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Discussion Starter · #1 ·
I've decided to get rid of my propane fridge and put in an Engel dop-in 12v model:

https://www.engel-usa.com/products/...n-models/engel-mb40-drop-in-remote-compressor

I believe it will use between 24 and 50 amps per day, depending on the ambient temperature and whether I run it as a fridge or freezer. I currently generate all my energy needs with two 45w panels and store it in one big 160a battery (I have a 70a cranking battery as well). I realize I'll have to upgrade my energy system with the new fridge. I can fit one big 240w panel over my bimini (fixed between the hard dodger and the arch) or two 100w panels. The price per watt is much cheaper with the big 240w panel. I would also upgrade my battery bank to one 220a battery. MMy energy use is low (all LED, tiller pilot on windvane, manual everything) so I should have a daily energy requirement of about 50 or 60 amps tops. I like keeping things simple. My questions are:

Will I have enough solar panels (total 330w) to reliably meet my energy needs?

Is there any disadvantage to using one big solar panel instead of two smaller ones?

Will my house battery bank of one 220a deep-cycle battery be enough? Batteries are expensive here and, unfortunately, we can't get the 6v golf cart batteries that are so popular in the US.

If anyone has any suggestions or advice, I'd be grateful. I suppose I will also upgrade to a better solar controller as well. Thanks in advance!
 

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Discussion Starter · #13 ·
I've seen suggestions to use two panels, each with its own controller, so that you'll get maximum output of any panel that isn't shaded, as opposed to a compromised output if a large panel is even partially shaded from time to time. That made sense to me.

Unless sunshine is guaranteed, a 220AH bank is pretty marginal to be running a fridge or esp. a freezer even though I believe the newer models are much more efficient than our old Adler Barbour which uses over 5 amps running (usually at a 50% duty cycle)

We currently are running a single 100W panel, a 440AH bank and have upgraded our alternator to 90A capability with a 'smart regulator' and unlike past seasons this summer we did not need to plug in anywhere. Very pleased with this setup.. the solar (in sunny conditions) gets about 10-15AH ahead of the fridge during daylight, cutting our daily draw by more than half. We do get 12-14 hours of sun in our summer months so that helps a bit too....
Thanks for the advice Ron! I agree that 220a is a bit small for a service battery bank, but the options here are limited. As it is, this battery costs about USD$500 in Brazil!! I'm going to think about using 2 panels over the bimini, each on their own controller, but it will double my cost for sure. Perhaps I'll leave my existing two 45w panels on their own controller and run the new one(s) on a better MPPT controller.
 

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Discussion Starter · #15 ·
The OP is getting a 220 amp hour battery which can supply the night half of the 50 amps per 24 hours.

With 330 watts of solar he has more than enough to run the freezer all day and still charge up the 220 amp hour batt.

Theres no use going crazy about it apart from connections the whloe solar instalation is maintenance free. Stick them in any manner he likes that gets sun for his area.

In the trade wind areas with my configuration I found that the early mornings the big problem. So I got a small 70 watt panel and prop it up on deck against the base of the mast at 45 degrees. It grabs the sun from sun-up because the wind is always east... or NE or SE.
That's what I've been thinking too. I can run the fridge off the solar panels during the day while charging the battery and then lower the temperature setting at night if necessary. I also cruise in an area of very light winds and end up motoring more than I'd like to admit. One of the advantages of the Engel fridge is you can use it as a fridge or freezer. When motoring you can set it to freeze and then turn it off at night. I would like to keep things as simple as possible, hence the idea of one big panel, one controller and one battery.
 

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Discussion Starter · #17 ·
with 2 you have redundancy and a backup in case of physical damage to one or the other and all you would need to do to stay alive is to reduce consumption.

most budget cruisers use 1, or a big one and a small very small one wherever space may dictate.

2 seems to be the way to go for most.

since im not currently cruising I only have a maintainer panel and single battey bank at 100amps, altough bigger than needed for that around 85watts back on the davits....

a second one would be the way to go if I added a small drop in cooler or other gear

good decision on the engel drop in!

jealous
Fala Christian! With the big 240w panel I'd have a total of 3 panels (the two existing 45w panels and the new one). I agree that the big panel is a bit like putting all one's eggs in one basket... The problem here (as you well know!) is that we don't have all the (cheap) options and products available in the US and Europe. We have to work with what's available. As it is, I'm going to pick up the fridge in Canada and fly it back as a piece of luggage! Sadly, I can't bring the panels as well on the plane...
 

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Discussion Starter · #23 · (Edited)
I don't think Renogy is in the same class as Kyocera. From the Renogy Warranty download:

http://renogy.com/wp-content/uploads/2014/04/Warranty-off-grid-kits.pdf

"LIMITED WARRATNY: Renogy warrants this product will be free from defects in
...
The warranty does not cover failures result from ...natural elements, ..."

Yes, we all make typos (Warratny ?!) but a real grown-up business sends that stuff past legal and engineering and other people and multiple eyes have to fail to read it. Typos on an important legal document like the warranty mean it isn't a very established business "yet".

The warranty also excludes damage due to natural elements, which would mean rain and salt water spray. So, there's no warranty for exterior or shipboard use. That's even better than the companies that exclude "use on moving vehicles" and boats.

Coming back to the numbers...

"I believe it will use between 24 and 50 amps per day, "
Let's say that's 50, and it would be 50 Amp-hours not amps. It would be important to know if that's at 12.6 volts (battery power) or 14.4 volts (alternator power) since the overall wattage pulled will be different. Split the difference and let's say 50 AH at 12.6 volts for a nearly full battery...

"...one big 160a battery ...I would also upgrade my battery bank to one 220a battery."

" I should have a daily energy requirement of about 50 or 60 amps tops." 10AH for everything else seems conservative, but if you have LED nav and cabin lights, or no night lights, it might be.

"Will I have enough solar panels (total 330w) to reliably meet my energy needs? "
If you are using an MPPT controller, you will get about 15% more power out of the panels than any other kind of controller. That is, an MPPT controller will give you almost the full rated power at battery voltage (330W at 12.8 volts, about 25 Amps) and depending on installation angle, time of the year, how far off the equator you are, you can count on that for the equivalent of about 5 hours per sunny day. So, about 125 Amp-hours per day from the solar panel. Without the MPPT controller, possibly 15-20% less power because other controllers throw out the excess voltage from a solar panel, which might be 17-22 volts for a nominal "12" volt system. Even if you didn't use MPPT you'd probably see 100Ah per day, which would be "enough" but give you less of a safety margin.

If you're making 125 Amp-hours and consuming 60Ah, you'll have plenty of power. I'd even suggest keeping the 160Ah battery as long as it is in good condition, and not replacing it until it weakens or there's some other good reason.

Assuming, of course, I've gotten my math right, which doesn't always happen.
Thanks for the advice Hello. I've heard good things about the Renogy flexible panels so far, but your observations about the warranty are noted! And that typo is inexcusable. I think the fridge will consume less than the 50 amps I stated. That was the worst-case scenario- 45 degrees in the cabin and running it on the coldest freeze setting. I don't recall it ever being that hot in the cabin! (and I have the option of turning it down at night). The rest of my energy consumption is really very low- all LED cabin and nav lights, no pressure water, no gas solenoid or pumps beside the bilge pump, manual windlass, modern energy-efficient electronics etc. I really should work out the amp consumption to be certain, but I think about 10 amps sounds about right (if I don't use the tiller pilot on the windvane). I will take your advice on keeping the 160a battery to see if it can keep up with everything. It's not new, but seems fine. If I could buy the 6v batteries here, I'd get a bigger bank for sure. Cheers!
 

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Discussion Starter · #28 ·
Denise, do you have one of these Engel fridges? I'd love to hear about daily amp draw and if they make any noise when running. My current propane fridge is silent- something I've come to take for granted. :)
 

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Discussion Starter · #34 ·
Another thing I'm seeing is that the big 240w panels put out around 30 volts. From what I have read, I would need a better quality MPPT controller to take advantage of the high voltage. Perhaps the best solution after all is two 100w panels on cheaper controllers.
 

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Discussion Starter · #36 · (Edited)
Auspicious, I intend to upgrade my battery bank in the future when I can get hold of some decent batteries. Ideally I'd have about 400ah and my 70a starter battery. The problem here is I can't get 6v golf cart batteries, only those sealed 12v deep-cycle ones (and if you saw the price, you'd have a heart attack!!). I don't like them because you can't get at the cells to top up the water. I can get those fancy Optima (AGM?) batteries here, but I'd have to sell one of my children first :). Again, if anyone wants a free sailing holiday in Brazil and can fly down with panels or batteries, just let me know!

If I go with the two 100w panels is it worth it put each one on its own PWM controller? I can get cheap 10a or 20a PWM controllers here (made in China). Both panels would be oriented the same way, but I suppose there would be moments when the mast or rigging could cast a shadow over one panel and not the other. If there is a big gain, I'd go with two controllers, otherwise I prefer to keep things as simple as possible. Sorry to ask so many questions, but I'm as thick as a whale omelet when it comes to things electrical....
 

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Discussion Starter · #41 ·
I was just down at the boat over the weekend to take some measurements and it seems I can fit two 140w panels over the bimini. I'm wondering if a 10a controler is enough for each panel, or should I go with a 20a. I don't want to spend too much on the controllers as I intend to replace them with better quality MPPT controllers when I have the chance to buy them abroad.
 

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Discussion Starter · #42 ·
Just a quick update! I'm getting ready to fly to Montreal for xmas and to pick up my Engel drop-in fridge. I still haven't decided on which solar panels to go with. I have found some cheaper 150w panels in Brazil and I can fit two of them over the bimini, each on a (Chinese) MPT 20amp controler. The other option I'm toying with is getting one big 240w (but 30 volt) panel and buying a better quality MPPT controler for it while I'm in Canada. I'm still confused about which setup will give me the most energy return (the monetary cost being about the same). Any ideas?

If I go with the MPPT controller (30a?), does anyone know a good source in Canada to buy one? Ideally I'd like something simple and reliable. Any suggestions for brands and models?
 

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Discussion Starter · #46 ·
Mbianka, I can't find the Renogy panels here in Brazil, but if I could they would be my first choice. Any idea how many amps per day your Engel fridges use? Which models do you have?
 

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Discussion Starter · #49 · (Edited)
Thanks Mbianka. I've just bought the Engel MB40 and I hope to see the same results when I get my new panels installed. My current setup (2 x 45w) covers my current needs, but the new fridge will need extra juice- hence the two 150w panels I will install.
 

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Discussion Starter · #52 · (Edited)
Brian.. is that net amps, or 'when running'? What's the typical duty cycle? Good numbers compared to our old AB unit.
Ron, the Engel fridges have a loyal following who rave about their low power consumption and reliability. That's why I ended up buying one and not building a box and installing a cooling unit. They are not huge fridges though.... The one I am insalling is a bit bigger than my current propane one, but it's big enough for my needs. The cool thing about the Engel is that it can run as either a fridge or a freezer (but not both at the same time).

Here is the engel chart with power consumption:
 

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Discussion Starter · #59 ·
OK so it appears that at an ambient temp of 25 c and using as a refer unit we would use approx 40ah per day for the 42 qt unit
Newhaul, If I'm reading the chart correctly, in a 30c environment and running the fridge as a reefer (setting 1, just above freezing) it uses 1 amp/hour and runs 34% of the time. Wouldn't that be 8.16ah per day? Of course that's assuming no one opens the fridge or puts in any warm stuff!

On the topic of adding insulation- I ended up buying the drop-in unit with the attached compressor (it is attached to the bottom of the box). I'll have lots of dead space around the unit when I install it. Any ideas on how to improve the insulation (without "insulating" the compressor and retaining the heat)? Also, wouldn't adding foam around it create an environment for condensation and risk damaging the unit from corrosion?
 

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Discussion Starter · #78 ·
I thought I'd post a short update on my new fridge and energy consumption. I installed the new Engel fridge, but haven't yet installed the new solar panels and battery. I'm still using the two 45w panels and cheap controller charging my 160a house battery (for the time being!). After 5 days on the boat I have found that the panels and battery seem to be powering the fridge fine. I have 12.8v at sunset and wake up to 12.4v or 12.5v in the morning. Our autumn sun is still fairly high and the panels are putting out juice OK. When winter arrives they won't be so efficient. In conclusion, I think my original plan to add two 140w panels and a 220a battery will work out very well. I'll keep the 160a battery for a starter/reserve battery.
As for the Engel fridge, all I can say is it is FANTASTIC! Very low power consumption (it sips juice), doesn't frost up like the old one and things are very cold on the lowest setting. It is absolutely silent when running and is very well made. No relation with the company, just a very satisfied customer.
 
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