Solar Panels - Bimini or Davits - Pros and Cons of Both

[Boracay]

What got me thinking was that we're running two 40 litre Waecos. One as fridge and one as freezer. At the moment the freezer holds enough for a week and looks like it could hold 4 weeks worth for two persons (I did pre freeze).

They run off 4 T105s so I'm estimating I have about 400 amp/hours with about 200 to play with.

Being on the boat full time, with radio, TV, computer, lighting(mostly LEDs), and a few extras the batteries stay over 11.9 (which is my freak out point) volts for over two days. After that I need to do some serious charging.

At the moment I have two 40W panels which takes the edge off demand. I'm planning to add 4 more (for a total of 240W) which should cover the worst of what we use, but I'll probably still have to charge every few days; might get away with a week if I'm lucky.

[nwdiver]

These are the most energy efficient frigs and freezes you will find, they are normally used in off grid situations but would work on boats as well, they show one installed on a boat. They are expensive but very long lived I know of very old ones still operating off grid that have outlived a generation of solar panels.
http://sunfrost.com/index.html

[sctpc]

Originally Posted by jm21

I keep reading that gas/kerosene fridges are extremely unsafe on a mono due to the heeling motion? Maybe that fear is overblown?

I looked at the evaporative/swamp coolers but they seem to perform very poorly in areas with high humidity.

That`s fair enough I think you should way risk.
Qld is not much good for evap

But Qld is also one off the best solar environments with a 6hr rating so maybe you can survive with mainly solar and a small genny for topups and hot water.
Solar Mapping

[mbianka]

Originally Posted by COLINFLTENG

How did you secure panel ? To the deck how many MPPT controllers did you use?

I'm using a single standard Morningstar PS-15 controller for the 12 volt side and 48 volt one for the electric propulsion bank. I never felt MPPT was worth the extra cost. This system provides all the power I need including running a Engel in freezer mode.

As for mounting the panels in the end I just used eye straps and some 1/4" aluminium bar and put the panels on top and bolted them in place. A simple but, effective solution. This was an evolving design process over several years that you can see here:

SOLAR BIMINI
THE BIANKA LOG BLOG: SOLAR BIMINI: PART ONE: Plan A!
THE BIANKA LOG BLOG: SOLAR BIMINI: PART TWO: Plan B!
THE BIANKA LOG BLOG: SOLAR BIMINI PART THREE: A plan comes together!
THE BIANKA LOG BLOG: SOLAR BIMINI PART FOUR: Locating and trimming the rear frame
THE BIANKA LOG BLOG: SOLAR BIMINI PART FIVE: Useful stuff: Filament Tape
THE BIANKA LOG BLOG: SOLAR BIMINI PART SIX: DECK WORK
THE BIANKA LOG BLOG: SOLAR BIMINI PART SEVEN: PANELS INSTALLED

[jm21]

Originally Posted by mbianka

I'm using a single standard Morningstar PS-15 controller for the 12 volt side and 48 volt one for the electric propulsion bank. I never felt MPPT was worth the extra cost. This system provides all the power I need including running a Engel in freezer mode.

As for mounting the panels in the end I just used eye straps and some 1/4" aluminium bar and put the panels on top and bolted them in place. A simple but, effective solution. This was an evolving design process over several years that you can see here:

SOLAR BIMINI
THE BIANKA LOG BLOG: SOLAR BIMINI: PART ONE: Plan A!
THE BIANKA LOG BLOG: SOLAR BIMINI: PART TWO: Plan B!
THE BIANKA LOG BLOG: SOLAR BIMINI PART THREE: A plan comes together!
THE BIANKA LOG BLOG: SOLAR BIMINI PART FOUR: Locating and trimming the rear frame
THE BIANKA LOG BLOG: SOLAR BIMINI PART FIVE: Useful stuff: Filament Tape
THE BIANKA LOG BLOG: SOLAR BIMINI PART SIX: DECK WORK
THE BIANKA LOG BLOG: SOLAR BIMINI PART SEVEN: PANELS INSTALLED

With that set up, do you have many problems with shading from the boom?

[mbianka]

Originally Posted by jm21

With that set up, do you have many problems with shading from the boom?

Yes, there is some boom shadow. But, the forward panels still have plenty of sunlight to provide for my house power needs including the Engel freezer. The rear 48 volt panels are amorphus panels and are less affected by shadows. If I was more anal I could move the boom off to the side but, never felt the need to. Of course under sail the panels are fully exposed if you are on the right tack. I figure the money I saved in not having to repair or replace the dodger and bimini fabric every few years pays for the panels in short order which should last for a decade or two. To me it's a win win situation.

[ka4wja]

jm21,
1) Maybe I'm misreading/misunderstanding what you wrote.....

Originally Posted by jm21

My wife and I will have much higher than normal power needs, at least so it would appear. We want to try living on a monohull sailboat for a couple years and see how things go. But she wants a big freezer and I would have a virtual office that would require quite a bit of electronics being run for 30-40 hours per week. Calculating things out, it seems like we should plan for somewhere in the neighborhood of 2.5kwh energy use per day on average to be really safe.

....But, 2.5kwh = 2500 watt hours = 200 A/H, at 12.5 volts, etc.
And, while 200 A/H per day is on the high side of the "typical" cruising energy budget, it IS still in the "typical" range, and this consumption CAN quite easily be balanced with charging/energy replenishment from a solar array....
Yes, a larger than "typical" sized array, of approx. 500 - 600 watts, depending on our cruising locations and placement of the solar panels (no shading / adequate ventiliation / etc.)...
And while I personally agree with other posters that you get what you pay for, I further believe that spending a bit more for panels that FIT the space you have without being shaded, etc. is a VERY important and should not be overlooked!!!

{With a decent sized solar array (500-600 watts) and house battery bank, you should be easily capable of maintaining a "large" freezer (and fridge), as I do with 5 cu ft freezer and 5 cu ft frig, in the tropics, Bahamas, Florida....assumming you do it correctly (LOTS of good-quality insulation, efficient 12vdc units, etc.).....as well as have enough power for your boat "office" w/ computers, etc...}

Meaning, choose your panels for your solar array that fit the 3 big criteria:
a) YOUR energy budget / energy generation requirements (taking into consideration sun angles, any shading, cloudy days, etc.)
b) YOUR space (and shapes) available to SECURELY mount/install the panels (taking into account shading, adequate airflow around and UNDER the panels, as well as making sure that you're still able to SAIL effectively!!)
c) YOUR financial budget.....'nuf said!

With the above in mind, three 235 watt panels would NOT be my choice....(I personally love Kyocera panels, esp. the KC-135 panels....)
But, no matter what panels you decide on, you shouldn't need to support more than 100 - 150 lbs, for a 500 - 750 watt array (ballpark estimate)...





2) I'm also somwhat confused by the references to the necessity of a super-sized array of six to seven 235 watt panels!!!

Originally Posted by jm21

At least 3 but preferably more 235w panels (the more the better, 6-7 would be ideal as it would allow us to run AC on hot days for a couple hours).

That's 1410 - 1645 watts of panels, which on a sunny day in low latitudes would generate more than 7.5kwh per day....600-700 A/H per day...
Which in theory could be used to provide a great deal of power / lots of battery charging (IF you have a VERY large battery bank), and also which in therory could be used to power a small air cond unit....
BUT...
But this is only possible in theory as I've never seen anyone actually do this in real life (read some posts from those who deisred/attempted it, but never one word from anyone who has accomplished it), not the least of which is because, once away from the dock/marina there is little / no need for air cond!!

Bottom line:
Even the most efficient 12vdc air cond units (there aren't really very many out there, so "most efficient" is probably a "relative" term), will use 45 amps or so from 12vdc, for a small 5000 BTU unit (which is TOO small to cool anything but one SMALL cabin)....
And, trying to use a 110vac unit, with an inverter, introduces inverter losses, etc....

So, in my opinion, running air cond. should NOT be included into your daily energy budget.....you're NEVER going to do it on battery power, and you'd need a HUGE solar array (and a huge battery bank) to attempt it from solar energy, as well as your typical 45' sailboat needing approx 30,000 BTU's of cooling in hot climates...(I have 33,000 BTU's on my 47' sloop, which works at the dock in Florida in the summertime...)
If you're at the dock, and need/desire air cond, then you have SHORE POWER.....if you're away from the dock/shore power, you'll probably never need air cond....as long as you keep your boat ventilated well (hatches, opening ports, winds scoops, and lots of fans!!) and keep your boat shaded from the sun!!!








3) As for "temporary" panels, etc....

Originally Posted by jm21

You could fit solar panels to this while at anchor, and when moving the boat long distances, either remove the panels or reduce the number of panels and use it as a dinghy davit.

In my opinin, this is a non-starter!!!!
It just doesn't work....
Here are jus some of the issues:
a) "where" and "how" to mount them....so they are "secure" (even necessary at anchor), unshaded, and not in the way of your life on-board???
b) "where" and "how" are you going to stow / store them when underway....(there is already never enough room on-board most boats!!)
c) "who" is going to spend the time / effort to mount/install/wire-up and then remove/un-install/disconnect them all the time???
d) "how" are you going to keep the wiring connections clean and free from corrosion, and still be able to connect/disconnect them effectively????

I think you see just some of the issues!!!

{In all fairness, I have persoanlly seen a couple living on-board a smallish sailboat (~ 30 footer), with one large (175 watt I think) panel, that they plugged-in and "stuck in the cockpit" every morning as they went to shore, and un-pugged and lashed to their lifelines every evening....while this worked for them, their live-aboard life and shoreside work-life, and their very small energy needs, it is not something that would work for most!!!}








4) Starting in 2004 thru 2006, in addition to the often recommended LED lighting (I used mostly Sensi-Bulbs and Sylvania MR16 LED's), and LED NAV Lights (I used OGM's)....I added significant additional insulation to my frig/frezzer units, about a dozen 12 vdc fans, etc....as well as a large solar array, etc..

If you're interested in what I did for my 520 watt solar array, refrigeration, fans, bimini, etc...
Have a look at these pages....(all of these have worked very well, and survived for 6 years now, 12,000 miles offshore, including 2 Atlantic crossings, multiple full gales, etc..)
Solar Panels
Towed-Water-Generator
Frig/Freezer
12 Volt Fans
Nav Station
Watermaker
Battery
Bimini
E120/Cockpit




I do hope this helps...

John
s/v Annie Laurie

[sailinglegend]

Originally Posted by ka4wja

.....Which in theory could be used to provide a great deal of power / lots of battery charging (IF you have a VERY large battery bank), and also which in therory could be used to power a small air cond unit....
BUT...
But this is only possible in theory as I've never seen anyone actually do this in real life (read some posts from those who deisred/attempted it, but never one word from anyone who has accomplished it), not the least of which is because, once away from the dock/marina there is little / no need for air cond!!

Forget the theory we run our 12,000 Btu air con for a couple of hours from our 1050 Ah battery bank via a Victron inverter. In Turkey at midnight it is still over 30 degrees at anchor.

We charge at 280 amps from a Fischer Panda 12 volt DC genset. At the moment we only have 150 watts of solar, but still only run the genset about every two weeks.

[ka4wja]

sailinglegend,
Congrats!!!

I humbly stand corrected.....
You are the very first sailor I've heard of that has actually run air cond units from batteries!!!
(and I started my cruising/voyaging as a kid in the mid 1960's!!!)

So, to jm21....it appears it has been done by someone!!!


Fair winds...

John
s/v Annie Laurie

[Ram]

Originally Posted by ka4wja

jm21,
1) Maybe I'm misreading/misunderstanding what you wrote.....
....But, 2.5kwh = 2500 watt hours = 200 A/H, at 12.5 volts, etc.
And, while 200 A/H per day is on the high side of the "typical" cruising energy budget, it IS still in the "typical" range, and this consumption CAN quite easily be balanced with charging/energy replenishment from a solar array....
Yes, a larger than "typical" sized array, of approx. 500 - 600 watts, depending on our cruising locations and placement of the solar panels (no shading / adequate ventiliation / etc.)...
And while I personally agree with other posters that you get what you pay for, I further believe that spending a bit more for panels that FIT the space you have without being shaded, etc. is a VERY important and should not be overlooked!!!

{With a decent sized solar array (500-600 watts) and house battery bank, you should be easily capable of maintaining a "large" freezer (and fridge), as I do with 5 cu ft freezer and 5 cu ft frig, in the tropics, Bahamas, Florida....assumming you do it correctly (LOTS of good-quality insulation, efficient 12vdc units, etc.).....as well as have enough power for your boat "office" w/ computers, etc...}

Meaning, choose your panels for your solar array that fit the 3 big criteria:
a) YOUR energy budget / energy generation requirements (taking into consideration sun angles, any shading, cloudy days, etc.)
b) YOUR space (and shapes) available to SECURELY mount/install the panels (taking into account shading, adequate airflow around and UNDER the panels, as well as making sure that you're still able to SAIL effectively!!)
c) YOUR financial budget.....'nuf said!

With the above in mind, three 235 watt panels would NOT be my choice....(I personally love Kyocera panels, esp. the KC-135 panels....)
But, no matter what panels you decide on, you shouldn't need to support more than 100 - 150 lbs, for a 500 - 750 watt array (ballpark estimate)...





2) I'm also somwhat confused by the references to the necessity of a super-sized array of six to seven 235 watt panels!!! That's 1410 - 1645 watts of panels, which on a sunny day in low latitudes would generate more than 7.5kwh per day....600-700 A/H per day...
Which in theory could be used to provide a great deal of power / lots of battery charging (IF you have a VERY large battery bank), and also which in therory could be used to power a small air cond unit....
BUT...
But this is only possible in theory as I've never seen anyone actually do this in real life (read some posts from those who deisred/attempted it, but never one word from anyone who has accomplished it), not the least of which is because, once away from the dock/marina there is little / no need for air cond!!

Bottom line:
Even the most efficient 12vdc air cond units (there aren't really very many out there, so "most efficient" is probably a "relative" term), will use 45 amps or so from 12vdc, for a small 5000 BTU unit (which is TOO small to cool anything but one SMALL cabin)....
And, trying to use a 110vac unit, with an inverter, introduces inverter losses, etc....

So, in my opinion, running air cond. should NOT be included into your daily energy budget.....you're NEVER going to do it on battery power, and you'd need a HUGE solar array (and a huge battery bank) to attempt it from solar energy, as well as your typical 45' sailboat needing approx 30,000 BTU's of cooling in hot climates...(I have 33,000 BTU's on my 47' sloop, which works at the dock in Florida in the summertime...)
If you're at the dock, and need/desire air cond, then you have SHORE POWER.....if you're away from the dock/shore power, you'll probably never need air cond....as long as you keep your boat ventilated well (hatches, opening ports, winds scoops, and lots of fans!!) and keep your boat shaded from the sun!!!








3) As for "temporary" panels, etc.... In my opinin, this is a non-starter!!!!
It just doesn't work....
Here are jus some of the issues:
a) "where" and "how" to mount them....so they are "secure" (even necessary at anchor), unshaded, and not in the way of your life on-board???
b) "where" and "how" are you going to stow / store them when underway....(there is already never enough room on-board most boats!!)
c) "who" is going to spend the time / effort to mount/install/wire-up and then remove/un-install/disconnect them all the time???
d) "how" are you going to keep the wiring connections clean and free from corrosion, and still be able to connect/disconnect them effectively????

I think you see just some of the issues!!!

{In all fairness, I have persoanlly seen a couple living on-board a smallish sailboat (~ 30 footer), with one large (175 watt I think) panel, that they plugged-in and "stuck in the cockpit" every morning as they went to shore, and un-pugged and lashed to their lifelines every evening....while this worked for them, their live-aboard life and shoreside work-life, and their very small energy needs, it is not something that would work for most!!!}








4) Starting in 2004 thru 2006, in addition to the often recommended LED lighting (I used mostly Sensi-Bulbs and Sylvania MR16 LED's), and LED NAV Lights (I used OGM's)....I added significant additional insulation to my frig/frezzer units, about a dozen 12 vdc fans, etc....as well as a large solar array, etc..

If you're interested in what I did for my 520 watt solar array, refrigeration, fans, bimini, etc...
Have a look at these pages....(all of these have worked very well, and survived for 6 years now, 12,000 miles offshore, including 2 Atlantic crossings, multiple full gales, etc..)
Solar Panels
Towed-Water-Generator
Frig/Freezer
12 Volt Fans
Nav Station
Watermaker
Battery
Bimini
E120/Cockpit




I do hope this helps...

John
s/v Annie Laurie

Thanks Alot John - I read it all, and is very helpful- You could write a book on this !! You mention you would not use the 230 watt panels , if you had the room would you use them -and if not why- Also the batterys if one cell goes bad you can just replace that one, even if its 5 years down the line???

[jm21]

So the consensus seems to be a smaller array that's permanently mounted and fits the space available on the specific boat. With maybe a backup fossil fuel generator just in case. Sort of what I should have figured. Probably got a little over-excited about the idea of cheap solar. But does seem like 2-3kwh of energy production per day (or a little more) is pretty feasible if one is not too picky about the cosmetic aspect. And it would be possible to do that using the cheaper 200+ watt panels using a solar bimini type set up.

And sounds like some things will be just trial and error and about our personal tastes (e.g. do fans work well enough in the tropics offshore for us?). Still hard to find a lot of solid information about the power consumption of different types of freezers/refers but I suppose we'll figure that one out eventually...and will probably depend quite a bit on what systems are on the boat we eventually buy...

[jm21]

Originally Posted by sailinglegend

Forget the theory we run our 12,000 Btu air con for a couple of hours from our 1050 Ah battery bank via a Victron inverter. In Turkey at midnight it is still over 30 degrees at anchor.

We charge at 280 amps from a Fischer Panda 12 volt DC genset. At the moment we only have 150 watts of solar, but still only run the genset about every two weeks.

What kind of batteries do you use? 1050 AH seems like a lot.

[ka4wja]

Ram,
1) You're welcome....

2) And, I have actually written many articles and pamphlets, as well as taught seminars, on various subjects...from alt energy, battery technology, maintainence etc. to radio propagation, antenna design, radio comms, etc...(all for free!!!)

3) My profressional experience with solar/battery power started 30 years ago, designing/installing off-grid systems for remote transmitter sites, etc...and then a few years after that, rigging some "surplus" solar on boats of various sizes/shapes!!!
(When MPPT controllers came around a decade ago, I thought I died and went to heaven!!)




4) As for MY panel choice....

Originally Posted by Ram

You mention you would not use the 230 watt panels , if you had the room would you use them -and if not why-

a) It was MY decision to use panels that could be directly connected to my 12 volt house battery bank, should a total failure of charge controllers occur when offshore and/or in far-flung remote areas...
And, this necessitaes "nominal 12-volt panels", which typically will have a MPP voltage of 17.5volts (and a short-circuit voltage of about 16 volts)....
A BIG battery bank will absorb the slightly higher charging voltages, without issue.....or I could shade a cell or two on each panel if needed, and still get adequate charging current....
Most all "nominal 12-volt panels" are those with rated outputs of 135 watts or lower.....those with 150-200watts or higher, are typically 32volt- 70volt panels.....(not going to be able to connect a 35 to 70 volt panel to a 12-volt battery without boiling the electrolyte!!!)

b) I chose panels sized to not only fit MY boat and MY set-up without shading....
BUT, also took into account the ability to remove and stow the panels below, when preparing for a Hurricane....(I've been thru many hurricanes over the years....and both my boat and I have survived three Cat 3 Hurricanes just in the last 8 years!!!! two of which I've been on-board for all of it!!!)

c) Understand that this is MY choice, for MY application, on MY boat, for MY cruising/voyaging.....
Others may make other choices....




3) Regarding the my 2-volt cell Rolls batteries....

Originally Posted by Ram

Also the batterys if one cell goes bad you can just replace that one, even if its 5 years down the line???

The answer is: Yes....and there is a 7 year warranty on them (pro-rated after the first 2 years).....
And each cell weighs in at about 35lbs....(lighter than even a 6-volt golf cart battery)




I hope this helps...

Fair winds...

John
s/v Annie Laurie

[Ram]

Originally Posted by ka4wja

Ram,
1) You're welcome....

2) And, I have actually written many articles and pamphlets, as well as taught seminars, on various subjects...from alt energy, battery technology, maintainence etc. to radio propagation, antenna design, radio comms, etc...(all for free!!!)

3) My profressional experience with solar/battery power started 30 years ago, designing/installing off-grid systems for remote transmitter sites, etc...and then a few years after that, rigging some "surplus" solar on boats of various sizes/shapes!!!
(When MPPT controllers came around a decade ago, I thought I died and went to heaven!!)




4) As for MY panel choice....

a) It was MY decision to use panels that could be directly connected to my 12 volt house battery bank, should a total failure of charge controllers occur when offshore and/or in far-flung remote areas...
And, this necessitaes "nominal 12-volt panels", which typically will have a MPP voltage of 17.5volts (and a short-circuit voltage of about 16 volts)....
A BIG battery bank will absorb the slightly higher charging voltages, without issue.....or I could shade a cell or two on each panel if needed, and still get adequate charging current....
Most all "nominal 12-volt panels" are those with rated outputs of 135 watts or lower.....those with 150-200watts or higher, are typically 32volt- 70volt panels.....(not going to be able to connect a 35 to 70 volt panel to a 12-volt battery without boiling the electrolyte!!!)

b) I chose panels sized to not only fit MY boat and MY set-up without shading....
BUT, also took into account the ability to remove and stow the panels below, when preparing for a Hurricane....(I've been thru many hurricanes over the years....and both my boat and I have survived three Cat 3 Hurricanes just in the last 8 years!!!! two of which I've been on-board for all of it!!!)

c) Understand that this is MY choice, for MY application, on MY boat, for MY cruising/voyaging.....
Others may make other choices....




3) Regarding the my 2-volt cell Rolls batteries....

The answer is: Yes....and there is a 7 year warranty on them (pro-rated after the first 2 years).....
And each cell weighs in at about 35lbs....(lighter than even a 6-volt golf cart battery)




I hope this helps...

Fair winds...

John
s/v Annie Laurie

Thanks Again , you have helped a lot! Posts like yours are what were all here for!- I’m in Cypress at the moment and will sail back to Florida this winter and will be installing , solar, new batteries, water maker-so you have given me some things to think about and i do appreciate it!

[sailinglegend]

Originally Posted by jm21

What kind of batteries do you use? 1050 AH seems like a lot.

5 x 210 Ah Lifeline AGMs - now 7 years old - permanent liveaboard.