Solar charging

[Durant F]

I was asked about my solar on another thread and thought starting a new one dedicated to solar would be best.
I’ve done solar for over 10yrs now both at an off grid cottage and on multiple boats.

First off..
-you need an “energy Budjet” meaning “how much do you use?”
Lights LED?
Fridge efficiency?
Freezer?
What other 12v draws do you have?
Charging laptop? Cell?
On and on...
Realize that anything...anything that creates heat is a no no with solar!
Try to figure how many amp hours you will use on a typical day

Then

You don’t want to run your batteries low...
They will cycle to 60% multiple times
Draw them down to 40% and your cutting lifespan significantly
If you need 100amp hours per day... you should have 300amp hours of batteries

Then, based on that, panel size... (and how much average daily sun?)
If you need 100amp hours charged and say, 6 hours of sun... you need a big panel capable of 15+ amps

So much depends on you..and how you set your boat up and use it.

There is no definitive answer... all depends on your situation

Here is what, from past and current experience I know works for me

- one large panel is simpler/better than multiples

-it must...MUST be adjustable so you can angle it for maximum exposure. A small adjustable panel with out perform a much larger fixed panel! Seriously!!
Mount it high and away from things that will shade it if possible.

-an MPPT controller is a must as well. So much more efficient!

-set your boat up for lower draw ei: LED everything, charge things while underway, even things as simply as shutting off your propane solenoid saves power! mount your panel for maximum exposure and adjustablility.


I do not expect to be solely on solar out here in the PNE. The sun is so unpredictable.
My southern sailboat is pure solar and I can be ON the hook for weeks.
My solar here is a fully adjustable 165 watt panel with an MPPT controller.
See tonight’s picture.
Tipped forward
Making 6.6 amps later in the day (8+ earlier)
Batteries at 13.6
I’ve also attached a picture of the panel tipped backwards.
To me, this adjustability is critical!
I’ve seen the panel making 1.8, then tipped it towards the sun and it will exceed 6 or more.
While I can’t “just” have solar out here in the fall season, I’ll have no need to start my generator tonight or in the morning before I leave. That said, if tomorrow was cloudy, by noon I’d be starting it.

I sailed a boat for 5 seasons, never plugged in, all LED and ran a “fridge only” with a 215watt panel and 4-105 amp hour gulf cart batteries
Beige boat picture

I sailed a much larger boat, never plugged in, fridge and nice size built in freezer, all LED with a 255 watt panel and 4-230 amp hour batteries
White boat pictures

Notice the panels tipped on all the pictures

Hope this helps

 

[rsn48]

it must...MUST be adjustable so you can angle it for maximum exposure. A small adjustable panel with out perform a much larger fixed panel! Mountbit high and away from things that will shade it if possible.

Fixed panel can be better than a solar panel that adjusts, it really depends where the fixed panel is. Although for docking purposes I would love to have a flybridge, for everything else, I'd rather have an express or sedan cruise styled boat as you have so much room above to lay panels flat. These flat panels laid roughly parallel to the water get far more sun than an adjustable one. Boats make to many course corrections (especially a sailboat) both underway, and moving around at anchor. A fixed panel laid flat, in my case 3 panels laid flat are much more efficient than adjustable panels.

 

[Durant F]

When “flat” makes more sense, mine are adjusted “flat”
See picture...
Early morning sun or later afternoon on... adjusted to the sun really increases the amperage.
We all have our own opinions based on our own experiences
Glad yours work better fixed flat for you.

 

[rsn48]

Curious, I see you live in Pembroke but which one?

 

[Durant F]

Pembroke Ontario
-30, 4ft of snow Pembroke
Built homes for a living and back in 2002 had enough wrinkles and grey hair to realize it costs too much to build in winter so took my sailboat south.
Retired now, still cruise the Abacos in winter, PNW in fall and home in summer.
With Covid, staying out here this winter.

 

[Al]

Thanks Durant,

Seeing the location on the trawler clears the location factor for myself as I have the same railing installation. As to all of the offered technical information, Wow!! Lots to it, which exceeds my "Struggled to graduate high school" mentality. Thanks for the data, you have convinced me to employ the local 'Wizard of Electrical Smarts' to determine panel size to power the given data on the selected freezer.

Al-Ketchikan

 

[Durant F]

Al...
At least you struggled and made it..
I have grade 10,??

Frank

 

[IRENE]

Thanks for posting this thread, Frank. We are having discussions about adding solar, but I suppose we are allowing the technology to advance as we won’t be cruising full time for 2 years.

What are your thoughts about some flexible (lightweight) Sunpower panels that we can deploy on the bow when on the hook, yet store away while on passage or on the grid? They would be “adjustable” for angle to the sun as we have bulwarks, lifelines, and rails that will allow them to be angled as desired.

Thanks

 

[Curiosity]

Great information from someone using solar.

I am wanting to set up our 32 ft Nordic tug with solar on pilot house roof. There is a 9 ft x 10 ft area up there fairly flat. Had assumed I would just bolt down as many panels as would fill space and not adjust them. Sounds like tweeking them during the day could realistically cut down on the amount of panels. Had wondered about also having a wind generator combined with the solar. Just starting to look at what kind of load we use, all lights are old school not sure how hard they are to switch out. Had thought I would also use the golf cart batteries.
Will watch post for more info. Never been around solar, starting to wrap my mind around it. A lot of conversions and decisions on components.

 

[rsn48]

Pembroke Ontario
-30, 4ft of snow Pembroke
Built homes for a living and back in 2002 had enough wrinkles and grey hair to realize it costs too much to build in winter so took my sailboat south.
Retired now, still cruise the Abacos in winter, PNW in fall and home in summer.
With Covid, staying out here this winter.

I thought so. At one time, my dad was the second in Command of CFB Petawawa in fact during the FLQ crises. The troops that were deployed to Ottawa during the crisis were deployed by my Dad. The general - Wradley Walthers - CO of the base had gone on vacation to Florida leaving the 2OC in charge. When the crisis blew up, pre smart phones, internet, etc, he couldn't be reached so my dad was in charge of troop deployment in Ottawa. All the troops, with the exception of the Reserves were Petawawa based.

Every base has a "servicing town." So Barrie is Borden's town and Pembroke is Petawawa's town. I was into Pembroke every weekend with my parents for sometime. Nice Ontario town.

 

[Durant F]

Too funny!
Home is between Pembroke and Petawawa.
I worked far more in Petawawa than anywhere and early on worked on base.
His son, Grant Radley-Walters was my lawyer for 28yrs before becoming a judge. Retired now as well... a good friend to this day. Small world...

Curiosity... I had a 2006 Nordic Tug 32/34 for my first few years out here. Great boat. Converted to 4-6volt golf cart batteries for house and a 200 watt panel.
Sure cut down on running the Honda 2000. If sunny...all good. Like politics, religion and anchors... I’m sure there will be lots of opinions on solar. My thoughts are if less panels will do the job then it’s simpler and the MPPT controller doesn’t have to be as big-expensive either. This is year 15 with solar on my boats and I truly do believe in adjustability. Solar has limits and you really have to work with it ei: LED bulbs and charge items underway running engine etc. Once onto it, you’ll be glad you did.

Irene... I used flex panels on my boat back in 2007. Wasn’t totally happy but flex panels have come a long way since then. Issues are storage and cost. Very expensive compared to fixed panels. Again...they’ve come a long way and far less than back then...

 

[BruceK]

As to adjustable angle of attack/exposure of panels, I cannot see people constantly adjusting during the day. As the boat rotates or swings on anchor or mooring,optimal positioning keeps changing. There are large land based solar farms where panels adjust to changing sun positioning, either automatically or manually, but it`s hard to see that working in practice on a boat,unless it`s in a slip. Seems easier to accept that fixed panels will, at times, be sub-optimally positioned.

 

[Durant F]

Bruce, Actually, you don’t constantly change the angle of the panel.
Most of the day flat is fine. Where the benefit comes in is early and late sun when it isnt high above. Typically at anchor you would tilt it towards sun up, flat the majority of the day and tipped down towards sunset. At Conover Coves dock yesterday, tipping it up made a 4+ amp charging difference for the last 3 hours of sunlight. There is no electricity available at those docks. That extra 12+ amp hours will run my fridge and LED reading lights for about 3 hours longer than had I not tipped it.
While it’s true you can swing at anchor, generally it’s only the early and later low sun you’re trying to get the most from.
The picture attached is one of my favourite sunset shots! Quite beautiful, taken at MANJACK Cay in the Abacos. Of note, the panel is still making power probably 3+ hours longer than it would have had it been flat
Folks can certainly choose several larger panels and a much more expensive MPPT controller to capitalize on the reduced optimum charging time. Some do it that way intentionally, others because they’re unaware of the increased efficiencies of adjusting panel angle. There really is no right or wrong way. I’m more frugal and a bit of a minimalist by nature so prefer the smaller adjustable panel.
What size panels do you use?

 

[Simi 60]

We have ours mounted flat, no way in hell am I getting up on the roof to try and adjust 9 panels.

Any inefficiency or loss is made up for with extra panels
Panels are cheap, adjustable mounting brackets are not.

 

[Durant F]

You sir, are running a small ship
Just having enough real estate to put 9 panels down is out of my tax bracket ?
I’m just trying to keep my fridge/freezer going without starting the generator..

 

[rslifkin]

Tilting makes sense to me if you're limited on space for panels and the space you have is conducive to a tilting mount. But it's just not practical on a lot of boats unfortunately.

 

[Curiosity]

Solar

As I pursue the solar idea.
Does anyone have a solar worksheet they like to use? Is it better to try to buy a system in a kit or buy the pieces and put it together.

 

[RT Firefly]

Greetings,
Messrs. DF & rs. Good grief. Old home week. We used to canoe the Barron River every fall to leaf peep. Yep, left from Achray and took out 2 or 3 days later along the system.


Also used to drive into Cedar Lake for the spring pickerel opener. In from Deux Rivierres to Brent. Best time to drive the 25 mile "road" was 4 hours.

 

[Group9]

it must...MUST be adjustable so you can angle it for maximum exposure. A small adjustable panel with out perform a much larger fixed panel! Mountbit high and away from things that will shade it if possible.

Fixed panel can be better than a solar panel that adjusts, it really depends where the fixed panel is. Although for docking purposes I would love to have a flybridge, for everything else, I'd rather have an express or sedan cruise styled boat as you have so much room above to lay panels flat. These flat panels laid roughly parallel to the water get far more sun than an adjustable one. Boats make to many course corrections (especially a sailboat) both underway, and moving around at anchor. A fixed panel laid flat, in my case 3 panels laid flat are much more efficient than adjustable panels.

The problem is, almost everyone we saw while cruising, who had adjustable solar panels, had become tired of constantly adjusting them and just put them in the optimum position and left them there.

 

[rsn48]

Out here in lotus land during our "winter" days, heavy cloud cover often rain, the potential of the sun, much further south on the horizon, to provide solar power is almost non-existent. I added an Efoy 210 to the boat. This methanol fuel cell has approximately 950 amps per cannister of ethanol, 10 litres.

I also have 6 firefly batteries for a total of 700 amps of which 560 is available before I need to charge them. And of course the motor alternator charges the batter house bank when underway. So the fuel cell is usually just topping up, I run about 150 amps per day. I can be out for a couple of weeks before I change out the fuel cell cannister - in the winter.

 

[FF]

"I’m just trying to keep my fridge/freezer going without starting the generator.."

On some boats there is space to glue extra insulation to the exterior of the reefer.

Plastic bottles of salt water frozen in the freezer compartment may help by allowing the unit to be shut off overnight.

 

[rslifkin]

"I’m just trying to keep my fridge/freezer going without starting the generator.."

On some boats there is space to glue extra insulation to the exterior of the reefer.

Plastic bottles of salt water frozen in the freezer compartment may help by allowing the unit to be shut off overnight.

I'll second the additional insulation. More insulation is a big improvement to just about any boat fridge. Unless it's a custom built box, none of them have as much insulation as they really should.

 

[jgwinks]

Great information from someone using solar.

I am wanting to set up our 32 ft Nordic tug with solar on pilot house roof. There is a 9 ft x 10 ft area up there fairly flat. Had assumed I would just bolt down as many panels as would fill space and not adjust them. Sounds like tweeking them during the day could realistically cut down on the amount of panels. Had wondered about also having a wind generator combined with the solar. Just starting to look at what kind of load we use, all lights are old school not sure how hard they are to switch out. Had thought I would also use the golf cart batteries.
Will watch post for more info. Never been around solar, starting to wrap my mind around it. A lot of conversions and decisions on components.

You can get LED bulbs for darn near any light fixtures, so no need to change them just to get LED's. Which ever way you go be aware that incandescent bulbs don't care about polarity but most LED's do. If an LED bulb doesn't work when you first plug it in, you'll have to reverse the polarity. If it's a festoon bulb, those are the ones with contacts on either end, just turn it around. If it has a socket you'll have to drop the fixture and reverse the wires. Some people doing this found the the lights were wired with all the same color wire so you couldn't even tell which was positive or negative. With the original bulbs it just didn't matter.

 

[jgwinks]

I'll second the additional insulation. More insulation is a big improvement to just about any boat fridge. Unless it's a custom built box, none of them have as much insulation as they really should.

But don't insulate the back,that's where the heat removed from the box is dissipated. Insulate that and the refer won't work at all. Really old refers had a visible grid on the back that was pretty obvious. On newer one's the grid is inside to keep it clean and the metal skin acts a a heat sink. Adding insulation to the bottom would be the most effective but harder to do.

 

[jgwinks]

We have ours mounted flat, no way in hell am I getting up on the roof to try and adjust 9 panels.

Any inefficiency or loss is made up for with extra panels
Panels are cheap, adjustable mounting brackets are not.

And if the wind or current changes, the panels will be pointing completely the wrong direction. Mine stay flat.

 

[rslifkin]

But don't insulate the back,that's where the heat removed from the box is dissipated. Insulate that and the refer won't work at all. Really old refers had a visible grid on the back that was pretty obvious. On newer one's the grid is inside to keep it clean and the metal skin acts a a heat sink. Adding insulation to the bottom would be the most effective but harder to do.

Depends on the fridge. Most marine fridges still have the condenser outside the box and visible, not hidden like modern home fridges. Mine has the condenser, fans, compressor, etc. all underneath, nothing on the back, which makes it easy to add insulation.

 

[stubones99]

Great information from someone using solar.

I am wanting to set up our 32 ft Nordic tug with solar on pilot house roof. There is a 9 ft x 10 ft area up there fairly flat. Had assumed I would just bolt down as many panels as would fill space and not adjust them. Sounds like tweeking them during the day could realistically cut down on the amount of panels. Had wondered about also having a wind generator combined with the solar. Just starting to look at what kind of load we use, all lights are old school not sure how hard they are to switch out. Had thought I would also use the golf cart batteries.

Rather than mount them to the roof with clips, lay down a sheet of polycarbonate (hurricane window panel), with the panels mounted to the sheet, then you have fewer holes in your roof, and the panels have a way of staying cooler since the corrugated holes in the storm panel leave room for an air gap since solar panels heat up in sun, and higher temperatures make their output drop off.

Mount the polycarbonate sheet to your roof on the corners with a single junction box where all the panel wiring goes into the box for dry connections.

https://www.lowes.com/pd/Storm-Busters-48-in-x-96-in-Clear-Polycarbonate-Hurricane-Shutters/3041437

 

[Jeff F]

I mounted flexible panels on the roof of my PH using 3M VHB tape in parallel strips. No holes except for cabling, and a bit of air between the panels and the deck for cooling. Very happy with the results.

 

[tmw]

I have one comment on sizing an array and batteries. When I ran my calculations I came up with a max of 90 amp hours per day. This was actually read off a battery meter for an entire season before we had solar. So I knew it would be pretty accurate for a 24 hour period. We had one pair of 6v golf cart batteries at 200+ AH and it was plenty under most circumstances if we conserved power.


What I didn't think about was that, with solar, we actually only need batteries at night or roughly half the amp hours. During sunny days, I'm charging and running off the solar for a good part of the day. My array is 2, 165w, flex panels, in parallel, laying flat on the hard top. By 8am, in the Northeast US, I'm producing enough power to run my fridge and start putting a charge back in the batteries. At that point, I figure, I'm no longer using battery power at all and running entirely off the sun. By 1 or 2 pm, the MPPT charger starts to kick back to trickle charge. So my overnight battery requirements are more like 45 amp hours. Well under the capacity of the battery and that's mostly from refrigeration and some lighting.



So it turns out I'm somewhat oversized for a 36 ft boat. Maybe I could have gone with 100 watt panels but it helps on cloudy days to have the larger array. So my advice is to not go too overboard on either your panel requirements or battery sizing. Oversize to help on cloudy days but don't get too carried away.


BTW, even right now, under the white shrink wrap, the panels produce 2+ amps, mid day. So solar has come a long way.





Good luck

 

[FreeSpiritSue]

Hi Durant, this is my 2nd boat that I’ve switched to total solar. I have 2 165watt solar panels on my Cuddles cabin cruiser 30’. An MPPT & a Fangpusen battery monitor. I’m very lucky to live in sunny QUeensland, Australia. Several months ago I bought a USA made Heliatos solar hot water panel & a 10 liter tank. It takes 20minutes to heat to 50 degrees Celsius. It’s important as you would know to switch it off on the panel after use. I haven’t used it a whole lot over summer but I’m very happy with it.