Solar Panel Regulator Output?

[Tim Good]

Ok so I have a 40w panel going into a regulator and then directly to the battery via a fuse. If I put a volt meter across the panel before it goes to the regulator it's putting out about 21v. If I then put a voltmeter across the output from the regulators (I.e. the pos and neg going to the battery) there is no voltage.

Is that right? Will it only begin outputting when it knows it is connected to a battery?

If so then how long would you expect a 30w panel to take to charge an average battery if empty?

 

[Tony Cross]

Most solar regulators (that I've come across) require a battery connection to operate, they do actually draw a small amount of power. In fact all of the ones I've seen tell you to connect the battery connections before the solar panel connections. So yes, it will only output when connected to a battery.

Your 40w panel can probably output almost 3 Amps when in full unshaded sun. How long it will take to recharge the "flat" battery depends on it's capacity but even if you draw no power from the battery at all, it will take weeks to recharge an average one.

 

[Stemar]

Someone gave me a rule of thumb, that one can expect, in amp hours, 25% of the power of the panel in Watts, so you can expect your 40w panel to give around 10AH per day in summer in the UK, a lot less in winter. On that basis, it's going to take around 12 days to put 100AH into a battery, because charging isn't 100% efficient. In practice, it'll be more than that, because the charge rate slows down as the battery fills up.

You wouldn't be able to put 100AH back into a 100AH battery because, if you get it down to 0%, it'll be buggered, but if it's a 200AH battery that's down to 50%, I'd expect it to take at least a fortnight to get there or thereabouts.

 

[johnalison]

Although your arithmetic looks a bit depressing, a 40 watt panel can be very useful to a casual cruiser like myself. My panel is adequate for keeping my 200Amp/h of capacity fully charged in the winter, and for providing a useful contribution when cruising during a long day-sailing leg or at a mooring/anchorage with the fridge running.

 

[ColleyV8]

You haven't disconnected the batteries and left the solar plugged in to the regulator have you? Always unplug the panels, then the batteries, Reg can be fubar'd from the other way round.

 

[Tim Good]

You haven't disconnected the batteries and left the solar plugged in to the regulator have you?

Ummm urrrrr maybe.... Yes.

At the moment I'm just using it as a stand alone setup before I rig it all it so yes I left the regulator connected to the panel when stored inside the boat? Why is that a bad idea?

 

[ColleyV8]

This is from select solar, but all panel producers state the same

When disconnecting the solar panel, regulator and battery, take care to disconnect the panel from the regulator first, and then disconnect the regulator from the battery. When reconnecting, connect the regulator to the battery first, and then connect to the solar panel. This will avoid causing damage to the regulator.

Also, never short circuit the regulator

 

[Stemar]

Although your arithmetic looks a bit depressing, a 40 watt panel can be very useful to a casual cruiser like myself. My panel is adequate for keeping my 200Amp/h of capacity fully charged in the winter, and for providing a useful contribution when cruising during a long day-sailing leg or at a mooring/anchorage with the fridge running.

Absolutely. My 40w of panels mean I come down to a boat with fully charged batteries, and even after a weekend without running the engine and having the FM radio on most of my waking hours, I've still got 12.6V in the resting domestic battery, so the panels are pretty much keeping up with my consumption.

 

[Cardo]

This is from select solar, but all panel producers state the same


Also, never short circuit the regulator

My solar regulator stated to connect up the panels before inserting the fuse into the battery connection. Did it that way and all is well.

 

[ColleyV8]

Which Regulator, does it state connect to panels without battery connected, or just fuse disconnected, chances of forgetting fuse is in is high. If so, I may go for them in future in that case.

 

[Cardo]

Which Regulator, does it state connect to panels without battery connected, or just fuse disconnected, chances of forgetting fuse is in is high. If so, I may go for them in future in that case.

Mine is like this - http://www.ebay.co.uk/itm/High-effi...20919403536?pt=UK_Gadgets&hash=item1c275bac10

Installation instructions say to wire up battery leads, but leaving the fuse out. Then wire up solar panels. When ready, fit fuse and voila, hey presto, free juice!

 

[ColleyV8]

Still the same order though

Installation instructions say to wire up battery leads, ..... Then wire up solar panels

Ignoring fuse requirement

 

[Cardo]

Still the same order though Ignoring fuse requirement

Uhm.
But the battery leads do naught without a fuse. They may as well not be connected up, which, technically, they aren't. So until the fuse goes in, the solar panels are connected to the regulator, without this in turn being connected to the batteries.

 

[ColleyV8]

Hi, looked at the tracer manuals;

Before connecting the battery, measure the battery voltage. It must be over 9V to
power the controller. For 24V, the voltage must be greater than 18V to properly detect
a 24V battery. The 12/24V battery detection is automatic and the check is only
performed at start-up.
Wire an in-line fuse holder no more than 150mm from the battery positive
terminal. Do not insert a fuse at this time. Confirm the connection correct and then
turn on the power

Appears to me to be hook up battery first, with no fuse, then when connection is confirmed + to + - to - connect the fuse to power the unit

May be wrong but it is chinese.