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gotwind
Forum Admin
United Kingdom
936 Posts |
 Posted - 10/05/2008 : 21:11:54
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With my 55w panel @12v - the max current would be 4.6A into a battery.
I have some 50v 6A standard rectifier diodes in stock.
Is this enough of a safety margin, when used in a reverse current blocking diode situation?
Specifications:
Max. Average forward rectified current: 6A
Peak forward surge current: 400A
Max. DC reverse current: 5uA
Junction capacitance typ.: 150pF
Temperature range: -50 to +150C
http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=46413&doy=10m5#spec
Just checking, cheers.
Ben.
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steve121
Starting Member
USA
8 Posts |
Posted - 10/05/2008 : 21:35:29
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Hi Ben,
Maybe I'm doing it wrong, but I don't use diodes on my solar panels. The reason is, I heard that the diode will lower the imput voltage of the panel by 1/2 volt, and that the amount of electricity lost back at night from the battery to the panel is less than the 1/2 volt lost during charge time.
Anyhow that what I heard? |
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speo
Junior Member
Canada
113 Posts |
Posted - 11/05/2008 : 03:49:42
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Ben,
To me, it seems like 55W doesn't match with 4.6A
For a panel rated at 55W, I wouldn't expect more than 3.5A. If that's the case, I think your diodes are good enough.
I have a new Sharp solar panel rated 80W with a maximum of 4.6A. Occasionally, I saw 5A for few seconds, when the panel was oriented directly to the sun, at noon, in very good weather conditions. Other than those few times, when it was brand new (it might not be related with panel's age), it was not going above 4.5A
If you use a good controller, you don't need the diode. I have a C12 that cut's the connection to the panel when the voltage drops very low (when the sun goes down)
Speo
www.windpulse.com |
Edited by - speo on 11/05/2008 03:50:14 |
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fungus
Moderator
299 Posts |
Posted - 11/05/2008 : 10:08:04
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| steve; it basically makes no difference; solar panels are designed to have an open circuit voltage of around 20v, well above the level of a 12v battery, and this makes up for any losses etc in wiring, hot cells, diodes etc. The maximum power point is about 15-17v depending on conditions but they are designed to have the maximum power point above the battery level. Now solar panels are pretty much constant current devices and taking that 1/2 volt off doesn't affect the current into the battery at any real level. |
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super windy
Junior Member
217 Posts |
Posted - 11/05/2008 : 15:19:00
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good points there guys, I also have a 50watt panel brand new and the max it puts out is 3.5amps, what you can do is connect your meter while shading the panel then checking the amps and play with the angle of the panels I did this with my watts up meter and found out that the angle of the panel needed to be raised alit bit for maximum output for that time of year since winter you would have it higher than the summer since the "arc" of the sun is lower.
cheerio
super windy |
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ghurd
Junior Member
USA
313 Posts |
Posted - 12/05/2008 : 23:50:42
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The "Isc" amps will probably never be exceeded, except for a few seconds of cloud edge effect.
Unless the PV is a brand spaking new thin-film/amoprphous.
A 6A 50V is usually enough.
I make the leads of the diode able to carry heat to the wires...
Heavy solder, heavy wires, etc.
Don't parallel the diodes, unless one is enough for the Isc.
G-
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Topic |
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solar panel blocking diodes?
