Solar Panels for long term battery charging

[kashurst]

My marina has "upgraded" to all new super smart 32 Amp shore power points, that you can control via your mobile phone.
Excellent! - small problem, from time to time the system gets reset and the power points don't seem to turn back on by themselves.

So far I seem to have avoided flat batteries as I disconnect everything, and I am usually on board at least every three months so a quick plug into shore power everything is ready to go.

Now though, life seems to be getting more complex so I am seriously considering fitting a solar panel on the coach roof in front of the flybridge helm.
I have 5 x 140Ah batteries in total and I am looking to essentially just keep them topped up whilst I am away, not to run anything of consequence.

Not sure what size to go far in terms of power (I am guessing @ 100W should easily do it) Boat is in the med so plenty of sunshine
Should I fit 2 solar panels for redundancy?
Anyone got any recommendations for manufacturer?
Are these bendy panels any good?
Do you glue them on or screw fix?

Thanks

 

[Jamie Dundee]

I was getting ~3a from a 100w semi flex through an MPPT controller in decent conditions, max 6a in bright sun midday. I’ve added an extra 50w panel as I want my fridge on when I’m away from my boat. Now getting max 9.5a, 4-5a generally in decent conditions. I use these 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine If I was doing it again I’d fit a 200w panel with 20a MPPT controller.

 

[Flyingspanner]

We use a GSM Power Status Monitor, which will communicate by SMS or phone up to 10 x key-holders . The system will monitor Low & High Pre-programmed Voltage (ideal for power failure, or solar panel monitors), it can also measure temperature and humidity, only thing to watch out is some PAYG SIM cards are only valid for a certain period before the credit expires. You can then call the marina to reset the trip

 

[longjohnsilver]

100w panel should do the job easily in Spain. I have 2 x 100w here in Uk and they keep 900 ah of batteries topped up and run a full sized fridge freezer all summer.

 

[Hurricane]

Where would you put the panels?
It is quite difficult to find somewhere large enough on a motorboat.
100w should be plenty to keep batteries topped up but not for much else.
I have 600w on my flybridge eyebrow and that definitely doesn't keep up with the boat's load - fridges etc

Don't forget that you need a solar controller between the panels and the batteries.
There are two types of controller - the MPPT (Maximum Power Point Transformer) ones are the best.
Victron have a neat solution.
Use one of their MPPT solar controllers and they also provide various electronic devices to connect to their Victron Remote Management (VRM) portal.
Once connected, you can then monitor your batteries using their web site.

I've just set up something similar using VictronConnect but not using VRM.
I can now remotely start my boat PC which has a Bluetooth connection to my Victron Solar MPPT controller.
The MPPT solar controller is always on and always connected to the batteries so I can remotely monitor my batteries.

I've just connected to the boat from home and this is the VictronConnect display right now.
Note that the panels aren't harvesting much because the batteries are full and the mains powered charger is also operating.