8x "Foldable" 300w Solar panel

[pdsman53]

Hi,
I have a 28ft Mustang boat (Sydney, Australia).
Since my wife passed away, I don't use it as much as I should (which I intend to rectify).
There are 2x-12v batteries on the boat....1x Engine cranking (1030 CCA RC 300) and 1x House Accessories (780 CCA RC 240).
In the past, if I didn't use it at regular intervals...the batteries, went flat.
Also, if I am out on it for a few days, I need to recharge them...due to the power requirements.
Therefore, I would like to put a Solar Panel on it....to (partly) cover both issues.

I don't really want to install a permanent "hard" framed unit...there's never enough space on boats, to do so.
I am considering purchasing an Ebay.....300w "foldable" Mono-Silicon 8x panel unit, that could be:-
1....stored on the boat (400mmx400mmx60mm).
2....be used to trickle charge the batteries, when sitting on the mooring.
3....provide some power to the batteries, without having to waste fuel (@ $2AUD/Litre) running the engine for a couple of hours every day (65amp alternator).

If I hook it up the "Controller" and wiring to the battery system permanently and then I could:-
A....fully open the panel and tie it down to the topside of the Bimini (roof cover), when boating for more than a couple of days.
or
B....."partially" open the foldable panel, so it is only partly exposed to the sun.....say 1 panel.

8x panels = 300w....that sounds to me, like 1x panel should provide 37.5w....which is ample power to trickle charge the batteries.

My query is:- Am I correct in my thinking and could this type of panel operate like this (partially open)???
Thanks in advance.

 

[axel44]

I had a similar problem with my 20' CC fishing boat that stays in the water all of
the time. Due to infrequent use and bilge pump running at times, the house battery
would drain down. My setup is similar to yours, cranking battery and house battery
but I put a Automatic Charging Relay (ACR) between them which allows the cranking battery
to charge while the boat is running and then switch over to charging the house battery when the
cranking battery is full. Long winded, sorry.

I permanently mounted a 20W panel to my TTop and installed the charge controller to trickle
charge the cranking battery which then kicks over to the house battery when full. The kit was about
$50 on amazon. So far, it has kept both batteries topped off nicely.

Axel44

 

[MichaelK]

A couple of important points. A panel laying flat on top of the bimini will lose a significant part of it's output. Don't expect to see the panel producing more than 25-50% if rated output, and 50% would be surprisingly good. Secondly, any shading whatsoever will kill output, so make sure that even little shadows, like a shroud shadow across the surface, are totally eliminated. A partially unfolded panel most likely will produce almost zero output. These details of course can be checked by you. Just use the amp function of a multimeter to measure the amperage output. Assume though that voltage more or less stays the same. Its the amperage in your case that will go up and down. BTW, I have a niece living in Adelaide, and I just love it there. If people weren't driving on the left side of the road, I'd think I was in California.

 

[pdsman53]

Hey guys.
Additional research revealed that...."amorphous" blankets, will still charge if partially covered.
I know it's the best solution, but I'm not sure I want to spend the extra $'s though.

Adelaide, is nice....but man, the temperatures go crazy, 43 deg C. for a week or so, in summer.

We drive on the left side....because the oncoming traffic, is on the 'right' (not wrong) side of the road.

I've travelled to 40 plus countries to date, but not the US.
If I do so, California will be on the list.....and like you guys, I'll then be driving on what's left of the road.
Cheers.

 

[tictag]

It sounds like adding solar, or perhaps a small wind turbine would be ideal solutions for you.

The removable/foldable type might be OK but at least consider researching the ruggedised panels designed for marine applications with the non-slip surfaces and are permanently installed. Their output is crap relative to a roof-mounted panels, for example, but they'll do just fine for trickle charging. Once installed, you're done; you can walk on them as if they were the deck.

Small wind turbines (e.g. 150W) are also pretty cheap and will keep you batteries topped up over Winter.

One consideration: if your batteries have been left discharged for long periods, they may well be knackered. Without specialised tools, the easiest method to test is to connect a a 12V bulb across a fully-charged battery and time how long it takes to discharge - re-charge immediately. If the bulb is say 15W, it will draw 1.25A at 12V (P = V x I) so it should last around 80 hours for a 100AH battery. For a variety of reasons, this isn't scientific! But if you're only getting, say ten hours, you know your battery is buggered. I did something similar for my batteries when I realised I had been overcharging them, my two brand-new 110AH batteries ended up with capacity of around 10AH each after just six months. Lesson learned.

 

[pdsman53]

Thanks Tictag,
I hadn't really thought about a wind generator!!
....but unlike Sailboats, these power boats are limited for that type of space (without running the risk of blowing the steaks, off the BBQ)......the Radar Arch, is already too busy and the bowsprit is too close to the anchoring/mooring ropes area....I can see it now..."headless body found, in water, after accident with overly powerful Wind Generator".
That's probably why, I have been leaning toward the practicality of a folding Solar panel (...not withstanding the inconvenience of setting it up and taking it down, each time I go out for a few days).
I considered, installing a 2kva petrol generator.....but how do you get away from the refuelling/noise/smell??

I'm currently considering updating my 1x 100Ah house battery, to 2x 135Ah....I need to check my space requirements. That, along with swapping out Halogen for LEDs (and a few other AMP hungry appliances), adding a trickle charging solar panel, using the boat more often during winter, that would probably alleviate most of my power issues....at least for the 2-3 day type outing.
Failing that.....I'll have to buy a new 'bucket'....I could then decommission the electric toilet.....just have to remember, which way the wind is blowing...when emptying the bucket.
Cheers.