Solar Panels & Storage

[Sooty Dog]

Hi, new to the forum and just had to finish my first season aboard early due to family issues at home. Do I need to do anything special with the solar panels before leaving the yacht on the hard. I have 300w fitted, feeding 320Ah AGM batteries controlled by a MPT300 (??). Should they be covered up or will the system look after itself? Thanks.

 

[Trident]

It will look after itself fine and keep everything topped up - just check if you have wet batteries that the water is topped up and they have some ventilation; if they're sealed or gel etc ignore them.

The controller will ensure the batteries don't over charge and dump any excess power generated to its heatsink.

 

[Glyka]

The controller will ensure the batteries don't over charge and dump any excess power generated to its heatsink.

Hopefully...

300W are a bit much for a small heatsink. Better leave something on. Batteries don't like to stay fully charged all the time. The issue is complicated and not a matter of an one-liner though

 

[temptress]

Your batteries will be fine. Worry about damp/mildew instead

 

[charles_reed]

Hopefully...

300W are a bit much for a small heatsink. Better leave something on. Batteries don't like to stay fully charged all the time. The issue is complicated and not a matter of an one-liner though

I've left my almost identical system, on through 5 Greek winters with no I'll effect - I fail to see where the "Heatsink" is relative.
For information the BZ 500 (designed for up to 500 amps) can be set for anything from 13.5 - 14.8v fot float. When system volts reach that point the PV panels are merely disconnected.

 

[RichardS]

Hopefully...

300W are a bit much for a small heatsink. Better leave something on. Batteries don't like to stay fully charged all the time. The issue is complicated and not a matter of an one-liner though

Depends what kind of battery you are talking about but lead acid batteries do benefit from being kept fully charged on a float voltage all the time. An intelligent regulator will do this correctly without overcharging.

Richard

 

[sailinglegend420]

..... The issue is complicated and not a matter of a one-liner though

So right! The OP doesn't say where he is, what controller he has, and is he leaving it for the whole winter?

You can get into the situation where the controller switches back into Absorption at 14.4v every day and stays there for say three hours, because that's how it's designed, and if this is repeated for six months in a very warm climate with NO battery temperature compensation then the batteries will dry out!

I heard of a guy with brand new Trojans who had to leave his boat in India during the summer and when he went back the batteries were totally dry!

The answer is to re-programme the charge controller to a lower Absorption voltage, say 14v, so that the batteries never get to the gassing voltage and so can't lose all their water.

 

[duncan99210]

We have about 200 watts of panels hooked up to 300 ah of batteries plus the starter battery. The controller simply switches off the panels when they are fully charged: we came back to the boat having switched off everything on board except the panels after six months to fully charged batteries.

 

[EdwardThirlwall]

I think the biggest issues with keeping your boat in self storage is really more of the motor and the damp (like what most of the other guys on here have said). Just make sure that she's dry and clean (especially the engine) before you put her in and you should be fine.