Solar panel recommendation again please!

[Chris_Robb]

Thanks Rupert but my boat is on a swinging mooring and I try to avoid marinas where possible...more of a town quay/trots/anchor/visitors mooring kinda guy. And if I was in a marina I'd probably just run the coolbox off 240v or plug my battery charger in. Nice bit of kit though, G&Ts without ice or sliced lime is a just plain wrong!

OK so I think it's going to be a case of measure the available space, buy the biggest panels I can without breaking the bank and take it from there...perhaps on a smaller boat with limited space for panels I should be looking at a second alternator or some clever charging in the engine department, and just rely on the panels to keep the battery topped up when not in use.

I did have some suitable space for hard panels but after having converted to coach roof winching (much more important!) that's not an option now as there's string everywhere!

Ian, - you mentioned a second alternator - but if you have not got an alternator charge controller, then that perhaps should be the first thing to do, which would at least make the maximum use of your existing alternator.

Which to choose? Sterling or one of the many others. You need to determine your charging voltages as they are now at the battery, you should see 14.4 when they are well charged - if they are dawdling around 13.5v then you are not charging at all well and wasting your time (and the engines!)

Battery capacity should also be looked at, its much easier to get charge in to 2 x 100 amp batteries than just one.

I also found that by doubling up my alternator to battery supply cables, I substantially increased my charge rate. (but I did up my alternator size so was underspec.

No one thing will necessarily solve your problems, it will be a combination of many. Also not using unnecessary electrical items - the AIS transponder for instance may use a lot - so just cross channel.

You have the BM1 battery monitor - its a very useful piece of kit to understand consumption and charge rate.

 

[jordanbasset]

Tperhaps on a smaller boat with limited space for panels I should be looking at a second alternator or some clever charging in the engine department, and just rely on the panels to keep the battery topped up when not in use.

Have a look at this
http://www.adverc.co.uk/product/12
We got one for our boat (prior getting solar panels) and it worked well. Also good service from the company

 

[vyv_cox]

Waeco 18l compressor coolbox continuously (500mA on average in UK summer)

That's an amazingly low consumption. Waeco say it takes 35 watts average, which I take to mean over a period that includes cycling on and off. How do you manage with so little?

 

[robertj]

Ok, I really need to get my solar panels ordered before this "summer's" cruise. Looking at other smaller boats, I've decided the best strategy will be 2 panels, on top of the sprayhood, held in place by bungee and clips, easily demountable for dropping the hood or silly weather. I'm looking for personal recomendations if possible. I'm afraid I havent done any of the "sums" re power, but let's say worse case scenario I could be running:

CP180 plotter
VHF Rx
ST1000 tiller pilot
NASA clipper duet
NASA AIS Radar
NASA GPS repeater
Tack Tick Wind (12v, not solar)
A phone or ipad on charge
12v camping style coolbox
Tricolour
BM1 battery monitor
Base model Pilot gas sniffer
Occasional Sony car stereo use

The above scenario would be very rare TBH (unlikely to have the stereo on at night) and the longest single passage realistically I will be doing will be cross channel. I understand the draw from the NASA instruments and sniffer will be very minimal. No water pumps, showers, TVs or electric windlasses on board. I am in the process of swapping out cabin lighting for LEDs and will change the tric too next time I am up that way!

Am I right in saying 2 panels are better than one at the lower end, as they are less susceptible to shadows? I have a voltage regulator, can I wire both panels to one?

The panels need to be reasonable value, not looking for ocean spec here, semi flexible, fairly tough, and with eyelets or similar for rope/bungee mounting. Area approx 2'x1 each.

Any recommendations chaps?

forget the wind generator they are not that good.
What I forgot to take into account is where do you get your hot water from?
If its from the engine forget the whole lot, fit a high output alternator/smart controller and add batteries.

 

[AngusMcDoon]

That's an amazingly low consumption. Waeco say it takes 35 watts average, which I take to mean over a period that includes cycling on and off. How do you manage with so little?

The 35W is when the compressor is running, not the average over cycling. I try to open it only 2 or 3 times a day. I have a fridge thermometer and set the temperature to 6 degrees. Other users I've spoken to seem to get similar low consumption by taking care.

The downside is that the internal volume is only 18 litres.

 

[vyv_cox]

Our fridge is 65 litre capacity, front opening, run 24 hours per day in Greece. The temperature at the chart table, where I am writing this is 31C, just a few feet from the fridge.

We originally had two domestic batteries, both 110 Ah, with the same 125 watts of solar panel. On many mornings the voltage delivered was down to 12.0 or even slightly less on occasion. We then added a third domestic battery of the same size. Typical morning voltages are now 12.4 or even 12.5, even after four or five days without running the engine. A most worthwhile addition.

 

[Iain C]

forget the wind generator they are not that good.
What I forgot to take into account is where do you get your hot water from?
If its from the engine forget the whole lot, fit a high output alternator/smart controller and add batteries.

Ha ha! The kettle on the gas stove (welcome to my world!). Oh, and to wash hands I tend to lean over the stern and use the exhaust flow if the engine is running!

And to also lower the tone from a few other posts, the AIS radar is a small NASA box which takes minimal power, it just takes a feed from the plotter and VHF to plot ships on a monochrome LCD screen. It's not a transponder, or a radar!

She's a 40 year old 27 foot Sabre, nothing posh!

 

[Pete7]

She's a 40 year old 27 foot Sabre, nothing posh!

au contraire, if you are sat on the beach watching the posh yachties sailing up and and down the Solent

Anyway, back to Solar http://www.ybw.com/forums/showthread.php?t=316239&highlight=solar

 

[Chris_Robb]

Ha ha! The kettle on the gas stove (welcome to my world!). Oh, and to wash hands I tend to lean over the stern and use the exhaust flow if the engine is running!

And to also lower the tone from a few other posts, the AIS radar is a small NASA box which takes minimal power, it just takes a feed from the plotter and VHF to plot ships on a monochrome LCD screen. It's not a transponder, or a radar!

She's a 40 year old 27 foot Sabre, nothing posh!

Proper sailer.....
So just start with your engine charging - get that right, then add another battery(if room), then think about solar.

Stay Cool