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wirren...
wirren...

Posted: Mon Mar 22, 2010 8:10pm

Post Subject: Solar panel ... charge controller... fuse requirements.

Hi Tony, I will soon be wiring up my 2 x40W panels to a Steca 20amp controller. The panels came with some hefty cables which I am using. I believe you also have a Steca controller & am wondering if you introduced any fuses into your installation. If so what type of fuse fitting. I am not sure but I think the Steca may have fuses within its housing ??? Regards Mark.

Tony-B...
Tony-B...

Posted: Mon Mar 22, 2010 8:33pm

Post Subject: Solar panel ... charge controller... fuse requirements.

Mark, first of all fuses protect cables, not equipment and I am sure my Watt panel would not be capable of generating enough current to set fire to the cables between itself and the controller even if they suffered a dead short under high sun. In fact I think that the panel would self limit the current because the volatge would be "pulled down". I would be very happy for someone who really knows about solar equipment to comment on this statement. What will cause a fire is if the battery can supply a dead short on the cables between the controller and battery - especially as the they will probably bypass the master switch (this is allowed under the BSS being similar to burglar alarms, bilge pumps and car radio memory) so it is VITAL that you fuse those cables as close to the batteries as you reasonably can. However inside the a battery box with acid fumes is probably not a good idea. The fuse should be rated no higher than the capacity of the cables. Tony Brooks

wirren...
wirren...

Posted: Mon Mar 29, 2010 10:04am

Post Subject: Solar panel ... charge controller... fuse requirements.

Thanks for the info Tony. The cable supplied with the panels is 4mm (squared).I have ordered a midi fuse holder with a 30amp strip fuse which will be fitted in the area of the boats 12v distribution board, near the batteries. Is the 30amp fuse o.k. to protect the 4mm cable supplying the Steca unit.

Tony-B...
Tony-B...

Posted: Tue Mar 30, 2010 8:05am

Post Subject: Solar panel ... charge controller... fuse requirements.

Unfortunately I am on holiday so can not look anything up, however I do not know why you selected a 30 amp fuse. The system is unlikely to ever pass more than 7 amps. The cable was probably supplied as 4 sq mm conductor cross section (if that is what you mean and not 4mm diameter) to minimise voltdrop along its length. If it's 4 mm diameter then I need the conductor cross sectional area. If it is the CSA then the modern cable will probably carry 40 or 50 amps as long as it is run in free air. The older style cable with thicker insulation (and thus cable diameter) will carry just over 30 amps in free air so you will be OK. Tony Brooks

wirren...
wirren...

Posted: Tue Mar 30, 2010 9:33am

Post Subject: Solar panel ... charge controller... fuse requirements.

Thanks Tony, the cable is 4sq mm csa. I chose the 30amp fuse as it seems to be the smallest that can fit a midi fuse holder. The fuse is being used as you suggested earlier to protect the cable from a short circuit & not to protect the Steca unit. Hope you are enjoying your holiday. Regards, Mark.

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