A household fridge running on solar panels

Solar Powered Refrigerators
I have a 19.5 cu. ft. GE no frost refrigerator/freezer (Model TFX20RH) built in 1987 aboard my boat. On May 20, 2010 I tested the power consumption using a Kill-A-Watt meter. The test lasted 67 hours (2.8 days) with a power consumption of 9.54 kWh (142 watts average). Temperature of the interior of the boat was 70-80F and temp of the interior of the fridge was about 45F. The freezer part was about 25F.
So a typical 20 cu. ft. mid 80s refrigerator burns about 140 watts at 120 volts. Today similar fridges are much more efficient with power consumptions of as little as 50 watts.
So if you are trying to solar power a refrigerator figure 50 watts for a new 20 cu. ft refrigerator. If you've got an old beastie refrigerator from the 80s figure nearly triple that. So the obvious answer from the standpoint of keeping the solar panels small (and cheap) is to buy an effiicient new fridge. The cost of a good 20 cubic foot refrigerator/freezer can be as much as $1,400. But if you can cut back on the frills and size a good fridge using as little as $25 watts can be had for under $500.
Happy Shopping
Pete37, 10/09/2013

50 watts at 12V is about 4 amps , figure 5 for wiring and inverter losses.

At 24 hours a day thats 120 amp hours , which requires 240 AH batteries on a cloudy day.

Simply replacing 120 AH will require 150AH of solar or wind as batterys need energy to be charged.

Solar can work , but its a challenge , not a bolt on task.

To shop for a fridge there will be an annual KW number on the new units , simply divide by 365 to find the KW per day.

This is a very LOW estimate as most thin wall insulation in modern fridges require heating strips to defrost the insulation , and door seal.

And of course the unit mfg have permission NOT to count this power in the annual.

K Street $$$$$$$ wins again

Yes, you can power the fridge using solar. I recommend shopping for the latest refrigerator/freezers made in Japan such as Hitachi. These units are super efficient with multiple doors and drawers to avoid heating up each time you open up for a cold beer. Using the annual cost figures (yellow tag), you can estimate daily watts - our 14 civic foot Uses about 35 watts/hour.

Second - get efficient inverter - as close to 90% as possible.

Third - if space for PV array is generous, you can install less expensive, less efficient panels. We have Sun Power , the most efficient. We feet our chargers at 80v by pairing the panels.

Fourth. If your budget allows, use LiFePo lithium cells to make as big a battery as space allows. The cost of ownership of a LI battery is less than AGM if you use it. Compare less than 500 lifetime cycles vs. over 3,000 for the LI.

Our DSe "Sunshine" has 6,000 watts of solar, 2 each Outback 60 amp controller chargers, 2 each Outback 3.6 kW inverters and 1,000 AH/48v LI battery. All domestic power is sun generated including induction cooktops, air conditioning, refrigeration, pumps, hot water, washer-dryer, entertainment system and LED lighting.

The key to a successful system is doing the math up front. More battery is better than less. A bit of wind power is a good idea, too.

Shore Power Independence
You guys who are trying to run your boats totally on solar power thereby eliminating the generator are missing the point. Nearly all modern motoryachts are already equipped with a generator. And solar cells don’t provide enough power for the galley loads, water heating or air conditioning. What you really want is called shore power independence; the ability to operate your yacht away from shore power cables attached to a dock.

My Connie is already shore power independent. It has a 20 KW generator and 600 gallon fuel tanks. If I reserve 200 gallons for the engines, that leaves me with 400 gallons for the genny. It burns about 1.0 gph at full load. But at half load (10 KW) it only burns about ½ gph. So at half load I can stay away from the dock for 400/0.5 = 800 hours. That’s almost 33 days of continuous running. But during the evening I burn very little power (probably less than ¼ of full load) so with a little effort to conserve power I can probably stay away from the dock for 45 days (a month and a half).

But by now you guys are probably saying “Who the hell wants to put up with the noise, vibration, fumes and smell of a diesel genny operating 24/7 for a month and a half?” The answer is “Not me!”

How do I get around it? The answer is I run the genny only 8 hours a day at meal times; breakfast, lunch, dinner and midnight snack. And while I am running the genny I take care of charging a 480 AH set of four 6 volt 120 AH golf cart batteries. With a 3 kW inverter this battery bank takes care of all the 120 volt AC loads during the periods when the genny is off.

The genny has to be on at all meal times anyway to handle the galley loads (unless you are willing to survive on baloney sandwiches). With 20kW to work with I can easily take care of all the other high power loads, water heating, clothes washing/drying, battery charging, partial air condition, etc. Windmills and solar panels? I don’t need them and I don’t want to pay for them. I don’t think that most of you that have generators need them either.

For those of you heavily into the shore power independence kick I recommend The Voyager’s Handbook. This is a book written by blue water cruisers who cross oceans and circumnavigate the world. They obviously have to be shore power independent. It’s a 570 page tome filled with graphs, figures and pictures which describes just about anything you would want to know about ocean voyaging and shore power independence. I bought my copy in 2011 for $42.35.

Pete37

Pete. This thread started with the question can one run a fridge using only solar power and avoid the need to install a generator. The skipper asking obviously doesn't have a generator at present and is seeking an alternate solution.

As you say, most yachts come with a generator and yours has a. 20 kW. Of course, the path of least resistance for you and most others is to simply turn on the generator when needed, rationing power when it 'a off. Makes sense.

The question was can the jobless be done and is it being done with solar in the absence of an on board diesel or gas generator.

And the answer is,"YES!"

In addition, cooking, air conditioning and other domestic tasks can also be done using solar alone, or solar plus other forms of power generation.

One last thing, your 400 gallons of diesel is over $1,500 each time you replace it and your generator is a bit noisier than solar. I'm not suggesting you invest the time and effort to convert, but for someone starting with a clean sheet of paper , solar and wind are viable alternatives for some boaters.

Running Household Fridges on Solar Panels

A previous post asked the question “Can you run a household fridge on solar panels?” I assumed that what he meant was “Is it practical to run a household fridge on solar panels?” Obviously, if you have unlimited money you can run the fridge on solar panels. But few of us have unlimited funds. I’ll try to answer that question in the following paragraphs.

A 100 watt Sunforce Solar Panel costs about $360 (West Marine). The realistic daily output from four of these panels in bright sunlight in the tropics is about 100 AH @12 V (p235, Voyagers Handbook). This assumes that the orientation of the panel is nearly perpendicular to the surface of the panel. That’s not too difficult to do on land but on a rapidly moving boat you can only expect about half that amount (50 AH). 50AH at 12 volts is 5 AH at 120 volts or 600 watt hours (0.6 kWh). An efficient 20 cu. ft. refrigerator/freezer burns about 60 watts and over a 24 hour day it will burn 1440 watt hours or 1.44 kWh. So just to keep up with the refrigerator’s load you will need about (1.44/0.6) x4 = 9.6 panels at a cost of 9.6 x $360= $3,456. And this is in the tropics. In the mid-latitudes the array and its cost might have to be twice as large.

Each panel is about 4’ x 2’ so your total array is about 8’ x 4’ and must be mounted on a two axis gimbal to keep it perpendicular to the incoming solar radiation. To keep the solar array size manageable you are probably going to have to reduce the area by a factor of two making it about 2.82’ x 5.6’; still a pretty unwieldy array; particularly in a 20 knot breeze. And since the area of the array is only half as much you’re are going to have to reduce the size of the refrigerator to something like 10 cubic feet; Not exactly household size; more like picnic size.

The reduced array size will fortunately reduce the cost of the panels but the cost of a custom made two axis steerable mount will more than eat up those savings. I think the whole array system (panels plus mount) would cost $3k to $4k. And add in $800 for a bank of batteries/battery charger/inverter system plus another $600 for the fridge and you’re well over $5,000.

Logistically, steering the array is going to be a major problem. The boat is pitching, rolling and yawing but if you don’t keep the array nearly normal to the incoming solar radiation the power drops off dramatically. In dead calms steering the array may not be a problem but in any type of sea steering the array will require a second helmsman. You’ve got to steer the array as well as the boat.

And of course at sea you can have several days (perhaps even occasionally a week) of cloudy weather when the solar panels will produce next to nothing. This will require a huge battery bank to store enough battery power to get you through these periods.

The answer to the question “Can you run a refrigerator solely on solar cells?” is “Yes”; provided you have a large enough array and enough money to pay for the solar array and all its accessories”. If you asked me whether it was practical the answer would be a resounding “No”. A generator would be cheaper, more reliable and more practical. Plus, It can run 24/7 regardless of the weather.

Pete37

rjtrane said:

Pete. This thread started with the question can one run a fridge using only solar power and avoid the need to install a generator. The skipper asking obviously doesn't have a generator at present and is seeking an alternate solution.

As you say, most yachts come with a generator and yours has a. 20 kW. Of course, the path of least resistance for you and most others is to simply turn on the generator when needed, rationing power when it 'a off. Makes sense.

The question was can the jobless be done and is it being done with solar in the absence of an on board diesel or gas generator.

And the answer is,"YES!"

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Thanks for the valuable information provided.

The vessel will be based and cruised in Northern Australia and SEAsia, so equatorial waters

The vessel I was looking at had a genset, but it didnt work and was in need of rebuild.
Rebuild costs in Australia would certainly run into the $5's if not $10's of thousands and buying a new one would probably be more viable.
Then there is daily fuel usage

200watt solar panels are available on ebay here for as little as $200 (possibly even $160 Click Here
An efficient 300 to 400 litre 240v fridge freezer is available for around $1000 - $1500 here.

An efficient 12 volt fridge freezer is $3000 plus here and looks like a 1960's icebox.
Also it would only be 120 litre, so 2 if not 3 would be required.
3 things to go wrong and a $10,000 purchase price.
If going no solar add in $15 to $20,000 for Genset

That buys a hell of a lot of $200 panels for running that less efficient fridge freezer and when/if it gives problems WORST case scenario is I throw the fridge away and spend another $1500.
The 12 volt fridges may cause all sorts of problems, my cruising observations would show marine refrigeration issues to be very common, so spending large dollars on a potentially troublesome item to me makes little sense.

Since I've already spent a great deal of money and time to transfer my genset to a new hatch under the veranda from it's hell hole under the galley, I've no intention of getting rid of it, but I've also spent an equal amount of time and money re-skinning my roof and clearing it of other devices for solar panels only. My plan is for installing 1340 Watts of panels to drive my Dometic fridge, pumps, lights, and to charge my two 8D house batteries till they wear out and I change them out for LI units as Rubin suggests. Of course, I'm in FL and that means a lot. I'll run the genset for A/C. Hot water will come from another solar panel and insulated storage tank specific to that need.

With todays tech, it seems to me that reasonably economic compromises in appliances and solar/wind are becoming abundant the same time (thanks to China), especially in relation to the overall cost of boat ownership. The points that Pete has made about direct sunlight are legit, but panel design is improving. I'm looking forward to the day that I have to start and run my genset as a maintenance requirement rather than a need.

The state of the art fridges from japan such as the hitachi use inverter technology for their variable speed compressors maximizing efficiency. And typically, a household fridge runs years without any service.

Look closely at building a LI-Ion battery - cost is about $1/AH (3.3v cells - $4/AH at 12v). This is about 2 times the cost of the best AGM batteries but is about 40% the mass (per AH) and has 6 to 10 times the life expectancy in cycles. 400 AH at 12v should be enough. More is better. The bigger the battery, the less wasted solar energy. With a lithium battery, you'll need a battery management system - ideally one that can communicate with solar chargers AND the inverter (Victron makes one that does this).

Sun Seeker Lite is an iPhone app that calculates the elevation of the sun during the day depending on your latitude. You can take this info and calculate the angles of the sun from the vertical. This is the angle the sun hits the panels assuming the panels are mounted flat. (The only practical way). Take the cosine of this angle and multiple by the rating of the panel. This gives you the maximum possible output of the panel.

I feel you actually will see about 50% to 75% of this number of real useable power. Based on your latitude and number of sunny days, you should be able to get a good idea how big the PV array needs to be. Again, err on more rather than less, depending on space requirements.

I think Victron also has solar controller/chargers?

We used AGM batteries for 4 seasons. They wee OK. Last year we replaced with Li-Ion which is fantastic. We now have a single 48v/1,000 AH battery that weighs 1,250# (same weight as 400 AH AGM).

Hi Reuben,

Your right that household fridges last a long time. My GE refrigerator/freezer on the boat is 27 years old and running fine. And I have another (not on the boat) that's even older. The problem with the old fridges is not longevity it's that they're not efficient. So I should change the old fridge out. But that costs about $1500 for the new fridge plus another $500 for removal of the old unit and installation of the new. But as long as I charge the batteries with a generator, efficiency isn't important so I guess I'll continue to use the old fridge until it craps out.

My ordinary wet lead acid batteries last about 8 years so even with old technology I'm not worried about lifetime. And at $200 for a 12V 250 AH 8D ($0.80/AH) they're cheap. Building a LI-ION battery might be an interesting hobby project but I really don't need one. The old batteries work fine. If I were launching my batteries into space weight would be important but on a 54,000 lb. boat the weight is noise level. And again, since I'm charging the batteries with a generator, maximum efficiency isn't important. And my old lead acid batteries don't need a battery management system.

I have tables from Bowditch that give the elevation of the sun. Not as cute as the app but it works and since I don't have an iphone they may work better anyway. But thanks for the tip.

Putting your solar array on a flat horizontal surface makes a lot of sense. That way you don't have to steer the array; a big cost saving. But the only semi-flat horizontal surface I have for the array is the top of the lower salon which gets a hell of a lot of salt spray and it also means that in the early morning and late afternoon your array is essentially useless. Horizontal arrays only give you about 6 to 8 hours a day of useful output. Plus, it's my wife's favorite place to sunbathe. I may have problems kicking her out. But if I can evict my wife I may try the horizontal array route. The steerable array while more efficient is a logistical bummer. But again, as long as I charge my batteries with the genny I don't need a solar array so perhaps my wife can keep her sunbathing spot.

I'm getting older and lifting out the 135 lb. 8Ds is beginning to be a problem. If they were in an easily accessible place lifting them out wouldn't be a problem. But they aren't and I'm finding that hiring a $10 an hour grunt to help me with the batteries is a lot cheaper than a trip to the doctor. How the hell do you get a 1,250 lb battery out of the boat? I'm assuming it comes out in pieces. Or do you have a special crane?

Pete37

Pete37 said:

But that costs about $1500 for the new fridge

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Come on, they arent that much in Australia and this is pretty close to being the most expensive country on the planet

plus another $500 for removal of the old unit and installation of the new.

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Pulls out plug, plugs back in? Or maybe you have it built in with fancy timber-work surrounds?
Mine certainly wont be - easy change out.

But the only semi-flat horizontal surface I have for the array is the top of the lower salon

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Looks at roof of flybridge

How the hell do you get a 1,250 lb battery out of the boat? I'm assuming it comes out in pieces.

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Like most if not all battery banks.

IF you are on a budget the best solution might be the old sail cruisers solution.

Build a BIG well insulated ( 6 inches of the best) top opening fridge freezer and install an engine driven compressor with huge eutetic plates.These are just a welded tank with brine inside .

Assuming you move every second or 3rd day no noisemaker or anything else will be required.

Used to be very common for distance cruisers that required independance.

FF said:

IF you are on a budget the best solution might be the old sail cruisers solution.

Build a BIG well insulated ( 6 inches of the best) top opening fridge freezer and install an engine driven compressor with huge eutetic plates.These are just a welded tank with brine inside .

Click to expand...

Read the bit I posted earlier about marine refrigeration causing problems and not wanting a built in unit for ease of swapover.
I have seen many many many eutectic systems binned over the years due to failure and I have been to many BBQ's where we have feasted on a eutectic owners rapidly defrosting supplies.

IF you are on a budget

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I am not on a budget, but I do want value for money.
$25 to $30,000 for 300 litres of refrigeration and a generator does not look like value for money when compared to a 3rd of that for an efficient 240volt fridge ,solar and battery bank

Pete,

I'm not sure why you take my posts as suggestions for you. All my comments are directed to Parmenter who has expressed an interest in avoiding installation of a generator. In other words, he is looking for an alternative solution to keeping the fridge cold. The fridge is typically the largest continual draw on a boat's electrical resources (short of air conditioning, which almost demands a generator away from the dock - almost...).

I'm sure you have no intention of spending thousands of dollars to rework a system on your boat that works perfectly. I wouldn't either. But, I feel much of what you have suggested is a bit off the mark - and a bit disrespectful?

Building a Lithium battery is no more a "hobby" than installing a diesel generator could be called a hobby. It is a part of boating (which actually IS a "hobby") and every bit as productive and viable as navigating, installing a radar, replacing an aging fridge, etc.

Solar plus Lithium does not need to cost more than a diesel generator installation. You do NOT need "unlimited money" any more than you need "unlimited money" to go yachting in the first place. Each of us has a budget and finds a way to get out on the water within that budget.

Here's a quick budget:

1. 1,000 watts solar panel - $1,000.
2. 4,000 AH lithium LiFePo cells - $4,400. (Enough for a 12v/1,000 AH battery)
3. 2,500 W Pure Sine Wave inverter - $1,500.
4. 60 A solar controller/charger $500.
5. Battery Management System $700.
6. Shore power charger $600.
7. Misc bits and pieces $500.

Total $9,200.

This is "real" money, but less than a diesel generator installation. It can be scaled up or down, depending on desired use and budget. Battery weight about 315# (could be made of 4 each 1,000 AH cells or multiples of smaller cells). My battery is 16 each, 1,000 AH cells, each weighing less than 80#, not an impossible task to handle. Building a battery is not dissimilar to using 6v golf cart batteries to build a 12v or 24 v battery, something many here do as a matter of course, not as a "hobby."

A 1,000 AH battery will keep a 50w fridge cool for a week or more w/o ANY sun replacing energy into the battery. If one is confident in the amount of sun charging available, then the battery could be sized smaller.

If one already has an inverter/charger that works OK, then one need not replace. LI batteries are very tolerant to charging, needing only on/off. The battery management system can be wired to disconnect the inverter should any cell get of spec and also, disconnect the charger, should any cell get out of spec. If purchasing a new inverter and a new charger, then chose units that can communicate with the BMS (battery management system) and either throttle up/down or turn on/off as necessary.

Pete, I feel the need to reiterate, I am NOT trying to convert you nor give you advice - as an old salt (who prefers Bowditch to "cute" iPhone apps), you have the experience and knowledge to discuss intelligently electrical issues that pertain to daily use, battery size and generator use. Respectfully, without knowing you better, I make the assumption you don't have the same experience with solar and Li-Ion batteries? If so, I stand corrected.

Photos of Sunshine's Battery

Here is a photo of Sunshine's 48v/16 cell/1,000 AH battery - wires lead to the BMS (battery management system). The BMS has a remote panel (photo also attached) that:
1. Turns the battery on/off with a key switch
2. Displays battery status - % of charge - highest and lowest cell charge - highest and lowest cell temp - BMS temp - rate of charge/discharge - total AH - total voltage.
3. Allows for manual on/off of charging devices (solar and shore charger)
4. Allows for manual on/off of loads (inverters and DC/DC power supplies)
5. Automatically turns off charging devices should cell(s) be out of spec
6. Automatically turns off loads should cell(s) be out of spec
7. Automatically turns off battery if after turning off charge and/or load any cell(s) remains out of spec.

The battery is located under the master queen berth. The BMS, at the helm.

For a 1,000 AH/12v battery, only 4 of these cells are used.

There are Li-Ion batteries being marketed ready-to-use, in cases similar in size to GRP 31 or 8D with built-in BMS - essentially as easy to use as a standard AGM battery. They tend to be more costly per AH and less versatile, but a lot less intimidating.

One last thing, if you intend to use the battery a lot, the cost of ownership for lithium is LESS than AGM due to the extreme number of cycles.

Hi Reuben,

I rechecked my price on the side by side refrigerator/freezer. Home Depot has units of about the same size as my old fridge for prices ranging from about $900 to $1850. I picked one with the features my old fridge had and it came out close to $1500.

The cost of removing and replacing the fridge is high because the old fridge has to be disassembled to get it up the 24” wide companionway between the lower and upper salon. Once in the upper salon one of the rear windows has to be knocked out to get the fridge out of the upper salon. Once on the aft deck a fork lift picks it up and places it on the back of a pickup truck. The new fridge must then be partially disassembled, put on the forklift and placed in the upper salon. Then, three men and a boy, carefully maneuver the fridge through the 24” wide companionway into the lower salon and then into the galley where it is reassembled, hooked up (water and electricity) and slid into its niche. Finally damage to the companionway trim is repaired and a new window is installed in the upper salon. I think $500 is a conservative estimate. Yard labor starts at about $80 an hour. Not sure what the fork lift costs.

The flybridge has no roof. That’s a canvas bimini top with a radar arch.

Yes, as I thought, the battery bank comes out in pieces. But even in pieces there isn’t room for a 1200 lb. battery in my bilge. I can barely get the four 8Ds (600 lbs.) I am presently using in. To be fair, however, I’m not sure (based on your pictures) how big the Lithium battery bank is. If it is smaller than the current 4 8Ds I could trash them when they go bad and replace them with lithium batteries. But that probably won’t happen for at least 5 years. And also the lithium batteries hey would have to be somewhere near the same cost as my present batteries(about $0.80 per AH).

Building a Lithium battery is a hobby only because I have no use for one. If you need one it’s not a hobby. However, you are correct when you say I have no experience in Lithium batteries. But I do have some experience in designing solar arrays for satellites.

BTW, small diesel gennies start at about $4,000. With installation figure $5,000. That’s a lot less than $9,200.

Hi FF,
As I said to Reuben, my Connie’s bilge is already chock full of permanently installed stuff (like 7,000 lbs. of engines, 1000 lbs. of generator, 600 lbs. of batteries, battery chargers, 200 gallons of fuel tanks, etc., etc., etc.) There’s no room for anything new that’s described as “BIG”. However, I am interested in a refrigeration system using eutectic plates but I’m not sure where I could put it.

Hi All,
Many of you must have very poorly installed generators because you refer to them as noisemakers. My noisemaker (genny) is in a hush cover and the hush cover is installed in a sound insulated generator room. About all you can hear is the slight noise of water gushing out of the exhaust pipe.
Pete37

Hi Reuben,

I'm interested in the eutectic plate refrigeration system because it seems more efficient than an ordinary refrigerator. Do you have any reference on their construction and does anyone make an "off the shelf" model?

Pete37

Hi All,

I stumbled upon an old post by Klaus (Tinker/Guru) posted on 21 Jan 2013 talking about solar powered eutectic refrigerators. He has one on his sailboat. He references a company in Australia named "Autofridge" that makes them.
He says they work but only to a limited degree. Go to www.autofridge.com.au for further info.

Pete37

Reuben: Assuming that one or more cells might fall out of spec before others do, or perhaps there may be a defect of some kind causing the cell to loose its potential, what does/can the system do to account for it, assuming that each of the cells wired together contribute toward a voltage and amperage expectation programed into the BMS.

Bay Pelican said:

Are the costs that much higher in Australia than North America? At the Annapolis boat show there were several vendors offering diesel generators for $7,000/$8,000 US (6-8kw). Installation couldn't be more than $10,000, likely less.

Marty

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The quotes I was getting in a few months back were $15,000 for 8kva PLUS fitting PLUS daily fuel usage.
That was a Kubota based model from a smaller local manufacturer who I have used before when buying diesels.
I would hate to think what the price would be if I priced a Cummins/Onan , Westerbeake, Fisher Panda etc

Sure buys a lot of panels.

rjtrane said:

Here's a quick budget:

1. 1,000 watts solar panel - $1,000.
2. 4,000 AH lithium LiFePo cells - $4,400. (Enough for a 12v/1,000 AH battery)
3. 2,500 W Pure Sine Wave inverter - $1,500.
4. 60 A solar controller/charger $500.
5. Battery Management System $700.
6. Shore power charger $600.
7. Misc bits and pieces $500.

Total $9,200.

This is "real" money, but less than a diesel generator installation.

A 1,000 AH battery will keep a 50w fridge cool for a week or more w/o ANY sun replacing energy into the battery. If one is confident in the amount of sun charging available, then the battery could be sized smaller.

Click to expand...

Thank you kindly for that
Unfortunately it'll probably cost me double or more than that in Australlia , I may have to look at buying from the states and freighting it in myself for a massive saving.

Was there a supplier in particular you used that I should contact for pricing?

Is it fair to add genset install costs and not some many piece, difficult to engineer solar system?

Where I come form...the genset would be cheaper if adding in both systems install costs...and if DIY..the typical 5KW genset still comes in below the prices being thrown around.

The absolute cheapest way to keep a boat self sufficient is with around 400 amp hrs of golf cart batteries a decent charger and a 1000 watt ($700) Honda generator.

Jump to $899 for the 2000 watt Honda and it will run most microwaves, single air conditioners, etc..etc..

perfect silence? neither is nature.....

psneeld said:

The absolute cheapest way to keep a boat self sufficient is with around 400 amp hrs of golf cart batteries a decent charger and a 1000 watt ($700) Honda generator. perfect silence? neither is nature.....

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I've got a 4.5 Northern Lights Diesel Genset, two 85 watt solar panels and two 8D wet cells for the house. With a propane fridge, I guess that's about as cheap as you can get for on-the-hook power storage. But my Admiral finds genset vibration obtrusive in an otherwise beautiful anchorage. My problem is that she won't become silent about it till the genset does, and I want her to have her way.

One day she asked me to explain how the solar panel system would work, and I told her about the flow of electrons, and the wiring, then the controller, and the charge to the batteries which powered the various items on the boat. Then she said, explain to me how the generator would do the same thing. So I told her about the fuel and the air and the compression in the cylinders that delivered the power to a crankshaft, all of which was being lubricated by oil under pressure by a pump and then cooled from the sea water that was pulled in by another pump and flowed through a hole in the boat to a strainer and then through a heat exchanger and then the exhaust and back out of the boat and that turns a dynamo that is wound with coils of copper........., and about that time I abandoned the explanation and said, "OK, let's go with the Solar".

psneeld said:

Is it fair to add genset install costs and not some many piece, difficult to engineer solar system?

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Ok, so still $15k plus fuel usage

1000 watt ($700) Honda generator.

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$1350 here

Jump to $899 for the 2000 watt Honda

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$1700 here

And they say this is the lucky country

>I am not on a budget, but I do want value for money.<

Any house fridge with a couple of gal of water in the freezer and a 2KW Honda gas noisemaker will be the easiest .

After 2000 hours , but a new Honda.

Although the RV propane fridge would still be first choice with gas consumption of 20# a month , even if propane refill is $100 in Aus it would be most reliable and by far the easiest to live with.

Parmenter said:

Ok, so still $15k plus fuel usage

$1350 here

$1700 here

And they say this is the lucky country

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OK...now list the costs of a 1000 watt solar array down to the last bits of wiring, wire run mounting clips and screws...etc...etc..

In down under prices. I think opinion is driving prices and not reality in this discussion.

And I have no horse in the game...I don't care how my batts get topped off.

Pete - in the space now occupied by your 4 each 8Ds you could fit 8 each 1,000 AH LI cells for a total of 2,000 AH at 12v - at today's prices, the cells would cost about $8,800. Check Balqon Electric Vehicle Manufacturer for more info (sizes, prices, etc.). This is more than 2x the capacity of your current 8Ds.

Regarding plate refrigeration - I have no knowledge of "household" type unit using this technology - only custom boxes (way more expensive than store-bought fridges). I do, however, have experience using holdover plates - I had a 40' Penbo trawler with a 4-53 DD with a clutched compressor belted to the engine. The clutch had an on/off switch. The plate was mounted in a top-loading freezer with holes near the top opening into the refrigerator portion - the hole opening was controlled by a sliding piece of lucite. There was a temp gauge in the freezer. Also, in parallel, a 110v compressor. To control the temperature, the user (me) had to monitor the temp and turn the compressor on/off as needed. It worked fine, requiring about 1 hour/day. I would never want to go back to this technology!

Regarding your old fridge - have you thought of using a chain saw to disassemble rather than tearing your boat apart?

Regarding your Bimini top on the bridge - Solbian makes lightweight, flexible (within reason) panels using Sun Power cells (the best) that can be mounted on top of your Bimini. See: Bruce Schwab - Marine Energy Storage, Solar Power, and Management

Parmenter - not sure why you feel pricing is higher in Australia? You can buy a state of the art Mitsubishi fridge for about AUD 1,000 (Mitsubishi MRC375CSTA Refrigerator | Compare Prices & Save shopping in Australia). This is the type of fridge we have been using for years - very efficient - and high end interiors. Lots to choose from.

Ditto solar controllers - one of the ones I am considering for our next project is made in Australia by Aerl ( http://solarmagazine.com.au/news/solar_battery_charging_with_the_coolmax_sr_maximizer/080286/) - about AUD800. I like this unit since it has CANBus communication and can interface with the battery management system.

Winston batteries are in stock in Australia at close to the USA price - see: EV Works Pty Ltd - About AUD1,100/1,000AH cell.

Solar panels are exactly the same price as in the USA (most are mfg in Asia) - see: Solar Panels - Solar Cell Modules - Solar Power Panel Price & Specifications - Solar Online Australia

These are only starting points that I quickly found using Google here in the U.S. - I'm sure you can find more.

Healhustler - In my battery of 48v, I have 16 cells at nominal 3.2v each for 51.2 v total. If a single cell were to fail, I could remove from the string, bringing my voltage down to a nominal 48v - still OK. If you have a string of 4 cells for 12v, then you'll need to replace the faulty cell unless your battery is made of of smaller cells (i.e. 200 ah each) wired in both series AND parallel. In that case, you can remove the faulty cell keeping voltage constant - replace the cell ASAP to assure even charging. Some of what I am saying may depend on the BMS you have installed and if it can easily handle changes like this on the fly. If not, then shut off the battery, replace the cell, and resume operation. The LiFePo chemistry is quite stable - the chances of a cell going out of spec is minimal. Some operators do NOT even use a BMS with these cells (I'm not recommending this).

Hope this answers some questions?

Right now I'm busy installing an HRO Safari 170 Gal/Day watermaker on Sunshine - once done, she will be truly independent.

Responding to questions/comments

Pete - in the space now occupied by your 4 each 8Ds you could fit 8 each 1,000 AH LI cells for a total of 2,000 AH at 12v - at today's prices, the cells would cost about $8,800. Check Balqon Electric Vehicle Manufacturer for more info (sizes, prices, etc.). This is more than 2x the capacity of your current 8Ds.

Regarding plate refrigeration - I have no knowledge of "household" type unit using this technology - only custom boxes (way more expensive than store-bought fridges). I do, however, have experience using holdover plates - I had a 40' Penbo trawler with a 4-53 DD with a clutched compressor belted to the engine. The clutch had an on/off switch. The plate was mounted in a top-loading freezer with holes near the top opening into the refrigerator portion - the hole opening was controlled by a sliding piece of lucite. There was a temp gauge in the freezer. Also, in parallel, a 110v compressor. To control the temperature, the user (me) had to monitor the temp and turn the compressor on/off as needed. It worked fine, requiring about 1 hour/day. I would never want to go back to this technology!

Regarding your old fridge - have you thought of using a chain saw to disassemble rather than tearing your boat apart?

Regarding your Bimini top on the bridge - Solbian makes lightweight, flexible (within reason) panels using Sun Power cells (the best) that can be mounted on top of your Bimini. See: Bruce Schwab - Marine Energy Storage, Solar Power, and Management

Parmenter - not sure why you feel pricing is higher in Australia? You can buy a state of the art Mitsubishi fridge for about AUD 1,000 (Mitsubishi MRC375CSTA Refrigerator | Compare Prices & Save shopping in Australia). This is the type of fridge we have been using for years - very efficient - and high end interiors. Lots to choose from.

Ditto solar controllers - one of the ones I am considering for our next project is made in Australia by Aerl ( Solar battery charging with the COOLMAX SR MAXIMIZER — Solar Australia — The magazine for Australia's solar energy industry) - about AUD800. I like this unit since it has CANBus communication and can interface with the battery management system.

Winston batteries are in stock in Australia at close to the USA price - see: EV Works Pty Ltd - About AUD1,100/1,000AH cell.

Solar panels are exactly the same price as in the USA (most are mfg in Asia) - see: Solar Panels - Solar Cell Modules - Solar Power Panel Price & Specifications - Solar Online Australia

These are only starting points that I quickly found using Google here in the U.S. - I'm sure you can find more.

Healhustler - In my battery of 48v, I have 16 cells at nominal 3.2v each for 51.2 v total. If a single cell were to fail, I could remove from the string, bringing my voltage down to a nominal 48v - still OK. If you have a string of 4 cells for 12v, then you'll need to replace the faulty cell unless your battery is made of of smaller cells (i.e. 200 ah each) wired in both series AND parallel. In that case, you can remove the faulty cell keeping voltage constant - replace the cell ASAP to assure even charging. Some of what I am saying may depend on the BMS you have installed and if it can easily handle changes like this on the fly. If not, then shut off the battery, replace the cell, and resume operation. The LiFePo chemistry is quite stable - the chances of a cell going out of spec is minimal. Some operators do NOT even use a BMS with these cells (I'm not recommending this).

Hope this answers some questions?

Right now I'm busy installing an HRO Safari 170 Gal/Day watermaker on Sunshine - once done, she will be truly independent. Any suggestions?

Pete37 said:

Hi Reuben,

I'm interested in the eutectic plate refrigeration system because it seems more efficient than an ordinary refrigerator. Do you have any reference on their construction and does anyone make an "off the shelf" model?

Pete37

Click to expand...

Pete: We had a DC5000 cold plate/ system made by Sea Frost, which they still make and is expensive. The system was on a thermostat but the 1/2 hp DC motor drew 35 plus amps when it was running and was noisy. DC5000 Pricing The system worked well for us and at the time, with 75-85 degree F water, the compressor would only run 2-3 hours per day.

Nigal Calder had been an advocate of cold plate systems for years. In his 3rd edition, he talks about the efficiencies of the Danfoss compressors such as the DD35 and BD50 compressors and compares them to the cold plate systems. At 4 times the cost of the new compressors with their efficiencies, it's pretty hard to justify the cost. A refrigeration compressor system that includes the evaporators that will cool to a 14 cubic foot box can be had for ~$1,200 US.

Nigel Calders book, Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems has a good discussion. Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems: Nigel Calder: 9780071432382: Amazon.com: Books

Also look at RParts; RParts - www.rparts.com

and Kollman Marine's web site: Kollmann Marine