Solar Panel Size

Submitted: Friday, Jul 11, 2003 at 17:51

ThreadID: 5935 Views:2068 Replies:2 FollowUps:3

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Member - NOBBY

Is there any difference in out put between two 40w panels and one 80w panel. I would rather two smaller panels than one large but not at the expense of out-put.

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Reply By: Glenno - Friday, Jul 11, 2003 at 18:04

Friday, Jul 11, 2003 at 18:04

The biggest advantage of two solar cells is if one is under the shade then the other one can still pump out power. With one big cell if you get part of it under a tree then the whole unit output. Unisolar is the exception to this (apparantly) however there have been a few posts on ther quality on dirt roads.

I havent looked at the wiring diagams however you may be able to rig them up so you pull 24V off them into regulator rather than 12V.

No doubt there are a few other beenfits others will point out.

If your in Brisbane i picked a 80W Kyocera up from AuSolar for the best price i could find in Brisbane. So give them a call if your in Birsvegas. The guy even dropped it over to my place for free.

Cheers,
Glenn.

AnswerID: 24724

Follow Up By: Member - NOBBY - Friday, Jul 11, 2003 at 18:13

Friday, Jul 11, 2003 at 18:13

Thanks Glenn , I am in Bris and will give them a ring on Monday for some prices.

FollowupID: 16626

Follow Up By: Glenno - Friday, Jul 11, 2003 at 18:47

Friday, Jul 11, 2003 at 18:47

No probs.

The guy is called Hans, and AU Solar is at Deception Bay.

He quoted me $710 for a 80W Kyocera. I had been quoted $745 from Solaronline + freight, and $820 from olbus at Rocklea.

I also picked up a Solarex Stecca 12A Reg at the same time.

Good luck

FollowupID: 16627

Follow Up By: joc45 - Saturday, Jul 12, 2003 at 12:57

Saturday, Jul 12, 2003 at 12:57

Hi Glenno,
The two panels you can set up with hinges to fold up more conveniently.
And as stated, if one panel goes into the shade, the other keeps going.The panels should be connected in parallel via separating diodes to stop volts being fed back onto the panel in the shade - these are usually already provided in the terminating box on each panel, but if not, are available from Jaycar, Altronics, etc. There is usually info supplied how to connect these diodes.
A small improvement can be made by using 5A shottky diodes, again avail from the above fairly cheaply. These have a smaller voltage drop than silicon diodes, but the improvement you may only notice around sunrise or sunset, when every volt counts.
Don't connect the 2 panels in series to your 12v system. The max voltage will hit over 40v, no load, (and you will pull no more current than one panel will, and will possibly overheat the panels).
Expect the output to drop during high temps by up to 30%. Chuck a bucket of water over the panels and see the output climb!
rgds
Gerry

FollowupID: 16663

Reply By: Member - John- Friday, Jul 11, 2003 at 21:16

Friday, Jul 11, 2003 at 21:16

Don't forget Nobby that the mfrs rated output from the panel, ie. 80W is nothing like what you actually get in practice. In Australian's conditions, particularly the nthn half you can generally expect to get about 55W out of an 80W panel and a similar ratio for any size panel. Mfrs play a game called "specsmanship", but that is another story.

When calculating how much energy you might collect for your batteries assume about 55W for an 80W panel.

In general 2 x 60W or 2x 80W panels will keep the usual stuff in a fourbies going, eg. a fridge and a light, etc.

Have fun! Solar is the way to go!

JohnS

AnswerID: 24735