What solar panel to buy?

[gulfbreez]

Hi,


Looking for advise on the best wattage solar panel to power a 12 inch tv (designed for boats) Nav lights. Basic instruments, VHF and charging phone once and a while with cig lighter on board. At the moment I have one deep cycle 12v marine battery on board. I would perfer to just buy one solar panel.



Im looking at this seller, im in the UK.



https://www.ebay.co.uk/itm/252394102....N36.S1.R1.TR9

[Pete7]

I have moved the thread to the electrical forum.

Have you done a calculation on how much power you will need both at anchor and underway? if so what are the figures? because this will dictate or at least guide you to the size of panel and battery bank.

There are quite a few other posts in this forum on how to calculate your daily needs if you need help.

Pete

[gulfbreez]

No I have not, but I will search the forums for that, do you have a direct link to a post?

[thomm225]

You can start by adding up all the amperage the electronics, lights etc draw on your boat

If you don't want to buy a panel or panels and batteries large enough to power everything you'll have to cut corners some place. Less lighting, computer vs a TV etc or less TV watching...…

Example: I have two 12 Volt batteries in parallel powering my lights, fan, depth, VHF, GPS, 400 Hz inverter, autopilot, drill when needed, computer when needed, etc

The batteries are being charged by 65-85 watts of solar depending on whether or not I have my 20 watt panel out or not. Usually I have it out (out of the lazarette) when anchored. My controller is a 20 A PWM I bought for $18.00 on Amazon.

The panels are hooked up in parallel.....which means both are hooked directly to the controller

[2big2small]

The simple answer is: as much as you can fit.

The complex answer requires far more information from you:
Which latitudes and which seasons do you sail in? Which climate (how often is it overcast or raining)? Where do you intend to install the panel(s) and are they meant to be permanent, or fitted on demand, will they be on swivels to track the sun, etc? Can you still fit in a travel lift with the intended installation? Plus obviously what others have asked: how much your daily power need is. How often do you get to shore power? And so forth.

Usually, after spending several days calculating and thinking things out, the answer will still be: as much as you can fit.

[thomm225]

To start you may want to at least have two 12 volt deep cycle batteries hooked up in parallel then you may be able to get by with 65-100 watts worth of panels, and as I said before, you may have to cut corners here and there depending on the various circumstances.

I saw one 12 volt TV that only had a current draw of 25 watts.

You will learn for example to turn off all electronics, lights etc when not in use even while sailing ........again when necessary

[Pete7]

Originally Posted by gulfbreez

Hi,

Im looking at this seller, im in the UK.

https://www.ebay.co.uk/itm/252394102....N36.S1.R1.TR9

The listing says "no collections" so he could be just a box seller, selling stock and ordering it from a main supplier to be delivered to you. The address looks like a residential house.

They are Polycrystaline, not the best. Try for monocrystaline. I have used these folks twice now and always delivered without a problem.

https://www.photonicuniverse.com/

GulfB you haven't mentioned a fridge? If this is a future possibility you need to add this to the list.

So in the UK summer with fridge, lights, tv and laptop we used 30ah per day. We could make this up with a 80w and 30w solar panel if the sun shined. When it rained for more than a couple of days we needed the engine to help charge especially if we ran the heating which added another 30ah during the night. We have now changed to 150 + 30ah panels.

Suggest you look for 100w and somewhere to mount it. It looks big but no one on here ever said I have too much solar. This is worth a read:

http://www.cruisersforum.com/forums/...ts-179638.html

[kas_1611]

https://www.sunshinesolar.co.uk/prod...V/SSF100E.html

I got one of these to add to my 2x32w fully flex panels and have been seriously impressed by it's performance so far. I actually tie my panels on top of my bimini although these are designed to really be stuck on the coachroof. It has stood up to 40kt winds and torrential rain quite happily and gives me a good 7 amps at the monitor during the bulk of the daylight hours. Although admittedly I am in Greece.

I have 2x140amp-hr batts in parallel and a 20amp MPPT regulator which is enough to power my normal anchorage needs for up to 3 days without having to run the diesel or panic about warm beers

I'd steer clear of ebay for things like solar panels as you can't be sure of the quality or may not get any guarentee. They may also not be built to withstand the maritime environment so could fail from corrosion rapidly. Better to pay a little more to avoid problems in the long term.

[cottonsail]

The best pricing I've found is Sun Electric in Miami Fl. I bought 2 - 250 watt Sanyo panels for $127.50 each. That's .51 per watt. The only other advise is to get a MTTP controller.

[Pete7]

Originally Posted by cottonsail

The best pricing I've found is Sun Electric in Miami Fl. I bought 2 - 250 watt Sanyo panels for $127.50 each. That's .51 per watt. The only other advise is to get a MTTP controller.

He is in Wales on a 24ft yacht. Miami might be a bit ambitious.

Pete

[CharlzO]

Just for reference, I had a very similar load for my 26' previously - VHF and chartplotter on full time when on board, lighter plug for phones and an inverter that would power an LED TV and/or laptop, etc. I had two GC2 golf cart batteries, and a 100 watt panel on the stern rail. Never had an issue dropping down, and even on an overcast weekend, never struggled. Can probably all be had for a shade over $300 these days, depending on panel and controller. I've gone the same route for my current boat, though with a Victron 75/15 controller instead of the one that came with the panel (Was a Renogy 100 Poly kit that was about $140ish I think at the time).

[CdS2 Roland]

Hello,
Don't think to much. Install the biggest surface and the best efficience you can. Who can + can -.
Have a good day.

[thomm225]

If you're not a liveaboard, sometimes it's also fun to experiment as you grow your solar power

I bought my 65 watt panel from Solar BLVD for $76.00. I then bought a $12.00 PWM 10A Chinese Controller and ran like that for a few years.

At that time, I had the left over starting battery (from when the boat had a diesel) and a newly bought deep cycle battery in parallel. Not the best idea but they lasted 6 years

Now I have two deep cycle 12 volt batteries in parallel with 85 watts of solar (65 + 20) charging the batteries thru an $18.00 PWM Controller that has the float set at 13.7.

This controller has a digital readout

I usually check the batteries SOC by checking the voltage on the panel side of the controller. If it's upward of 18-20 volts, I know the batteries are pretty close to fully charged

Also, the solar and batteries are my only power source. My outboard does not have an alternator.

[hellosailor]

How big is your wallet?

You buy the biggest batteries you can, so you have power during a couple or three days of heavy overcast. And the biggest panel you can, so it can recharge the batteries during that one day you have sunlight.

Or, you figure out the electrical loads and say "Well, if I buy this much panel and battery, that will work most of the time, and I'll just go to the pub when it is overcast for three days in a row."

Really, it is a matter of wallet and math, there's no one right answer.

[a64pilot]

Another thing is to look for residential Solar installers around.
I bought some left over panels for .50c a watt, no tax, no shipping a few years ago.
They were left over from a job and the next job may want different panels etc, so they will sell the odd ones at cost just to get rid of them, their cost isn’t much, cause they order them by the pallet.
Of course they are usually bigger panels like 250 or maybe bigger now