Solar charging options

walt

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
I've heard that a good rule of thumb is to estimate that you'll get ~5 hours per day of your panel's maximum power, spread over ~12 daylight hours. So a 50w panel might deliver ~250 watt-hours. In reality, it will be much less than 50w in the morning and evening, and only come close to peak output (if you're lucky) around mid-day. Here in the cloudy PNW, I estimate 3.5 hours.
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FYI, technical details here.. but I didnt want to disagree with AaronD as the above is also a good way to estimate solar output. Its a fair way I think. I wanted to compare it to the .2 to .5 times rated power rule of thumb that I actually got from this forum years ago.

Amp hours is not an actual energy capacity term. To be technically accurate, this should be watt hours (like AaronD and your home utility company use). But 12 volt boat folks like to use amp hours for capacity with the assumption that its a 12 volt system. Why.. Im not sure but I will guess battery charging is not completely efficient and you lose a little. Ie, watt hours in to the battery from the charge source is greater than watt hours out to the load. However, since battery charging generally occurs at a higher voltage (example 13.5 volts) than battery driving a load (example 12.3 volts), using amp hours "kind of" takes into account the loss so that amp hours in is closer to amp hour out compared to using watt hours. Ie, using amp hours somewhat automatically takes into account the battery charging inefficiency. Regardless, you will almost always see amp hours used with the assumption that its a 12 volt system.

So.. for the 50 watt panel producing 250 watt hours per day, lets say this happens at an average voltage of 13 volts. So the equivalent amp hours would be 250/13 = 19.2 amp hours.

So for the rule of thumb I used, 50 watt peak power / 19.2 amp hours = .38

Remember I had a range of .2 to .5. So .38 is in this range. I measured this one time under a particular set of conditions (using a battery monitor and a Genasun MPPT controller) and got .33 for that particular day/ location. So many things cause the solar output to vary (temperature, time of year, clouds, panel pointing, any even small shading, insolation for a particular location. MPPT or PWM).

Anyhow .. didnt want to conflict with what AaronD said as its correct.
 
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Rltgold

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Mar 2, 2018
232
Catalina Wing Keel San Diego
Hi Everyone and thanks for all the help. I just got back for a month long trip to Magdalena Bay and the Loreto area. My electrical/battery/solar system worked good but with a lot of cloudy days it was slim on keeping the battery up to full power.
I am going to add to my panel I have and so far in trying to learn the math to do so I thought I'd share with you what I have learned as of today.
Bottom line my 13W goal zero panel is not enough !
So here is my list of what I use and the total AMP hours /Ah and Watt hours /Wh
This is based on 24hrs
Cabin lights LED 2Ah (We use Led solar Luci lights and headlamps most of the time)
VHF Radio 3Ah
Compass light / Depth sounder 2
Autopilot 5.6
Anchor light 5
Total 18 AH / 216 Wh 18Ah x 12V battery = 216 Wh

These Ah are broken down into day and night usage but the total ends up being 18Ah

We found a website that uses a calculation of 5.5 x Panel rating in watts to figure out your Wh.
With my dinky 13w panel it's,
5.5 x 13W = 71.5 Wh A far cry from the 18AH/ 216Wh I am using. No wonder I'm always feeling short.

So with this information we (My wife has been very patient with me trying to help along with the people at Goalzero)
WE have figured out that this is the minimum I need to be able to use my complete system and keep it charged.

18Ah / 216Wh divided by 5.5 = 39.27 W panel
I can ether add a 28w panel to the 13w panel for a total of 41w or buy 2 28w panels and have 56w total.
I am at the moment leaning on adding the 28w panel to the 13 w panel. They plug (chain together). I already have the controller.
I liked how other people have their panels mounted on their boats but I like being able to pull the soft panels out as soon as the sun comes out and clip them to the cabin top and the right angle for charging.

I hope I'm making any sense at all and am helpful.

Thanks again to everyone.
 
L

little breeze

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Jan 23, 2015
92
catalina catalina22 Trailer
Minnesail said:
I think the controller you use is at least as important as the solar panels.

I use a 50-watt panel and a Genasun charge controller. I spent more on the controller than on the panel.

I use an electric trolling motor instead of a gas outboard, so I'm reliant on electricity.

The 50-watt panel is more than enough when I'm day sailing three times a week.

It doesn't keep up when I'm camping out on the boat. Between playing music, charging phones, and running the lights at night I'm using just a little more than what the panel puts out. But I only stay on the boat for two days, so I have plenty of reserve battery, and after a couple days away from the boat the battery is back to full again.

If you want to be out for a week and plan on using a moderate amount of electricity you might want a 100-watt panel.
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R

Rltgold

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Mar 2, 2018
232
Catalina Wing Keel San Diego
Hi Everyone thanks so much for all the help!.
My system on Minnie is very simple
Cabin Lights (Led's)
VHF Radio pre charged (Also a handheld w/2 extra pre charged batteries)
Compass light/depth sounder
Auto pilot
Anchor lights

I don't run much at night so I don't list those .

My total Ah based on 24 hours is 18Ah which I think is high but it's a good place to start.
I have been able to go out for 10 days so far without loosing power but I tried to stay in known anchorages where you don't have to have an anchor light. I do hang a bunched up string of LED christmas lights up on the spreaders.
Have a 12v AGM battery of unknown age. Fully charged it reads 13.25
I have been charging it before hand with dock power. Then while underway with a goal zero 13w panel using their controller. I calculated (I hope this is right) that I need 39w coming in to keep the battery fully charged so I am adding a 28w panel in line for a total of 41w.

18Ah x 12V =216Whs divided by 5.5 = 39.27 W

I like the way Gene has his panels mounted. I sent him a PM asking if he bought the mounts or made them and have't heard back. I am not sure I want to install panels like that. At this point I just pull out the folding panels and clip them on to the top of the cabinet at the best angle possible
 
AaronD

AaronD

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Aug 10, 2014
723
Catalina 22 9874 Newberg, OR / Olympia, WA
R

Rltgold

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Mar 2, 2018
232
Catalina Wing Keel San Diego
Thanks Aaron,
Unfortunately I am boycotting anything from Seadog due to my experience with them regarding their worthless deck plug connectors. They couldn't care less if they a badly designed and never bothered to answer any emails or phone calls
 
Zinger88

Zinger88

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Sep 25, 2019
59
2002 Cat 22 MkII Lake Somerville
Lazy1

Lazy1

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Aug 23, 2019
173
Catalina 22 13425 A driveway in Pittsburgh
rpludwig

rpludwig

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May 23, 2016
1,024
Catalina 22 #12502 BSC
like it, the mount and panel size, nicely done! only question, does that not interfere with your outboard access (head banger) in that location?, or do you flip it outboard, hanging over the motor, beyond the transom and thus above the outboard?
 
Zinger88

Zinger88

.
Sep 25, 2019
59
2002 Cat 22 MkII Lake Somerville
rpludwig said:
like it, the mount and panel size, nicely done! only question, does that not interfere with your outboard access (head banger) in that location?, or do you flip it outboard, hanging over the motor, beyond the transom and thus above the outboard?
Click to expand
I was concerned about that as well but haven't experienced any issues with access to the outboard. Sure its not as clean an access as before, but after a few adjustments to my routine I hardly notice the panel in the way.
 
Gene Neill

Gene Neill

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Sep 30, 2013
3,541
1988 Catalina 22 North Florida
With that MkII pushpit, it's not like you had any alternative. Well done. :thumbup:
 
Zinger88

Zinger88

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Sep 25, 2019
59
2002 Cat 22 MkII Lake Somerville
Thought I'd include the rest of my setup as FYI for those researching options for solar installs:

I decided to go with a Renogy 30W panel which came with 4' leads and bare wire ends.

61PZ2xVn8GL._AC_SL1000_.jpg
Renogy 30 Watt 12 Volt Monocrystalline Solar Panel

Also purchased a Victron SmartSolar MPPT 75/10 Charge Controller with Bluetooth which I mounted next to my switch panel located behind my cooler step. This gives me easy visual viewing of the controller in addition to utilizing the bluetooth Victron app on my iPhone (which is awesome!).


71VIA5EmQLL._AC_SL1200_.jpg Victron Controller_1.jpg Victron Controller_2.jpg Victron Controller_3.jpg
Victron SmartSolar MPPT 75/10 Solar Charge Controller w/ Bluetooth

I went with a 16ft 14AWG extension cable with SAE/SAE 2-pin quick disconnect wire harness to run from the solar panel to the controller. I cut off the wire harness connector from one end of the extension cable and reused it on the bare ends of the solar panel leads using heat shrink butt connectors.

71DdkxmzZqL._AC_SL1500_.jpg
SAE/SAE 2-pin Quick Disconnect Wire Harness

The newly cut off bare wire end of the extension cable was then run thru the deck to the controller using a Scanstrut Horizontal Deck Seal.

Scanstrut 2.jpg Scanstrut 1.jpg
Scanstrut Horizontal Deck Seal

I don't have any photos of the wire connection from controller to the battery, however I utilized 14AWG wire with ring connectors for that. Thus far my setup is working perfectly in keeping my Group 24DC battery topped off.

Interstate 24DC.jpg
Interstate Batteries Deep Cycle 24DC Marine Battery

Hope this helps for those out there contemplating a solar setup. One thing I learned in my research on this forum is that there's a gazilion different ways to cook this egg. I went with a combination of ideas found here until I whittled it down to what worked for me. Thanks to all those before me who posted their solar setups and ideas on the forum. Our Cat 22 community has a wealth of knowledge and information!

Zinger88
~~ _/) ~
 
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Zinger88

Zinger88

.
Sep 25, 2019
59
2002 Cat 22 MkII Lake Somerville
rpludwig said:
like it, the mount and panel size, nicely done! only question, does that not interfere with your outboard access (head banger) in that location?, or do you flip it outboard, hanging over the motor, beyond the transom and thus above the outboard?
Click to expand
Zinger88 said:
I was concerned about that as well but haven't experienced any issues with access to the outboard. Sure its not as clean an access as before, but after a few adjustments to my routine I hardly notice the panel in the way.
Click to expand
Welp...after a period of time dealing with obstructed access to the outboard due to solar panel location, I realized it was becoming too much of a pain in the a**. :mad:

So after considering options, I decided to relocate the panel to the other side even though the swim ladder is there. Our use of the swim ladder will be rare based on how/where we sail, and if needed, we can always unplug and remove the solar panel should the need arise.

IMG_3744.JPGIMG_3745.JPG



And plus...the less time I have to deal with messing around with access to the outboard...the more time I have to enjoy an evening sail like this! :waycool:

IMG_3742.JPG
 
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Gene Neill

Gene Neill

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Sep 30, 2013
3,541
1988 Catalina 22 North Florida
Good move. (Sorry, the pun was unavoidable.)

No matter who you are, you're gonna need to access the motor more often than the swim ladder. And sometimes, with MUCH greater urgency.
 
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