visual degrading was found on a panel. Sharp replaced all panels under warranty, because they did this without me pressurising them to much I suspect that batch of panels had manufacturing defects. Maybe of further interest I have some panels that were manufactured approaching 30 years ago by Solarex and BP 40watt 60watt and 80watt that are wired in series together that run a solar bore pump(direct no battery) and have done so for many years thus my belief mixing panels can be successfull. These panels on last check still produce very close to original specs. Bore pumping is a very demanding application(60m head) and should a panel drop output in such a system water output would drop dramatically. We come from the land downunder. Vic |
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