Solar panel placement

Benny17441 · Mar 21, 2012

In my opinion solar panels are a passive way of generating electricity and are at their best in an unattended boat. If you are going to be cruising that means you will be spending more than a few hours aboard so it would be more convenient to fire up that Honda eu2000 and let the inboard battery charger do its thing. The output of a 15W solar panel is hardly worth the trouble of doing an installation especially if it is only a temporary one.

Stu Jackson · Mar 21, 2012

I agree with Benny, based on the size of your panel, and without knowing your daily load and house bank capacity.

Solar panels are NOT like wine, they do not improve with age and exposure.

If you're not using it, take it home or store it below.

Maine Sail · Mar 21, 2012

RECESS said:
I know this has been discussed ad nausium but there are a few considerations I wanted to ask about.

My Pearson 323 is kept in a marina with shore power all the time. The battery charger on the boat does a great job keeping the batteries charged without over charging. We are going to go on a week long cruis without going to marinas and this summer we are planning to cruis the Bahamas. So I ma going to install a 15W panel to charge the batteries while the boat is anchored. I will really only need the panel on the boat when cruising.

Should I create a bracket on the bimini that is easily removed? Or is a stern reail bracket better? I hate looking over my rail and having the view obstructed. I have a dodger that would interfer with the panel on deck.

Should I have a switch to disconnect the panel when I am running the engine or will the regulator take care of that anyway?

Is it a good idea to take the panel home when I have shore power available to allow the panel less exposure to the elements or do they age better if they are being used?

A 15W panel would take WEEKS to charge a decent house bank from 80% SOC to full... If you want to do some actual recharging then 80W and up is likely where you need to start...

Focus on conservation first such as LED power and 12V devices as opposed to inverter...

Tim R. & his wife keep up with use and actually recharge but they have 260W of solar panels and a wind generator.... Their panels for the most part keep up but they also have a very efficient DC fridge system and LED etc...

Maine Sail · Mar 21, 2012

RECESS said:
Do not use an inverter on board.

Still a 15W panel is good for "maintaining" a charge not really for "charging".. A 15W panel at max output is about .85A. Multiply that X about 4.5 hours per day at full output = 3.8 Ah's of charging per day.

A 400Ah bank, pretty common for a boat your size, at 80% state of charge from alternator charging, still leaves you with an 80Ah deficit.

80Ah's X Charge Efficiency Losses @15% = 92Ah / 3.8Ah's Per Day = 24.2 days to go from 80% to full on a 400Ah bank.....

tommays · Mar 21, 2012

I am happy with Mainsails stern mount plan and i used hinged hangers that will allow the panel to fold flat down or up allowing it to take up no lenth in a marina if i am not on a mooring

sailaway78 · Mar 21, 2012

I Agree

With others that a 15 watt panel is hardly worth the effort of installing, and will only at best maintain. If you count on getting any charging from it, you will be dissapointed.

zeehag · Mar 21, 2012

what nne said--i use a display of 4 panels rated at about 3 amps each-- they are good. i have a couple of huge panels i dont need at present-- they are stowed for emergency use. always use a controller.
i found most of the deterioration of solar panels was due to corroding connections.....

rardiH36 · Mar 21, 2012

Just an aside: I've got only a 30w panel. My 110v shore power is never plugged in except when we spend the night and want to watch the DVD and then use the coffee maker the next morning. For this, I haven't yet turned on my 110v smart charger.

Today I was at my boat and while futzing around I listened to my Pioneer 50w x 4 stereo at a moderate/strong level using just my battery "#1". The shore power cord was still in the aft lazerrete locker. Looking at my voltmeter about 20 minutes into the "session", it was registering just over 14V. Two hours later -- 14.2 volts. Conditions today in the San Francisco area were hazy sunshine. Still my 30w panel kept up with the stereo's demand.

Upshot: As Mainsail commented, a small solar panel can't be expected to recharge very quickly a battery that has had any sort of real demand on it. But for a maintainer or for low draw use, I can't complain about my small solar. Great not to disconnect the 30A shore power cord every time we leave our berth.

Bill Roosa · Mar 22, 2012

I'd ditto what others have said, a great maintainer device but you are kidding yourself if you think you are going to use it for any real loads. a single nite at anchor with only the anchor light on is about 3 times what this will collect during the day.
There is a spreadsheet in the downloads section that can help you determine your loads so you can estimate the amount of time you will be needing generator support and size the gas tank.