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Old 07-30-2020, 08:07 PM   #1
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Solar panels on STs?

Looking at a ST 44. I haven't seen anything about anyone putting solar panels on them? Coming from a sailboat, everyone is trying to cram as much solar on as possible!

I don't know if more sailboats are at moorings vs. dock where they are plugged in, but I had 550 W of solar , was on a mooring, and that let me leave my fridge running the whole week while I wasn't there. On sunny days, it also recharged me while I sailed, of course for a ST you are recharging while going so no big deal about the solar for that. But if you are on the hook for 3 days, the only thing you need to run the genny for is the AC. If you don't need AC, you are silent.

So anyone putting solar on their ST or am I barking up the wrong tree?
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Old 07-30-2020, 08:16 PM   #2
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Don't have an ST and didn't even recognize the name/brand.

If you intend to make ANY use of the boat that does not involve an actual run so the alternators can really work then solar can help keep those nice devices such as fridges, coolers, freezers and so on operating without a huge battery bank or killing the batteries.

Often trolling operation may not run the alternators hard enough to take care of the draw from all the gear.

Even the electronics will benefit with a more consistent voltage supply.

Just my thoughts.
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Old 07-30-2020, 08:21 PM   #3
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Don't have an STR and didn't even recognize the name/brand.
.
Posting in Swift Trawler, ST , forum so figured people would know ST...

Many thanks for that quick reply. Appreciate it.
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Old 07-30-2020, 08:32 PM   #4
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There are several recent posts on solar which may address your questions. Suggest you search the archives.
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Old 07-30-2020, 08:57 PM   #5
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A few thoughts:
1. Some have installed on top of their bimini. personally, i like folding my bimini back, so no go for me.
2. solar requires optimal conditions to hit max. my power usage wont work with solar. so i expanded my battery bank to nearly 1,000 aH and got a larger charger that can re-charge me in a a few hours of the generator running.
3. i was actually thinking at one point a wind generator might work, mounted up on the fly bridge, aft. have yet to see anyone do that though...
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Old 07-30-2020, 10:28 PM   #6
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There are several recent posts on solar which may address your questions. Suggest you search the archives.
Thanks, but specifically looking for solar on ST ,not in general. Didn't see any threads in this forum on it.
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Old 07-30-2020, 10:30 PM   #7
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A few thoughts:
1. Some have installed on top of their bimini. personally, i like folding my bimini back, so no go for me.
2. solar requires optimal conditions to hit max. my power usage wont work with solar. so i expanded my battery bank to nearly 1,000 aH and got a larger charger that can re-charge me in a a few hours of the generator running.
3. i was actually thinking at one point a wind generator might work, mounted up on the fly bridge, aft. have yet to see anyone do that though...
Thanks.

What are the sizes of your alternators. I would think these could put out much more power than a Genny even with say a 100A charger.
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Old 07-30-2020, 10:33 PM   #8
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Thanks.

What are the sizes of your alternators. I would think these could put out much more power than a Genny even with say a 100A charger.
I think my alternators are 100a each or thereabouts

Problem is we stay at anchor for weeks at a time some time

They do a good job keeping things charged up when we are hopping from place-to-place

I would not run my engines just to charge things, only if going somewhere
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Old 07-30-2020, 11:29 PM   #9
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The major issue with your boat if it conforms to the video posted below in terms of solar is - where do you put the panels? Fly bridges eat room and you do have room on the hard bimini but then you lose deck space above.

This is a problem for many trawlers and boats with fly bridges, little space for solar panels. It looks like you might get a few panels in the bow deck area, but hard to tell.

I don't have a trawler or B ST but with my sedan cruiser, I have room on top of the saloon for three solar panels. I married those panels with an 210 Efoy unit and the combo allows me to go weeks if I want on the hook. But I don't have any big ticket items requiring AC. The stove/oven is propane, I have one dedicated fridge and a separate dedicated freezer and I will run a small appliance or two for ten to twenty minutes in a day. I have 6 firefly batteries as my house bank.

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Old 07-31-2020, 12:46 AM   #10
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How about hanging them on the railing around the deck to the rear of the flybridge? Some people here have done that and swing them up and down according to being used or not. You can search the archives for the threads, but it will work on any boat that has rails up there not just STs.
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Old 07-31-2020, 12:56 AM   #11
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How about hanging them on the railing around the deck to the rear of the flybridge? Some people here have done that and swing them up and down according to being used or not. You can search the archives for the threads
Member FlyWright recently showed some photos of that concept (was lower rails but could apply to upper).
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Old 07-31-2020, 07:20 AM   #12
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The major issue with your boat if it conforms to the video posted below in terms of solar is - where do you put the panels?
people reinforce the bimini and put them on top of the bimini
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Old 07-31-2020, 10:34 AM   #13
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I would first get a handle on your DC requirements, how much time you spend at anchor, how long you run to get to the next anchorage, etc before jumping into solar.

With your hull configuration you are limited in where you can put solar panels. The aft boat deck will be shaded by the bimini in some wind directions. The foredeck will get trampled underfoot while raising/lowering the anchor. The bimini is the best place for solar panels, but without reinforcing the bimini frame you are probably limited to flexible solar panels which are about 1/3 the weight of aluminum frame panels.

I am not a big fan of them- they are expensive, sometimes don't put out their rated power, and older ones at least deteriorate quickly electrically. But they have their place and are fairly easy to install on top of the bimini canvas- just stich the corners to the bimini fabric.

But other solutions come to mind. The OEM alternator on your engines- twin Cummins, right?, have a fixed voltage internal regulator that doesn't charge batteries very fast. Replacing one or both alternators with a high output like a Balmar alternator with an external regulator will vastly increase charging amperage. You will go from maybe 20A per alternator to 100A.

With a big enough battery bank and moving every 2-3 days you may get by with the propulsion engine alternator recharging your battery bank if you upgrade to high output. It all depends on how you use the boat.

I would first install a battery monitor like the Victron or Renogy and see what your power usage profile is.

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Old 07-31-2020, 10:54 AM   #14
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I would first get a handle on your DC requirements, how much time you spend at anchor, how long you run to get to the next anchorage, etc before jumping into solar.

With your hull configuration you are limited in where you can put solar panels. The aft boat deck will be shaded by the bimini in some wind directions. The foredeck will get trampled underfoot while raising/lowering the anchor. The bimini is the best place for solar panels, but without reinforcing the bimini frame you are probably limited to flexible solar panels which are about 1/3 the weight of aluminum frame panels.

I am not a big fan of them- they are expensive, sometimes don't put out their rated power, and older ones at least deteriorate quickly electrically. But they have their place and are fairly easy to install on top of the bimini canvas- just stich the corners to the bimini fabric.

But other solutions come to mind. The OEM alternator on your engines- twin Cummins, right?, have a fixed voltage internal regulator that doesn't charge batteries very fast. Replacing one or both alternators with a high output like a Balmar alternator with an external regulator will vastly increase charging amperage. You will go from maybe 20A per alternator to 100A.

With a big enough battery bank and moving every 2-3 days you may get by with the propulsion engine alternator recharging your battery bank if you upgrade to high output. It all depends on how you use the boat.

I would first install a battery monitor like the Victron or Renogy and see what your power usage profile is.

David
I am going to try to remember to use my amp meter to see what they are outputting next time! I am actually curious but seem to be able to re-charge 3-400 amps in a few hours. So I dont think 200 amps is going into the house bank but maybe 80-100 amps. Using the OEM volvo alternators.
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Old 07-31-2020, 12:49 PM   #15
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I am going to try to remember to use my amp meter to see what they are outputting next time! I am actually curious but seem to be able to re-charge 3-400 amps in a few hours. So I dont think 200 amps is going into the house bank but maybe 80-100 amps. Using the OEM volvo alternators.
Wow and wow!! (double wows!!). 200 amps from two stock alternators.

I have one data point with a single Yanmar 370 hp engine with a stock Hitachi 80 amp alternator on a recent boat. When the 4 GC batteries were 20% discharged the alternator would supply 20 or so amps. If they were 50% discharged the alternator would put out 50 amps for the first hour or so then slowly taper back to 20 amps as they recharged.

OEM alternators have a fixed voltage output of 13.5-14.0 volts that limits charging amperage particularly as the batteries get above 75% charged. You need to go above 14 volts to charge fast at that level of charge which is what external regulators do.

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Old 07-31-2020, 01:19 PM   #16
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A lazy way to check your alternators for power output is to check the fuses, willing to bet you find the fuse significantly less than 100 amp.

Many up here in the PNW & coastal BC just try to get a few more days on the hook. So with my set up with 6 fireflies, I have approximately 560 usable amps. Lets assume I'm using 250 amps daily and I remove my Efoy. And I don't use my engine.

My solar will generate roughly 75 amps a day, so if I am on the hook for three days, 225 amps are put back in the system. Which gives me a total of 560 plus 75 amps at 250 amps a day, allows me 3 days on the hook before I need to either use my engine or head to a marina. My engine alone would not generate enough amps to replace 560 amps (really 500 amps, I didn't use the other 60)

So solar up here on the Wet Coast is used to buy more time on the hook, but there still remains a need to go to marinas, just not as much. So on a 28 day trip (nice round number to keep the math simple) you would be at marinas for 7. So do that enough times and you have paid for the solar system.
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Old 07-31-2020, 01:26 PM   #17
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Wow and wow!! (double wows!!). 200 amps from two stock alternators.

I have one data point with a single Yanmar 370 hp engine with a stock Hitachi 80 amp alternator on a recent boat. When the 4 GC batteries were 20% discharged the alternator would supply 20 or so amps. If they were 50% discharged the alternator would put out 50 amps for the first hour or so then slowly taper back to 20 amps as they recharged.

OEM alternators have a fixed voltage output of 13.5-14.0 volts that limits charging amperage particularly as the batteries get above 75% charged. You need to go above 14 volts to charge fast at that level of charge which is what external regulators do.

David
I think you are correct. Once the batteries get to a higher SoC the charging speed does slow down.
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Old 07-31-2020, 01:27 PM   #18
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So your expensive strategy may go something like this. Replace your FLA batteries if that is what you have with more efficient energy dense batteries, like Fireflies or Lithium. If you have room add more batteries.



Then try to add as many panels as possible without destroying your boats looks cosmetically.

You could add Efoy to supplement your solar.
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Old 07-31-2020, 02:21 PM   #19
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What Li gets you is the ability to take in A as fast as whatever can output them regardless of SOC.

I am stunned to hear that 2 300HP engines only have stock Hitachi 100A alt. I had 2 30HP yanmars on my sailing cat, and that had stock 80A alt! Is this true, that the ST 44 only has stock 100A Hitachi alternators?

If I pull the trigger on a ST44, then for sure I would look at upgrading to a smart alt system, and possibly Li/Firefly etc.

RSN, you are exactly correct. I had 450Ah and used about 150Ah a day. I had 550W of solar and on sunny summer days, I could easily get 150Ah, so I could sit on the hook forever without going in to charge. BTW, 1:1 ratio for Ah of battery and W of solar seems to be a good ratio. If I ran both engines for 1 hour and the battery was in bulk mode, I could get about 100A in from the 2 80A, which if I was at 50% SOC, would get me to about 75%. Another hour would put in only 50A since I was sort of exiting bulk mode and the alts would be too hot.

Hence the reason I asked about solar on the ST 44. I could see at least putting up flex solar panels on the top of the bimini, you could probably get at least 200W up there and that would probably keep the fridge charged up while on hook.
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Old 07-31-2020, 06:49 PM   #20
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Google "Will Prowse," he's a young guy who is self taught but is becoming well known in the RV world for his solar work, research, etc. You will also find some recommendations of panels that work well but are cheaper.

Will Prowse doesn't like flexible panels, they definitely have a shelf life unlike the solid ones. And even in the first year you can loose 10% of performance. I will snoop and try and find one of his videos:

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