Newbie - Small System in Paradise

Mex Bob

Gentleman:

I am looking for some advise on building a small solar system for my home in paradise. I do have very small needs, and live a very simple lifestyle. I require no heating or airconditioning year round. No water pumps or electric cooking. Most of the cooking is very small appliances, and all are LP gas-powered. My electric needs are the smallest I have ever had in my life, my current electric bill is less then $10.00 every 2 months (thats right, every 2 months!).

Presently, I only have a 5 cu. ft. ref/freezer, 1000W microware, 1200W toaster oven, CF lights, and a laptop computer. I only have 4 lights, all are CF's and will be changed in the near future to LED's. All of my internet service comes from a neighbor, so no usage for that. No TV, Stereo, or entertainment equipment. No printers or copy machines. I do have one 16" 110V fan, that is rarely used, and then only for about 2 or 3 months out of the year.

I guess I should describe my idea of paradise, I currently live in central Mexico; and have lived here for almost 14 years. The area is high desert, about 6,500 foot elevation, humidity mostly is between 20 to 30%, and our rain is limited to about 7 inches a year. Most of that rain comes in June and July. The average temperature is 72 degrees yearound, our hottest month is May with temps in the 90's at times. I think I can count on two hands the number of times we have broken 100. On the low side of the temperature, maybe once or twice it has gone below 32 degrees, and then mostly in the higher elevation in the area. When it hits 60 degrees here, people bring out the winter coats. From what I can tell from the solar maps I have seen online, we would be at least 5+ hours of sun daily all year. If someone can suggest a better map then I have found, I would appeciate it. I suspect our sun hours will be much higher then I have found. The nearest major city is Celeya.

My plans for the future are, and I hope this will give a good idea of my power needs. I will be adding a 7 cu. ft 110V chest freezer, the only rating I have for it is the yellow tag, and it says 278 Kwh per year. I have thought about using a timer, based on some others peoples suggestions, one hour on, two hours off. I don't have a Kill-a-Wat, and will have to wait for my next trip to Texas. BTW, I have seen them on the Hope Depot website for about 20 bucks. My microwave now only gets about 10 minutes a day usage, and the toaster over about the same. I do have a very large blender, and a crockpot which I might like to use a bit more. The blender is a Vita-Mix, it is very LARGE, the back plate says 10.5 Amps. I can't imagine using it more then about 3 to 4 minutes a day average. I will have only 3 or 4 lights, and by the time the system is in, they will be LEDs. It is very rare that more then one light at a time would be on. My laptop is 19 volts in, and a did find on this forum a link to a company that will provide a mini-transformer that will stepdown 24V to 19V. Not sure that this is even worth counting if it goes direct from the batteries???

The most important item for me is the cost, I am a disabled vet, and it doesn't provide much in extra funds. As I mentioned, I am looking at about 6 months to complete the system. I would like to increase the capability of my system over the next few years, so I think that a 24V battery bank make the most sense. My budget to start is only about $1,500, I know that will limit me severely!

I have found some 285 Watt panels, that cost $.63 per watt. Yes, they are made in China. They have 36.08 Vmp and and a 45.41 Voc. I have thought about buying extra, given the price and future expansion. I have resigned myself to the fact the I will have to start with Golf Cart batteries, and mostly likely get them from Sam's Club (6 volts, about $80 apiece for 207 Ah). CC, I have no clue, but would like get something that will allow future expansion. Again, any ideas or thoughts would be appreciated.

The run from my panels to the CC would be less then 25 feet, and the CC, Inverter, and batteries would be colocated. I am interested in any thoughts on Inverter size and purchase recommedations.

I very much appreciated your time, and look forward to hearing from some of you. I have been following the solar power industry for a long time, and do recall when panels were very small, and the prices ran in the 8 to 10 dollars a watt range.

Many Thanks

Bob

Cariboocoot

Re: Newbie - Small System in Paradise

Welcome to the forum Bob.

Okay, the big question is: where does your electricity come from now, and how much are you paying for it?

You see, off grid power comes with a pretty big per kW hour price. The chances are slim that going off grid will actually save you money. If the utility power is unreliable it may be different. But you're quite right that $1,500 isn't going to buy you much power. I'm not sure this is a sensible move to make.

Mex Bob

Re: Newbie - Small System in Paradise

Thank for the welcome!

Power now comes from the local utility, and your right the cost is very low. Bi-Monthly cost is 100 pesos, which is less then $10. We do have some power problems here at times, but I have a bigger concern about the grid failure. Ok, I'm one of those guys that think it might be possible. I've more or less decided it is woth the time and trouble to do it, and now I'm looking for a way to save as much as possible.

I'm not sure what the per Kwh cost is but I can find out tomorrow.

Bo

Cariboocoot

Re: Newbie - Small System in Paradise

For what it's worth, I believe our resident "champion low-cost off-gridder" manages to produce power at a rate of $0.26 per kW hour. This is due at least in part to some great bargains he's managed to find in equipment. Otherwise the cost tends to be more like three or four times that.

Just as an example, those two golf cart batteries you cite store about 1kW hour AC worth of power. Icarus manages on an amazingly low 400 Watt hours per day, but that includes propane refrigeration. My cabin uses 2.4 to 3.0 kW hours per day with electric refrigeration and that is more along the lines of what most people would use even with minimalist usage.

westbranch

Re: Newbie - Small System in Paradise

Mex Bob, is the grid unstable or just unreliable?
One option is for a battery bank and an AC charger and an inverter. Depending on the loads needed to be supplied, this would be a minimalist system... having solar panels will also add a CC and if needed a battery monitor as well as the extra wiring etc.

Mex Bob

Re: Newbie - Small System in Paradise

Westbranch:

I would say that both describe the problems here, I have been offline for almost 24 hours now, because of a power failure. I do much prefer a complete stand alone system. I have been looking for reccomendations based on the information I gave in my initial message.

Bob

westbranch

Re: Newbie - Small System in Paradise

OK that explains a lot to us. will have to think about it some more.

NorthGuy

Re: Newbie - Small System in Paradise

Bob,

First, you need to calculate the exact power consumption. You can start from your electric bill. It should list the number of kWh you use every month. Look at the bills for last year and find the worst month where your consumption was the highest. This will be a good number for you to start sizing the system.

Mex Bob

Re: Newbie - Small System in Paradise

NorthGuy wrote: »

Bob,

First, you need to calculate the exact power consumption. You can start from your electric bill. It should list the number of kWh you use every month. Look at the bills for last year and find the worst month where your consumption was the highest. This will be a good number for you to start sizing the system.

North Guy:

I have run the numbers in an Excel spreadsheet. I have come up with 1.86 Kwh per day, 2.325 Kwh with inverter loss. Maximum load to the inverter would be 860 watts. The battery bank at 24V comes up to 484 AH. Panel wattage with a PWM CC comes up to 930, and with a MPPT CC is 697.5. This includes both Fridge and freezer, but I expect I make dump the fridge in the near future.

I have 3 other items that I use at times, and have not been added into the numbers. The first is a blender, it is a HUGE Vita-Mix, it is listed a 10.5 Amps (don't know how to do the conversions) At the most it would be used 5 minutes a day. Second item is just a plain old crock-pot, don't have it here now (loaned to a friend), it might get used once a week. I can always use a slow pot on the propane also. Third is a 16 fan 110V, it only gets used on the really hot nights in the summer. I would guess the 3 months of summer, it might get used one night a week for about 3 hours.

The maximum Amps to the inverter at 24V would 35.8

The only CC I have considered is the Morning Star small MPPT unit, or the Rogue MPPT.

I mentioned, I am looking at the JA-285 Panels, all the numbers should be above, I thought about ordering 4, but starting only using two. I can purchase them for $.63 per watt.

I have no idea about what would be a good inverter, one that might allow me some expansion.

I also have found a 24V to 19V for my laptop, only in the $20 range. THe computer is included in the above numbers.

At the beginning, I would have to start with GC2 bateries, I found new 6V 207 Ah for about $80.00 each. I would wire these for 24V.

North Guy, any ideas, suggestions, or reccommendations you might have I would greatly appreciate.

Thank You, for your response.

Bob



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westbranch

Re: Newbie - Small System in Paradise

Mex Bob, are you sure you do not have the output for the PWM and MPPT CC's crossed? Logic c says they should be other way round.

watch the distance from batteries to 24 > 17 v transformer to minimize line losses.
Inverters, Look for Cotek/Samlex brand they have lots of models. Mid price range .

NorthGuy

Re: Newbie - Small System in Paradise

Mex Bob wrote: »

North Guy, any ideas, suggestions, or reccommendations you might have I would greatly appreciate.

I'm not an expert, Bob. I'm a guy like you - moving from grid to off-grid. I'm further along than you are and my system is already functional. I'm not swithed off the grid yet, but I'm now ready to do it at any moment. I used Excel spreadsheet day-to-day usage model to size my system.

My loads are 6 times yours. Relative to the loads I have approximately the same quantity of panels and same size of battery bank that you're going to have. Except for the mid-winter (which you probably do not have), it mostly works fine, but there are two points:

First, my batteries are very havy ones, so I can discharge them to 20% SOC without problems. I haven't used this yet, except for testing, but I can if I need to. You probably cannot do that with GC batteries.

Second, I rely heavily on generator. If there was a dark day, I need to run a generator right after sunset. That's fine with me. But with the battery bank sized as yours, you will need to do that too.

I cannot recommend any particular model of inverter, but I'm sure there are many people here who can make suggestions.

For the charger, I would certainly go with MPPT, which will give you a flexibilty to expand.

Sun Dog

Re: Newbie - Small System in Paradise

If you use the 2.325kWH/day as your max load your numbers and material list may look something like this:

2325 watts x 2 days autonomy = 4650 watts

not taking your batteries below 50% means 4650/ .50 = 9300 watts/ 24V system = 387.5Ah battery bank

10% charge rate for battery bank = ~40 amps

each 285 watt panel used with a MPPT controller will technically give you 285W/24V = 11.9A so 3 preferably 4 panels

Two strings (8 batteries in total) of the 207Ah batteries
Likely a 2000W or larger inverter or inverter/charger
Four 285 panels
A separate battery charger if you go with an inverter only
A 2000W to 3000W generator
Wiring etc
Charge controller (don't know about the new one, but the previous Rogue has a max of 800W for a 24V system)
The same place you found you panels has the Outback FM60 on for $434

2.325kWh/day is a pretty good load. If you can make some compromises and get that down all of the above gets smaller too. I know they are pricey and I don't know how easy it is for you to get propane but for small systems there is a lot to be said for propane fridges. The whole system gets smaller and you can even turn your inverter off at night or when you aren't there.

Photowhit

Re: Newbie - Small System in Paradise

Hi Bob, several things to consider, likely in the high desert and closer to the equator, you will have sun most days and some charging most days, hence you might be able to live with less storage to get you through those few cloudy days. Though perhaps you often have clouds w/o rain.

I would shoot for 800 watt array minimal to start, I think the Rogue Charge controller tops out around that in a 24 volt system. You might be able to connect 3 of the 285 watt panels and just loose the extra wattage above what the Rogue can use, Marc (the guy who makes those fine charge controllers, could let you know) If you can get these 36 vmp panels delivered at a reasonable cost to you in south Texas, I am a fan of just using a PWM charge controller, Other than a ladybug infestation that shorted one out I've used 2 - 1 is 13 years old and the other is over 20 years old. There is not as much difference between them as you have noted, perhaps 10-15% depending on how close to fully charged your batteries stay.

Before you go very far check out shipping, I suspect I know the (Miami?) company that your considering, I checked out there feight rates for 4 285watt Suntech panels (similar size weight) and to me the shipping was $315, that would add about 30 cents a watt.

I just did a post on Iris Quiet Power inverters that are coming available off military surplus, they might make a good choice, they appear to be Prosine 1800watt inverters (same case and specs) They are a very high quality inverter, though buying used can be tricky. I have been a fan of Prosine, since seeing them on fishing boat in Florida, I understand they have had some issues with the charging models (from listening on the forums) but it's pretty rare to hear of the 'inverter only' models giving early problems.

Since it appear that you have very cheap power now, you might consider piecing together your system, while things are still OK and prepare to go off grid. There is nothing wrong with Sams club or Costco golf cart batteries. Likely the best bang for the buck for small systems, just bought 4 more for my cabin(so I can bring my big battery to the new house)

I think if you hope to expand your system later I would look into a midnite classic charge controller, you appear to have a handle on computers so the 'lite' model that sells for $500 at northern Arizona Wind and Sun (I think that still has free shipping in US?) is the way to go.

Mex Bob

Re: Newbie - Small System in Paradise

NorthGuy wrote: »

I'm not an expert, Bob. I'm a guy like you - moving from grid to off-grid. I'm further along than you are and my system is already functional. I'm not swithed off the grid yet, but I'm now ready to do it at any moment. I used Excel spreadsheet day-to-day usage model to size my system.

My loads are 6 times yours. Relative to the loads I have approximately the same quantity of panels and same size of battery bank that you're going to have. Except for the mid-winter (which you probably do not have), it mostly works fine, but there are two points:

First, my batteries are very havy ones, so I can discharge them to 20% SOC without problems. I haven't used this yet, except for testing, but I can if I need to. You probably cannot do that with GC batteries.

Second, I rely heavily on generator. If there was a dark day, I need to run a generator right after sunset. That's fine with me. But with the battery bank sized as yours, you will need to do that too.

I cannot recommend any particular model of inverter, but I'm sure there are many people here who can make suggestions.

For the charger, I would certainly go with MPPT, which will give you a flexibilty to expand.

North Guy:

I have done some changes to the figures, by dropping the fridge, I can keep it on grid until I am ready to use the freezer and a large EPS cooler, about R30. Ice lasts for about 3 days.

The new numbers are:

Daily Load 1110 W
Daily loadwith inverter loses 1387 W
Battery Bank at 24V 490 AH 20% DOD
Panel Wattage - PWM 555 W
Panel Wattage - MPPT 416 W
Maximum Amps to Inverter 35.8

I was also wondering what effect adding a timer to the freezer, on for one hour, off for 2 hours. Have heard of a number of people doing, checking the results with a KillaWatt.

Sun hours in a town 25 miles south of my location

Jan 4.8

Feb 5.81

Mar 6.73

Apr 6.91

May 6.77

Jun 6.33

Jul 6.11

Aug 5.93

Sep 5.41

Oct 5.24

Nov 5.05

Dec 4.43

Sun is not a problem here, and this is not the best in Mexico.

Your thoughts?

Photowhit

Re: Newbie - Small System in Paradise

Mex Bob wrote: »

Daily Load 1110 W
Daily loadwith inverter loses 1387 W
Battery Bank at 24V 490 AH 20% DOD
Panel Wattage - PWM 555 W
Panel Wattage - MPPT 416 W
Maximum Amps to Inverter 35.8

So Where are your numbers coming from?

So your planning on getting an inverter with a 80% eff?

Your going to have a battery of 490Ah based on 20% of what? daily use? 1387/24=58amps x 5 = 290Amps (20% DOD of daily load though some of that will be during the day.)

I guess you saying an MPPT CC is 25% more effiecent than a PWM, I say don't beleive it, Mostly this would be on cool days while in Bulk only, doubt many days you will see this much better with MPPT CC.

Max amps to inverter? This would be you peak load 35.8amps x 24volts= 860 Watts, not sure where your getting this, your blended will draw more wattage, ???

Mex Bob

Re: Newbie - Small System in Paradise

I got those numbers from an Excel spreadsheet I was given. I have to admit, it is a bit over my head. Looking for answers.

Cariboocoot

Re: Newbie - Small System in Paradise

Mex Bob wrote: »

I got those numbers from an Excel spreadsheet I was given. I have to admit, it is a bit over my head. Looking for answers.

Skip the spreadsheet. Calculated usage numbers are always wrong. The reason being they are based on the information supplied by manufactures: the tag that says "8.5 Amps 115 Volts" and what is usually just a guess at how long the thing is on. When you can't afford wide margins for error, you have got to measure your power consumption with a meter. Things like usage patterns will change the numbers. Refrigeration equipment, for example, will vary in its consumption due to weather and how often you open the door.

As long as we're speculating (guessing) you seem to be after approximately 2kW hours AC per day. Not much different from what I have. You have an advantage in having 4+ hours of good sun year-round.

What a 2kW hour 12 Volt system might look like:
668 Amp hours @ 12 Volts (allows 25% DOD on two days; you could probably cut that in half and gamble on sunlight alone to supply a significant portion of your power).
1044 Watt array (works out for charging the above battery bank and just over 2kW hours a day with the Icarus formula).
80 Amp MPPT controller (MidNite Classic 150 or Outback FM80) or two smaller PWM controllers with possibly a slightly larger array (latter may work out to less money or not; you will have no cold temp advantage there for the MPPT but sometimes the combination of one with "GT" panels works out to a cheaper array).
Pure sine 2kW inverter like a Xantrex Prosine.

You may not need a back-up charge source like a generator, or perhaps just a cheap one.

But in all honesty I don't see getting even the absolute minimal amount of equipment for your $1,500 budget unless you do a lot of shopping around and find some great used bargains. The panels and controller alone would use up all the allotted money.

BB.

Re: Newbie - Small System in Paradise

Mex Bob:

Daily Load 1110 W
Daily load with inverter loses 1387 W
Battery Bank at 24V 490 AH 20% DOD
Panel Wattage - PWM 555 W
Panel Wattage - MPPT 416 W
Maximum Amps to Inverter 35.8

It sounds like you are looking at an 800 watt or so inverter? Depends on what you want to power. A full sized fridge/freezer usually need a ~1,200 to 1,500 watt AC inverter minimum (heavy starting surges from motor, plus defrost heaters if no frost fridge).

The "daily load 1,110 Watts" is probably Watt*Hours (watts is a rate, times time gives you an amount--Like Miles per Hours * Time = Miles driven--it is a very common mistake and I have made that a few times even now when typing up a response).

1,110 WH for a small/efficient home is certainly possible, assuming no refrigerator. A full sized US fridge is going to take around ~1 to 2 kWH per day by itself. A converted chest freezer (running with a refrigerator thermostat) can get as low as 0.25 kWH per day... And 3.3 kWH per day is usually enough to run a "near normal" electrical life with an efficient life style and lots of conservation.

Note that running an inverter 24 hours per day can cost you a fair amount of power in a smaller system... A "smallish" inverter may take 6-20 watts just "turned on" without any loads. So, for example a 10 watt "tare" inverter may use:

• 10 watts * 24 hours per day = 240 watts

That is almost 25% of your daily load--So you should add that to your daily loads.

Anyway--One reason I do not like to use a "spread sheet" to give you the answers--It is only as good as the data entered and you understand the fudge factors used to design the spread sheet. Working with the basics. Say you want 1,350 WH per day (including 10 watt inverter losses) with 4 hours minimum sun (minimum generator use 12 months of year). First, the battery. Assuming 2 days of "no sun" and 50% maximum discharge, using a 24 votl battery bank:

• 1,350 Watt*Hours * 1/0.85 invt eff * 1/24 volt battery bank * 2 days storage * 1/0.50 max discharge = 265 AH @ 24 volt minimum battery

Next, the amount of solar array to run your daily loads:

• 1,350 WH * 1/0.52 typical system efficiency * 1/4 hours of sun = 650 Watt array minimum (for loads)

And we should size the array based on a 5% to 13% rate of charge for the battery bank too (note that a large battery bank pushes up the solar array requirements too--regardless of the loads):

• 265 AH battery bank * 29 volts charging * 1/0.77 panel+controller losses * 0.05 rate of charge = 499 watt array minimum
• 265 AH battery bank * 29 volts charging * 1/0.77 panel+controller losses * 0.10 rate of charge = 998 watt array nominal
• 265 AH battery bank * 29 volts charging * 1/0.77 panel+controller losses * 0.13 rate of charge = 1,249 watt array "maximum cost effective"

So, the "optimum array" would be around 650 watts to 1,249 watts based on my mythical configuration (note, the numbers are not "that accurate"--just keeping the digits so you can repeat my math and follow where they come from).

And lastly, it is always a good idea to have a back up genset / AC battery charger:

• 265 AH * 5% rate of charge = 13.25 Amp minimum
• 265 AH * 10% rate of charge = 26.5 Amp nominal
• 265 AH * 13% rate of charge = 34.45 Amp "healthy maximum"
• 265 AH * 25% rate of charge = 66.25 Amp "pretty big"

And when you power that with a genset... There are a wide variaty of battery chargers. Some are very efficient, some, not so much. A typical 10% rate of charge battery charger loading a genset to 50% of rated VA (volt*amp) capacity would be:

• 26.5 amps * 29 volts charging * 1/0.80 charger eff * 1/0.67 PF * 1/0.50 generator loading = 2,868 VA genset (50% minimum loading)

A very efficient charger may be:

• 26.5 amps * 29 volts charging * 1/0.90 inverter eff * 1/0.95 PF * 1/0.50 generator loading = 1,798 genset (50% minimum loading)

If you are into the generator details, here is one nice thread on trying to find the minimum genset with the maximum efficiency:

Question about battery charger selection with EU2000 generator.

You have lots of sun--But for many folks, they live off the genset for the 3 months of winter--And picking the right charger and genset can save 50% or more on fuel costs.

-Bill

BB.

Re: Newbie - Small System in Paradise

I should add that only in very cold weather (sub freezing) will you see a significant output increase with an MPPT controller (maybe 10-15% increase).

Where MPPT controllers are good is with longer wire runs from the solar array to the controller/battery box. You can run a Vmp-array with higher voltages/lower current and use much less copper wire.

A second "requirement" for an MPPT controller would be with (typically) solar panels >> 100 watts or so... Most of these panels are designed for Grid Tied systems and have "non-standard" Vmp voltages. For a 12 volt battery bank, we use 17.5<Vmp<18.6 volts or so. Most larger (and cheaper per $$$/watt) panels have Vmp in the ~30 to 50 volt range or so--Not usually a good match for charging a 12/24/48 volt battery bank with a PWM charge controller (you save money on the panels and pay the savings on a MPPT charge controller).

For 400 watt or less systems, a PWM controller may make sense. For systems over 800 watts, a MPPT controller is usually the battery choice. Note that most modern MPPT charge controllers have a lot more features (logging, Internet Connections, remote battery temperature sensors, etc.)--So you do get more for your money (if you need any of that).

-Bill

NorthGuy

Re: Newbie - Small System in Paradise

Cariboocoot wrote: »

When you can't afford wide margins for error, you have got to measure your power consumption with a meter. Things like usage patterns will change the numbers. Refrigeration equipment, for example, will vary in its consumption due to weather and how often you open the door.

That is absolutely right. If you do not have Kill-a-Watt, you can use your electric meter. Try living as you would live off grid for a week or two, and record the number on your electric meter every morning and every evening. This way you will know exactly how much you consume. It may be much more or much less than your spreadsheet shows. It's very important to know.

Mex Bob

Re: Newbie - Small System in Paradise

Good Afternoon, Gentlemen:

I want to thank all of you for your time and efforts, it amazes me that such knowledge is available online. My problem is that it is growing much faster then I can afford right now. My initial objective was to be able to provide power for a 7 cu ft chest type freezer at the lowest cost possible. That freezer uses 287 Kwh on an annual basis, or 786 watts per day. Again, this is the yellow sticker that is posted on all appliances. Not sure if its right, and I won't know for at least a week yet. I hope to get a KillAWatt by then. I have posted the sun hours for this area on Post #14

Given that for the next few months, I am limited to about $1,500 and can purchase JAP-285 for $.63 per watt (2 Panels, 570 Watts for $360), 207Ah Batteries for about $90 (4 Batteries for $360), and a C60 CC with Battery Temp Monitor for about $160. The Freezer would be the only 110V item on an as yet to be determined inverter, would I be able to keep the freezer powered. I have had suggestions to use a timer on the freezer on for one hour, and off for two hours. Your thoughts on this? Also adding an inch of ESP (very heavy styrofoam) to the outside of the freezer would very much help keep the power usage down.

The items I mentioned would cost me about $900, leaving the balance for inverter, cabling, and other items. I would limit 12V items to a couple of LED lights, and the converter for my laptop, only computer access, no internet or printer.

Are your opinions that this might be able to work?

Again, all my thanks!!

Bob

Cariboocoot

Re: Newbie - Small System in Paradise

I would watch the freezer and see how often it cycles on/off normally. Then see if insulating the exterior surfaces helps (beware of blocking air flow and coils of course). Switching it on and off externally can be done, but more on a basis of how much interior temperature variation you're willing to accept.

Photowhit

Re: Newbie - Small System in Paradise

Well you understand that freight for 2 panels will likely be the same as for 4 panels? or $300? and that's to a US site.

If it was me, I would look at the total needs for an off grid system, and purchase the batteries now,, I think you'll need the 4 and an Iota battery charger ,and an inverter to fit your needs now and stick with the grid with this as a backup.

Then when I could afford it I'd purchase all the panels you'll need and the charge controller later so you don't end up paying for shipping 2x.

Unless you have a local source for the solar panels at 65 cents a watt, that would be cool!

I would be careful of adding insulation to the sides of freezers as some of them disipate the heat removed with panels near the skin of the freezer, trapping that in would be bad all the way around.

You have excellent sun, and I think 4 golf cart batteries might well be all the storage you need, but I would push the array size up a bit for security. I might even say 3 panels would work for you, but I feel 2 is too marginal, for me at least.

I guess your having things sent to a US address and driving them across? Do you know your shipping costs?