Hello solar guppy, I believe my prospective project location is one of similar geographical and meteorological characteristics.
IT will be just south of cancun Mex. A bit warmer in the winter months but summer months are comparable.

I will have a potential high demand system, that will be off grid, no electrical company hookup anywhere near property.

General house usage should max out around 10kw per day if occupied. Should not be anymore. That is everything except a/c. Problem really hurting the prospective system is my need to have air conditioning. I am looking into the Mitsubishi City Multi system. Seems a fair bit more energy savings then some, but not sure actually performance. I have sized the houses need for air conditioning to just bedrooms. it would be a 5-ton system as which the air condition may average between .35-.5kwh/ton. The city multi scales well, or at least I am told so when only running one bedroom, only running 1ton of cooling. Any way cooling demands can run between 15wkh daily to upwards of 60kwh daily.

Looking at a 6kw solar system. Probably the generic evergreen you mention. This will be a rental property, so there will be weeks with no one in the place, and weeks with only 2-4people. And others with up to 12 people. I am planning on designing system for the load of just 5-6 people. over that I would hope my battery power could sustain me a bit, but also have a 10kw propane generator for high demand weeks. This should keep my system a lot smaller and a lot more economical.
On average about 50 days a year with participation. many of which still have a few hours of sun. But I guess cloudy days can off set them.

Main part of question, am I going to see major losses in solar panel efficiency, how do your panels fair with very strong sunny days. I mean night temps here right now are probably low 80's high 70's then in the early morning already heading toward 90 degrees.
Anything to be really design for or keep an eye on. I plan to mount the panels a little bit off the roof, but Try to keep it not to large of a distance as hurricane winds would have fun if I left too much room.

Also as I am Located Close to Cancun Mexico, actually in Puerto Morelos. I was wondering if you knew of any good solar suppliers other then sunelec (in FL). Probably going be buying most of my stuff from the states. There is a regular cargo ship that travels between here and fort Lauderdale. Figure I can buy most of my stuff have it shipped and still save a ton of money.

Not too many solar companies down here. Visited one today, not sure if was trying to scam me or what but he said average $/watt for a solar panel here is $7/watt. I nearly fell over. That is just cost of panel. I mean wow my system would be incredibly more expensive then the expensive system it will turn out to be.

Also does sunelec do discounts on large orders of say 60ish panels (sun-190) and the hardware to run them? Just figure I ask before contacting sunelec. Figure the sun-190's are a bit better because of the slightly high voltage value. atleast for my location/climate.
Oh if you run the numbers 60x190=11400watts This will be for two houses of very similar demand. 11400/2=5700watts.

Thanks for your time.

The heat will reduce the panel output 5-10% ... in the big picture it's not to bad and there is nothing you can do about it, except account for this in your calculations

On your AC, your numbers are way off, I have a 5 ton unit that cools the whole house here in Florida, so 1 ton a bedroom is nuts. If you haven't built the house yet, make it energy efficient as possble ( insulation )

Rentals are hard because the renters will be clueless to enegry consumption, they will run the AC with the patio doors open!

And 6kw is way to small, I gridtie here in Florida and I have a 12kW system which covers most the energy needs in a enegry efficient home.

The Sun190's ( or 180/170 ) are the best deal anywhere, that part you have right!

The house will be about 3500 square feet and also spread across 3 levels. 5 bedrooms of moderate size.

I do not plan on the 6kw to do all of it, not even close. I just hoping that it would cover a moderate group of people 4-5 maybe 6 people.
It should optimally cover winter months fairly well as little a/c is needed.
Basically the summer months especially with larger groups of guest are an extreme peak in energy I believe is much more economical to run a generator, and not design a system for the extreme. The times of vacancy here is usually summer time, as people prefer to get away to a warm climate in winter time. SO if I did design a lot larger system, I would expect it cover almost everything, but also there would be a fair amount of times it may just sit unused at full battery capacity. I rather start on the small side and maybe add a 1-2kw of solar if needed. I definitely plan on a larger size batter bank(within reason). This way I can upgrade panels if needed, but not run into the problem of adding batteries later. I would love to run the whole house off solar, but financially I believe the 10kw propane generator can save bit of $$$.

As for house it will be all concrete construction but all windows are shaded with about 8 feet of over hanging thatched roof structure. For the lower levels there is very little direct sun light as the upper levels insulate/protect/shade it. AS well as the roof will be shaded by the panels, I would hope provided some cooling effect. Just not sure how the heat radiates off them.

I am also thinking about a Styrofoam block construction, then poured concrete and rebar filling. This will add a lot of insulation. As it is about 2 inches of Styrofoam each side of the wall. Also windows will be not as large as I would design if not dealing with making this place energy efficient.

Something that i am hoping for is guest while on vacation actually do a lot of outdoor things, and really do no hang around in the house. While I may be wrong in the actual behavior. I believe this may help out power usage. I can always buy more panels.
Also things like exterior lighting systems will be on sensor which will not permit the lighting the outside if there is a certain level of out door light. Obviously there can be some level of waste inside, I just have to kind of put things in the house, if abused will not cause a huge hit to the system.
There may be as many as 15 weeks a year without people in the house. These are all almost in either rainy season, or summer. Both poor times for solar to cover the house. All peak rental time will probably have 6 out of 7 day sun. With most actually have all sun.



Also what is your a/c equipment. What are you running, and what is your power consumption and usage. Do you like it??? Any recommendations and product?
I really have no gauge on what the size should be. I did have the Mitsubishi company size the system for me. They did a walk through of basically an identical house. So I really do not know if they are just trying sell me something I do not need. It hard to get unbiased opinions for sales people. Especially down here(mx).

Also do you have any other recommendations for suppliers other than sunelec? or do they basically hold the best prices.


All this said I may opt for something on the scale of 8kw system probably not anything larger to start out. I really depends on the budget for A/c more insulation in the house and other reduction in consumption spending. What is all costs. Obviously I rather spend it in conservation first, then see exactly where that leaves me with for $$$ solar.

What is the average energy production of your system in May. For a full sunny day? Just to get an idea. I know my system will be less efficient. With batteries and all.


Anyway, thanks for the help, as it is greatly appreciated. Especially from someone that lives in a similar climate(that is not a salesman).

I did vacation rentals for about 7 years ( I owned a condo in FL when I lived in MA )

Renters don't care or think about anything, they will plug in 5 hair dryers and use them at the same time, they leave windows and doors open for "fresh" air and make the AC run non-stop, they leave everything on all the time ... they have no concept of off grid living and are paying for the home for that week so will think they have paid to use it as they see fit

As for the AC brand, shop by SEER rating, not manufacture .. for Offgrid I would go SEER 16-17 minimum, and if you can afford it do Geo-thermal

You need to really get into how the home is constructed, you need R11 for the walls and R40 for the roof, double pain windows ect if you want to even have a chance on powering by offgrid.

Have you even looked into the inverters and charge controllers you will need? .. you talking about a whole house system, for example, you will need a Xantrex XW-6048 type system, at minimum a pair of them

Look into Solar thermal for Hotwater

Better your dreams be crushed now and either, do it right or change your expectations

totally understand. It is better to be brutally honest.

I am actually thinking of the outback system. Thinking of atleast 2 fx80's. Depending on system size.
Based on your question you suggest going with Xantrex products?

Have not actually sized my battery system, as it will wait till I have decided on panel array.

No I totally understand about. Rentals. I currently have rentals here as well.

There will not be hair dryers. That way cause someone a little grief. But life will go on. I will not stop people from bringing them, but definitely limits some usage. A towel is not something horrible to use to dry hair. Others will be coffee pot will be for gas stove not electric. All the appliances will be carefully picked, obviously I do expect them to be abused sometimes. But with a rental you kind of control what is in the house. It is rare that a guest will drag around tons of energy sapping products.

The city multi system I am looking into is a ductless system. It is large multi split system with copper tubing connecting inside units to outside. This way duct work which is so important will not ruin my efficiency, as here I am sure they will screw duct work up.

Oh solar heating yeah. That is definitely happening. No reason not to here. Especially in a climate like this, with no freezing the system is very simple and I know a lot more efficient then PV.

The FX80 are charge controllers, I was refereing to the inverters, Outback are 3.6kW max each and only 120V, since you running both 120/240 ( AC ) the only option is the WX-6048 inverter. The inverter will handle on demand turning on/off the generator.

For Charge Controllers I would suggest the WX one, I am biased as its partly my design working, its also convection cooled ( no fans ) and best in class Mppt performance

Your looking at a very, very large system, you should really look at a pacakged XW system, 12kw ( pair of XW-6048's, probably 3-4 XW mppt charge controllers, nice thing about the XW system is you can get the BOS box that simplifys all the AC and DC breakers and interconnects ... but warning, this is a VERY advanced project you concidering and NOT something a first time user should do.

Expense wise, I'd say your looking at probably near 100K when you add in the batterys, generator, all the balance of system parts .. unless local power is 1.00 watt you much better off with grid power and again, you can't control the renters, no matter what you think you can do, they will find some way to exceed the systems ability and you better have a backup plan when the inverters shutdown due to,

no fuel for the generator
Batterys die from abuse
inverters trip on overloads

ect ect

It is a doable project, but very expensive, very technical to get it all integrated and almost 100% for sure not cost effective for return on investment. You might also be VERY concerned about theft, a 100K system is a 30 year mexican salary for the taking when your not around

Local power stops atleast 1mile short of property. If I had access I would definitely use it, but do not. This is not for cost savings, it is lack of options.
IF worst case, I will just make a large battery bank and generator and just run a generator. Obviously need other electronics, but can save tons compared to a 12kw panel system. Could run the generator for quite a while for cost difference.
A 10kw propane generator is very inexpensive. Obviously a bit expensive to run but I believe can fall below $1kw. I can not remember the numbers.

I totally understand about renters, but there are certain things that can be done. Like telling them said ROOM A is wired with senors. If doors, and or windows stay open ROOM A a/c will shut down. Wanting the A/c they will get it.
The Multi City a/c is actual a system that can be controlled very intricately.
I do not expect to control the renters. But after my experiences If i say doors need to be closed to run a/c, and see no objection, I see no issue by putting cut off switches and sensors.

Yeah as for theft , it would be very unlikely in the area the house will go. Not saying it could not happen as mexico is FILLED with thefts. But it is a residential section with "good" neighbors. It also will have a caretaker year round. Things stolen are usually at ground level and something quick. Being batteries probably at ground level. I was actually thinking of large forklift type batteries. Something like a single battery with a 1000AH @48v that is rated at 6 hours not normal 20 hour rating. Anything up high actually is very safe.

Obviously that would not eliminate a caretaker for stealing panels /, but in that aspect I am safe. My caretaker is someone I have known for roughly 5 years. But he actually earns 15K a year as caretaker. Which is a bit higher than the normal wages. Although Cancun wages are very high in comparison to the whole country.

As for generator, yeah I was planning on having it automated. That would make it very easy. Hook it up with a propane tank of about 1000gallons and I should be good for a while. Propane tank passes at least 2 time a month if not more. ANd can schedule it for any day. Fuel is not a problem.


ANyway thanks for the recommendations about the xv system. I was looking at outback as that what the guys down here are used to dealing with.

As for installation, yeah I will not be doing anything electrically. I could do the panel mounting and running of those wire to near the controllers, inverters, and batteries. This would just be to reduce installation work and it is fairly simple labor work as in comparison to the actual setup.

I know enough to actual hire someone.

Anyway thanks again. I am sure I will be back again in the future.

I think your missing a key point.

The Batterys power an inverter which provides the AC, the Generator must go thru the inverters and the Outbacks can't handle that sized generator or handle 240VAC loads from the generator as they are 120V inverters ( no 240 ac )

1000ah for a whole house system is a small battery bank, your AC will kill that in 10-12 hours

I would recommend you hire a Off-Grid PV firm to design a system for you, this is not a grab a couple of parts toghether cabin system, your looking at providing all the homes needs from alternate generation and you have to have a system that is balanced.

Forklift battery are a poor choice, the self-discharge rate will waster fule/solar and since they are NOT sealed, will require weekly maintance ... you need AGM's and probably about 50K worth of them to run a home with AC.

Generators that are rated to run for more than a few hundred hours ARE NOT cheap. Your probably looking at 15-20K for a unit you acan run at medimum duty-cycles and you since they are mechanical, they will require regular maintance

whatever you decided, keep in mind, if you cut corners thinking you will just add stuff later, you will basically lose the monies invested. A cheap generator will die, a two small or wrong battery bank will die, undersized inverters will die ..

Design it once and correct, if you don't like the numbers then you can't do the project, thinking otherwise will just lead to endless problems or worse

I was not referring to just one 48000kwh of charge but actually that was to be the kind of size of battery. But reread my post and it does appear that I was just one battery system. Something you need a forklift or heavy equipment to move. I was thinking of something in the lines of 250,000kwh(`5200Ah @48v ) in total. but really that is something to size after I settle on solar panel system.

I WAS thinking of outback till you pointed me to the xantrex. I Was thinking outback as that is what ALL the solar installer down here deal with. At least all the ones I have visited which were all the ones that I could find. And I mean All I could find over a 3 hour car ride in ALL direction. Just not to many place here that deal with it. I figure If I was going to use what they are used to they would probably get it right first try rather than much of Mexican services down here is a 2nd or 3rd time around.

I know that the forklift batteries self discharge at a higher rate, but they normally take a much larger charge rate as well. So if I do charge them with a say 10kw generator, they can handle the whole charge of the generator. I have not actual run the numbers to see what I would be limited to(if any) if I used sealed batteries. From what I have understood is even with the larger generators. It is a all or nothing system, so if they are running them and do not use the capacity it will be lost. I figure my house to max out at about 5kw or power usage down to a normal of about 2.5kw. Or no ac. 1kw real rough numbers. Obviously I will lose a bit of power with this type of battery, but they from all I have read last considerably much longer. Kind of combat the heat down here, and probably run them past 50% DOD. Also the water levels do not concern me too much. Maybe they should and I am just ignorant to the need, but I figured that the weekly schedule of the grounds keeper would be to top them off. Obviously it would not be something to mess around with. Actual quite serious. But once trained it should be a simple process. At least that is all that I have read. The idea with the batteries as well is that I believe the forklift type can be located at a significantly cheaper price, which may offset the energy which they drain/waste. Still looking for suppliers here as well in the Florida before I settle on any part of the systems. I have located suppliers in other parts, but really does not help me if shipping of batteries or other parts is going to be super expensive.

Obviously all I have posted is just simple reading and none ( 0% ) is hands on. As such I really do appreciate your help, and I am in constant contact with "the experts" here.

Being that most "the experts" here are idiots on almost all topics I definitely was and still am looking for outside experiences.

I definitely thank you. For the time you put in here to answer my questions.