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Floridian setting up motor yacht with enough solar to power the AC at anchor!

1981Seafarer

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May 31, 2021
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Hello from the Sunshine State! What do you get when you open the furnace door and toss in a tub of boiling water? A Floridian summer!

As such, my recently-purchased 40' motoryacht just sits in it's slip, plugged into power to keep the AC going.

The generator is shot, and I don't really want another complex device consuming fuel anyhow (the two main engines do it like pros).
So, the generator is getting pulled out, and a compartment for LiFePO4 batteries is going in it's place.

The hardtop will be removed, and a frame built to hold ten commercial panels. I am aiming for >4000w of solar. Hopefully, bifacial panels will be a significant improvement over ten 400w regular panels.

A Victron 48vdc charge controller / 230vac inverter will both charge the batteries and run a 3-zone mini-split AC system. A 110vac inverter will power the outlets and fridge, microwave, coffee maker, TV, etc. There will be converters to step the voltage down to 12v at the panels for lights, instruments, etc.

The battery bank will start with 16 Eve 310AH cells wired for 48v. This might be increased to 32 cells if more capacity is needed.

Wish me luck!
 

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Double check that your use of a 50Hz EU spec Victron will work. The blower system is likely 120VAC, and it likely shares a neutral in common with the 240VAC system, or it directly specifies that it should use L1/N from the same source.

I believe most Most units require split phase 120/240V to work properly. Going with the EU spec inverter and the Victron Auto transformer might work better. Not uncommon to specify 60Hz and bump up to 240VAC. Add Autotransformer to provide 120/240VAC, and you can eliminate the 2nd inverter.

16kWh is pretty light battery for a presumably demanding A/C system.

Good luck.
 
Double check that your use of a 50Hz EU spec Victron will work. The blower system is likely 120VAC, and it likely shares a neutral in common with the 240VAC system, or it directly specifies that it should use L1/N from the same source.

I believe most Most units require split phase 120/240V to work properly. Going with the EU spec inverter and the Victron Auto transformer might work better. Not uncommon to specify 60Hz and bump up to 240VAC. Add Autotransformer to provide 120/240VAC, and you can eliminate the 2nd inverter.

16kWh is pretty light battery for a presumably demanding A/C system.

Good luck.
Somewhere I read that the inverter was selectable to 60Hz. If not, maybe I'll call them and ask "why the hell not?" ?

The point of using the mini-split is that it is energy efficient (670w-3210w). It shouldn't have to run at full capacity overnight, and the solar panels should be able to keep up during the day with power to spare for recharging the batteries and running the other, intermittent loads. I will also be insulating and adding shade to reduce the heat load the AC has to cope with.
 
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From my limited knowledge of bifacial panels they do best at higher angles so there is more room for reflected light underneath. I am not sure how you are planning to mount them but bear that in mind.

I agree that 16kwh seems a little light on the battery side of things but if you need more you can put more. It will be interesting to see how much you actually get from your 4kW of panels as they will not be at ideal angles and directions. Please report how it all works out!
 
Somewhere I read that the inverter was selectable to 60Hz. If not, maybe I'll call them and ask "why the hell not?" ?

The point of using the mini-split is that it is energy efficient (1400w-3530w). It shouldn't have to run at full capacity overnight, and the solar panels should be able to keep up during the day with power to spare for recharging the batteries and running the other, intermittent loads. I will also be insulating and adding shade to reduce the heat load the AC has to cope with.

Agreed. Mini-split is the way to go.

Again, I'm not confident that your mini-split will work with single-phase 240VAC power at 60Hz. It likely draws off L1 for the blower for 120VAC power and you NEED 120/240VAC split phase. Ask the manufacturer and/or look at the wiring diagram in the installation manual. My proposal of a Victron Autotransformer taking your 240VAC single phase and providing 120/240VAC split phase will work, and you'll only need the one inverter.
 
From my limited knowledge of bifacial panels they do best at higher angles so there is more room for reflected light underneath. I am not sure how you are planning to mount them but bear that in mind.

I think Will demonstrated this pretty effectively in his video.

I agree that 16kwh seems a little light on the battery side of things but if you need more you can put more. It will be interesting to see how much you actually get from your 4kW of panels as they will not be at ideal angles and directions. Please report how it all works out!

Same. if he can get the heat load down to the lower wattages the unit can run at in maintaining the temp, it should be good.
 
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Attached are the specs and wiring diagrams I could find from the User and Installation manuals. The boat is nominally 40'x14', but as it is not square, the interior dimensions are really a good bit smaller. Also, the volume of the spaces is less, with ceiling heights closer to 6'6" in most places. I choose the 3-zone unit so I can put an air handler in the forward cabin, main (central) cabin, and aft cabin. BTU-wise, it's overkill, but I know this will never be as well insulated as a house.

Regarding the angles of bifacial panels:
Horizontal should work just fine on a boat that basically floats on a giant, faceted mirror.

I could just save myself a lot of time and effort and money, and get used to sweating instead ? But... where would be the fun in that?!
 
Looks like that works. The unit I saw was not 3 zone, and it needed 120V for the single "air handler."

Still worth considering an autotransformer for 120/240V split phase for your 120V loads rather than a second inverter. Inverters burn power just by being on. The Quattro 5K is about 30W, and it's not a slouch compared to some.

Horizontal panels do not perform particularly well, bi-facial or not. Rare that you'll get peak performance unless the sun is actually straight above you.
 
Horizontal panels do not perform particularly well, bi-facial or not. Rare that you'll get peak performance unless the sun is actually straight above you.
With a boat, there is no guarantee that it will be facing any particular way with relation to the sun. Under power, I'll be facing whichever way I need to go. At anchor, I'll be facing into the wind.
Tilting a 500# array that doubles as the cockpit roof is an added complexity that I am not ready to deal with.

While in FL, panels often outproduce their ratings, even when laid flat. We're fairly close to the equator (sub-tropical). When I journey further north, I'm sure it will become less efficient. Of course, the further north I go, the less load will be placed on the AC, and thus less draw on the batteries. It'll all work out ??
 
Looks like that works. The unit I saw was not 3 zone, and it needed 120V for the single "air handler."

Still worth considering an autotransformer for 120/240V split phase for your 120V loads rather than a second inverter. Inverters burn power just by being on. The Quattro 5K is about 30W, and it's not a slouch compared to some.

Horizontal panels do not perform particularly well, bi-facial or not. Rare that you'll get peak performance unless the sun is actually straight above you.
I would like to see the specs on the inverter you found that requires a neutral... none I have installed do...
 
With a boat, there is no guarantee that it will be facing any particular way with relation to the sun. Under power, I'll be facing whichever way I need to go. At anchor, I'll be facing into the wind.
Tilting a 500# array that doubles as the cockpit roof is an added complexity that I am not ready to deal with.

While in FL, panels often outproduce their ratings, even when laid flat. We're fairly close to the equator (sub-tropical). When I journey further north, I'm sure it will become less efficient. Of course, the further north I go, the less load will be placed on the AC, and thus less draw on the batteries. It'll all work out ??

Wasn't implying they should tilt, just you might not ever get 4kW from 4kW of panels. Sounds like you have a good handle on it.
 
I would like to see the specs on the inverter you found that requires a neutral... none I have installed do...

I think I've said something that conveyed something else. I can't see that I said an inverter requires a neutral.

I was referring to a 230VAC mini-split that still required 120V from L1 and N for the blower.
 
I think I've said something that conveyed something else. I can't see that I said an inverter requires a neutral.

I was referring to a 230VAC mini-split that still required 120V from L1 and N for the blower.
Sorry, I meant inverter drive minisplit...
 
Yeah, the water may get you some more juice on the bifacials. I still doubt that the juice will be worth the squeeze but there is only one way to find out. Very true that you are pretty close to the equator and horizontal should work well. I'd love to see pics and progress!
 
Sorry, I meant inverter drive minisplit...

I've been searching for the conversation and the model referenced, but I can't find it. What stood out is the manual specifically showed two wiring diagrams, and the interior unit HAD to be on L1.
 
And odds are good, I will be mistaken...

Nope. You are completely right as the expectation of "HVAC" and "electrician" in your signature would suggest.

I found it. I read it wrong. I was wrong earlier in this thread. I'm ashamed. ?

Shutting up now.
 
The hardtop will be removed... Hopefully, bifacial panels will be a significant improvement over ten 400w regular panels.
To echo what boondox said, Bifacial panels require a bit of elevation off the deck, from your comments above the panels going to be the "new roof"? Hope to see photos of your setup!

I always thought the albedo of seawater (0.06) just couldn't be accurate in real conditions, so hopefully, you'll capture and share your real-life data. I'm, sure your deck will be white, so that should up the overall albedo.

There's no downside to bifacials regardless as long as the price is the same/close to regular panels. In fact, they're typically "double-sealed" so should be an excellent fit for the corrosive environment.

Horizontal panels do not perform particularly well, bi-facial or not. Rare that you'll get peak performance unless the sun is actually straight above you.
Flat is generally the only acceptable tilt for Florida just because most areas are HVHZ. But flat isn't so bad.

On the summer solstice here in the keys the sun is at 88° elevation, so flat is about 0% loss. Technically it's not the best elevation though as summer is also usually full of decorative white or black shade clouds. According to SAM, by being flat I lose about 8% power annually.

Wish me luck!
Good luck!
 
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