Solar Upgrade verse Running the Generator

[john61ct]

No, air-cooled far better nowadays, water-cooling is a maintenance nightmare, completely unnecessary for any size is my understanding, but do need good ventilation for the electronics as well as condensers for good efficiency. Of course proper insulation is the most critical factor.

I believe plates are very different between system types.

[admiralslater]

Originally Posted by john61ct

Actually that's ideal, since your design should be based on a few overcast days in a row, still getting the bank to full.

A holding plate fridge is another good excess power load dump.

I was happy to see your post , as I am in the middle of increasing my solar capacity from 580 to 900 watts, with a bank size of 550 amperes. I use about 25 % of the capacity per day and can recover if the conditions are perfect. Last year we had a about a week of cloudy rainy weather and intermittent clouds for a week after that and the panels could not quite get us back to 100%. So my new capacity is for recovery only . I also am splitting the panels over the davits in two with 100/30 victron controllers on each and a third controller on the Bimini array

[john61ct]

Looks good!

[Exile]

Originally Posted by admiralslater

I was happy to see your post , as I am in the middle of increasing my solar capacity from 580 to 900 watts, with a bank size of 550 amperes. I use about 25 % of the capacity per day and can recover if the conditions are perfect. Last year we had a about a week of cloudy rainy weather and intermittent clouds for a week after that and the panels could not quite get us back to 100%. So my new capacity is for recovery only . I also am splitting the panels over the davits in two with 100/30 victron controllers on each and a third controller on the Bimini array

You cat guys have nothing but real estate for panels!

[Exile]

Originally Posted by a64pilot

Cool Blue is air cooled.
There is no real difference in efficiency between air cooled and water cooled. Water cooling is only required if the air cooling isn't done right.
Water cooling brings with it a host of potential problems that air cooling doesn't.

Originally Posted by john61ct

No, air-cooled far better nowadays, water-cooling is a maintenance nightmare, completely unnecessary for any size is my understanding, but do need good ventilation for the electronics as well as condensers for good efficiency. Of course proper insulation is the most critical factor.

I believe plates are very different between system types.

It sounds like the water-cooling for my refrig. unit might be better explained by the compressor & much of the copper tubing being located inside the engine compartment. Water cooling hasn't proven to be a maintenance "nightmare" in the least, but I would love to get rid of two more holes in the boat, along with the pump & associated lines, and have one less strainer to clean.

I think we also need to differentiate btwn. holding plate vs. evaporative plate systems in assessing energy consumption & other issues with modern 12v systems. It seems like evaporative/constant cycling is favored these days.

[admiralslater]

Yes exile cat sailors are very lucky in the ability to use solar which is handy because putting a gen set on a cat can be problematic. If I had turned the panels fore/aft I could have gone for 1130. As far as refrigeration is concerned take a look at posts by Coldeh and his system ,I am considering it for my self . John is a nice guy

[a64pilot]

Again, there is very little difference in efficiency between a thin walled evaporator and a cold plate, the efficiencies come from a properly sized condenser, and an expansion valve etc., but mostly by having a system that is correctly spec.

All things being equal a thin walled evaporator is more efficient as there is no medium that transfers heat. How many home sized fridges you seen with cold plates?
However a cold plate can make up for the inefficiency of having a transfer medium by allowing longer compressor cycles, longer run times and longer off times are more efficient as of course there is some time after start up before pressures stabilize, temps come down and the system operates at peak efficiency, until then, your inefficient.
But cold plates come onto their own when used as a flywheel so to speak, freeze them down during the day when Solar is excess and leave compressor off at night, or an engine driven compressor for when motoring.

I'd suspect that your compressor is way oversized with the idea of quickly freezing the plates down to a low temp when plugged in or on generator and then coasting so to speak between generator runs or shorepower being plugged in. A oversized cooling system can freeze the plates down pretty fast, a "correctly" sized one would likely take hours. Correct is in parenthesis as if efficiency is the goal, then you shoot for nearly 100% run times. This however isn't the best as when you add a whole lot of heat in the fridges say a case of hot beer, it takes days to get back to set point, you need excess cooling to get back faster.

[Exile]

Very helpful a64. Since Cool Blue also uses holding plates I'll talk to Rich B. & also Seafrost about a conversion. The challenge may be where to locate a new air-cooled compressor, i.e. getting it out of the engine room & somewhere where there's reasonable ventilation.

[john61ct]

Yes I've heard good things about Cleave, as well as OzeFridge, but dunno about added shipping expense from Aus.

http://www.coldeh.com uses Danfoss, also TXV valve, which helps efficiency like Cool Blue but he uses evaporators rather than eutectic plates.

I really like the idea of the latter, but only if you've got pretty dependable "excess power" for a few hours a day. Without that I think evaporators are the way to go, but Ozefridge does claim they're less efficient even with all else held equal.

[daletournier]

Originally Posted by john61ct

Yes I've heard good things about Cleave, as well as OzeFridge, but dunno about added shipping expense from Aus.

http://www.coldeh.com uses Danfoss, also TXV valve, which helps efficiency like Cool Blue but he uses evaporators rather than eutectic plates.

I really like the idea of the latter, but only if you've got pretty dependable "excess power" for a few hours a day. Without that I think evaporators are the way to go, but Ozefridge does claim they're less efficient even with all else held equal.

I had a ozefridge on the last boat. I really liked being able to turnnit on manually utilizing excess power generation ,either through alternator or solar ie. Reduced overall power consumption.

[foggysail]

Originally Posted by Exile

It sounds like the water-cooling for my refrig. unit might be better explained by the compressor & much of the copper tubing being located inside the engine compartment. Water cooling hasn't proven to be a maintenance "nightmare" in the least, but I would love to get rid of two more holes in the boat, along with the pump & associated lines, and have one less strainer to clean.

Yeah, have to agree with your maintenance experience. I don't know of any marine air conditioners that use air for heat transfer......OK, sure somebody will come back naming a dozen or so that use air

[a64pilot]

Originally Posted by foggysail

Yeah, have to agree with your maintenance experience. I don't know of any marine air conditioners that use air for heat transfer......OK, sure somebody will come back naming a dozen or so that use air

That is only due to packaging constraints.
By that I mean of course by being water cooled you can have a small package and locate it pretty much anywhere in the boat and plumb water to it.
Air cooled and you would have to have likely as much as 1 cu ft air duct as you need air to flow both ways of course.
You could mount the condenser outside, but that would be ugly and have it out in salt spray.
However look at nearly all Commercial boats and you will see they almost all have RV type roof mount AC's. They don't care as much about aesthetics, they just want an AC that works, and as inexpensive as possible.

Years ago ground source heat pumps were all the rage for houses as of course they were more efficient, however they have pretty much all gone away, they were a little more efficient, but the extra expense with water pumps and all mitigated that.
Most of their efficiency came from the fact that for example where I lived you had 68F water to heat and cool with all year long, where in Summer you cooled with 90+ degree air and in winter you used freezing air to heat with.

I had two unused wells at my last house so I had the infrastructure for a ground source heat pump, but didn't go that way.

[foggysail]

YOU can call efficiency anything you want. Been awhile since my days in a thermodynamics class in college, this I remember well though; maximum heat transfer is governed by T1-T2 where T1 is the heat source temperature and T2 is the temperature of the substance where heat is transferred to. The greater the temperature difference, the greater the heat transfer.

And by all means, 80F water is still colder than a 90F condenser and even greater heat transfer will occur if the water temperature is 60F. A water cooled system will always have a higher efficiency that an air cooled system.

[a64pilot]

The efficiency is there with ground source of course, more so because the water source is a constant temp, year round. South Ga it's 68 degrees F. When it gets cold, there isn't enough heat in the cold air to run a heat pump so it goes to heat strips, which are very inefficient, a ground source pump keeps running of course.
However the water pumps and the associated maintenance eats into the savings, enough so that apparently the pay back is a long time

[foggysail]

Originally Posted by a64pilot

The efficiency is there with ground source of course, more so because the water source is a constant temp, year round. South Ga it's 68 degrees F. When it gets cold, there isn't enough heat in the cold air to run a heat pump so it goes to heat strips, which are very inefficient, a ground source pump keeps running of course.
However the water pumps and the associated maintenance eats into the savings, enough so that apparently the pay back is a long time

That is clear..... no misunderstanding and I agree with you!!!