Building new Off Grid Home in Panama

Panamretiree

Re: Bulding new Off Grid Home in Panama

Blackcherry04 wrote: »

I get what your up against down there. I wouldn't underestimate how nice it would be to have that Grid Power brought into the property if you can. It would open a whole range of options that just having a generator as a backup wouldn't, it would allow you to size the generator differently and just include more options for you. You have to think long term of things you cannot foresee right now.

BC - We will have grid power into the house. We only expect to have the AC units on it. The main part of this is to be as much off the grid as possible, because we want to be the kids on the block with power when everything goes black, and if this week is any indication, it will. We North Americans tend to find it warm even after being acclimatized. At the present time we will not be having it tied onto the solar power system, but that can change in very short order. Like you say, we have options and we are closing no doors.

Cheers

Ernest

niel

Re: Bulding new Off Grid Home in Panama

i just have to say thinking out loud what i would do if i were moving to that region of the world and this would also depend on the view from the location as there may be obstacles such as trees or other buildings and even local weather conditions at certain times of the day. anyway, i would put in 2 separate controller and pv systems with one facing easterly and one facing westerly. they would be angled up from horizontal only by about 20-30 degrees in their respective directions. this is due to the fact that near the equator the sun comes up almost due east and rises straight up from their until solar noon and then heads back almost straight down in the west.

now one flat pv system is still good down there, but the above is what i would do.

Panamretiree

Re: Bulding new Off Grid Home in Panama

niel wrote: »

i just have to say thinking out loud what i would do if i were moving to that region of the world and this would also depend on the view from the location as there may be obstacles such as trees or other buildings and even local weather conditions at certain times of the day. anyway, i would put in 2 separate controller and pv systems with one facing easterly and one facing westerly. they would be angled up from horizontal only by about 20-30 degrees in their respective directions. this is due to the fact that near the equator the sun comes up almost due east and rises straight up from their until solar noon and then heads back almost straight down in the west.

now one flat pv system is still good down there, but the above is what i would do.

Interesting concept. Understand what would be achieved, but what would be the advantage of having two CC and separating the into two, one on the back and one on the front. You are correct that the sun comes directly over the house. I intend to have the panels separated into two groups, half on the front and back respectively, with a down angle of ~3 to 5 degrees (sort of following the roof lines), mostly to keep them clean. This should allow the panels on the front of the house to catch more of the morning sun until high noon, and the aft panels to catch the sun as it goes down in the west.

There is sun from 0700 to 1700 each day, clouds and such as MN sees fit, but the orientation of the house could not be better.

Cheers

Ernest

inetdog

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

Interesting concept. Understand what would be achieved, but what would be the advantage of having two CC and separating the into two, one on the back and one on the front. You are correct that the sun comes directly over the house. I intend to have the panels separated into two groups, half on the front and back respectively, with a down angle of ~3 to 5 degrees (sort of following the roof lines), mostly to keep them clean. This should allow the panels on the front of the house to catch more of the morning sun until high noon, and the aft panels to catch the sun as it goes down in the west.

If the array is large enough, you may want to use two CCs to carry the whole output when the sun is hitting both sets.
Other than that,
1. if the panel count of the two arrays is the same and
2. one controller can handle the combined current and
3. there is no partial shading of either panel at any time when it is producing significant power,
then you can use one MPPT input for both.

And the reference really is to partial shading. The fact that one entire array will lose sunlight while the sun is strong on the other is not a concern, since you would not be getting much power from the first array as the sun is getting close to that array's "horizon."
The difference in light on the two arrays will cause the current to be different, but not the voltage, so the MPPT voltage for one will still be the MPPT voltage for the other.

It would give you some redundancy in your system if one CC fails and has to be replaced or repaired.

westbranch

Re: Bulding new Off Grid Home in Panama

IIRC Chris Olson has a posting about this very setup 1 @ E, 1 @ W orientation. His observation was there is no appreciable loss of total daily production. I don't remember if he looked at total hrs of input.

Panamretiree

Re: Bulding new Off Grid Home in Panama

The roof is on the house. Will take pics and post.

Will be looking into getting brackets made for the panels.

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

Some pics of the roof and its structure. Now I can get on with the panel supports, have a good idea of what I need.

Pics from the front and south side, and the underside structure:

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Cheers

Ernest

niel

Re: Bulding new Off Grid Home in Panama

addition to my comment,
i really wouldn't need a separate cc on each array unless each were that big. 48v battery systems will allow for huge amounts of power through a classic as you already know. it would be more for redundancy as if one side fails the other still is going. of course one can just have a spare laying around, but it may be better to run 2 classics at lower power levels than to run the pants off of 1 at a larger power level with the other as a spare.

now the purpose of the tilt would be to maximize the collection over a longer spance of the daytime hours.

seeing the building it opens lots of questions and you may have already touched on some of it, but i don't want to go back and reread. such questions are like do you opt for vapor barriers in the floor or walls? how are you to insulate? extra insect protections for the building as i know insects are numerous in tropical areas especially ones like termites.

very wet and hot areas can present problems. florida is such a place, but even they do get a bit of relief during winter that you will not. also of note is to watch for vegetative growth that may interfere with pv production and this will be more prevalent to your eastern and western directions as the sun will be lower to the horizon then. also, leave yourself options for future expansions of your system as everybody winds up using more than initially figuring on and a larger array may allow for large loads to be better utilized during the day while still having enough to fully charge the batteries for overnight needs.

solar_dave

Re: Bulding new Off Grid Home in Panama

I don't see anything in that construction that would interest the termites so far.

Metal Roof, I bet that gives some of its own strength to the roofing.

niel

Re: Bulding new Off Grid Home in Panama

it's not done yet dave. he will have some wood in there eventually.:roll:

westbranch

Re: Bulding new Off Grid Home in Panama

(Always the) Optimist...:p

Panamretiree

Re: Bulding new Off Grid Home in Panama

niel wrote: »

it's not done yet dave. he will have some wood in there eventually.:roll:

Yes, but it will most likely be teak, and bugs don't like it. Thankfully the price of the house includes teak.

Wood will be used for the bathroom cabinets, kitchen cabinets, doors and door frames, closets in the bedrooms. That's it I think.

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

solar_dave wrote: »

I don't see anything in that construction that would interest the termites so far.

Metal Roof, I bet that gives some of its own strength to the roofing.

The metal structure underneath is extremely lite, but strong. Some of the pieces of the structure are over 20 feet long and one persons can carry it. The corrugated roof material is a mixture of cement, glass and cloth. Reminds me of a fiberglass mesh with a non-glossy gel coating.

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

niel wrote: »

addition to my comment,
i really wouldn't need a separate cc on each array unless each were that big. 48v battery systems will allow for huge amounts of power through a classic as you already know. it would be more for redundancy as if one side fails the other still is going. of course one can just have a spare laying around, but it may be better to run 2 classics at lower power levels than to run the pants off of 1 at a larger power level with the other as a spare.

The thought right now is to have two smaller arrays of 6 panels each, one front - one back, with two CC, regardless of voltage. It does give me redundancy, can always hook the panels into a different configuration if a CC were to go south on me, and may very well optimize the system. Would not want to have one just sitting around so to speak. No free lunches, everyone works.

now the purpose of the tilt would be to maximize the collection over a longer spance of the daytime hours.

This has been discussed. My thinking right now is to have the two small arrays at the same angle as the roof that is ~13 degrees. As you mention, this would maximize morning and afternoon sun. Both arrays should produce power one better than the other, but the controllers can do the balancing act for the system. It will also simplify the installation. If I see that the arrays are not producing as expected, the tilt of the arrays can always be modified.

seeing the building it opens lots of questions and you may have already touched on some of it, but i don't want to go back and reread. such questions are like do you opt for vapor barriers in the floor or walls? how are you to insulate? extra insect protections for the building as i know insects are numerous in tropical areas especially ones like termites.

The only insulation will be in the ceiling for sound insulation and to keep the heat from the attic out. Not much can be done about the insects, they were here long before we were and will be here long after. Vapour barriers are not used here, even had resistance to putting in roof vents. Some of the building requirements that we come to expect up north are not common place down here.

very wet and hot areas can present problems. florida is such a place, but even they do get a bit of relief during winter that you will not. also of note is to watch for vegetative growth that may interfere with pv production and this will be more prevalent to your eastern and western directions as the sun will be lower to the horizon then. also, leave yourself options for future expansions of your system as everybody winds up using more than initially figuring on and a larger array may allow for large loads to be better utilized during the day while still having enough to fully charge the batteries for overnight needs.

We had a good look at the roof yesterday and two small arrays of 6 panels takes up a lot of real estate. I will be placing the arrays on the long side of the roof. If expansion is required have the ends to use, and 4 panels will easily fit there.

12 panels will give me two small arrays of 1830W each. Well within the specs for a 48V or 24V system. Adding four more panels in the future would also not be a problem for either voltage system. The only issue with this is sourcing panels here in Panama to match, could be tricky.

As you mention, redundancy is an issue down here. Getting replacement(s) parts or equipment is not that easy or fast. I mentioned that on another forum, and it would be good to take my own advice in this manner.

Time to go. The birds are waking up and the roosters will be crowing soon.

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

westbranch wrote: »

(Always the) Optimist...:p

WB - you seeing ground up there yet, or are you still wearing your woolies?

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

Question:

Scenario:

Expand an array with panels that are not exactly the same as the originals. Configuration 2 panels in series, 3 parallel modules for an array size of 6 panels. Add 2 panels connected in series to have 4 parallel modules for an array size of 8 panels.

Connect the new panels to the system through the combiner box.

If a person were to expand the array in this manner even if the panels are not exactly the same as the other panels in the array, can this be done - will it work?

Cheers

Ernest

Blackcherry04

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

The metal structure underneath is extremely lite, but strong. Some of the pieces of the structure are over 20 feet long and one persons can carry it. The corrugated roof material is a mixture of cement, glass and cloth. Reminds me of a fiberglass mesh with a non-glossy gel coating.

Cheers

Ernest

Any idea how they do the roof penetrations for Solar PV racking ??

Cariboocoot

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

WB - you seeing ground up there yet, or are you still wearing your woolies?

Cheers

Ernest

It was 32C up here on Monday. What are you talking about?

Cariboocoot

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

Question:

Scenario:

Expand an array with panels that are not exactly the same as the originals. Configuration 2 panels in series, 3 parallel modules for an array size of 6 panels. Add 2 panels connected in series to have 4 parallel modules for an array size of 8 panels.

Connect the new panels to the system through the combiner box.

If a person were to expand the array in this manner even if the panels are not exactly the same as the other panels in the array, can this be done - will it work?

Cheers

Ernest

Couple of different ways, depending on how far off the new panels are:

1). If the 'new' array Vmp is withing about 10% of the old they can be parallel without any difficulty.
2). The absolute sure-fire method; new panels get new controller.

Panamretiree

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

It was 32C up here on Monday. What are you talking about?

Checked out the weather up there - sunny and ~18 deg C for the next few days, nice.

westbranch

Re: Bulding new Off Grid Home in Panama

ya, it turned cold so fast might have to break out the long pants again....
my bees are lovin' it! They like it mid teens to low twenties, above 25 they have to ventilate the hive.

niel

Re: Bulding new Off Grid Home in Panama

as coot said the string voltage must match within approximately 10%, but i like the tighter 5% tolerance range myself. the closer the voltage, the better it will be with less in losses due to mismatch. ultimately in the case of not being able to suitably match the pv string voltage then one could use a separate cc on the newer array. more expensive that way, but surefire.

my post was not to tell you what to do, but more of what i would do. it would not be wrong to do it slightly different if you want to and it is your $ and your decision as to what's best for you. i do hope you understand where i'm coming from with my post as it is to help get the most power and reliability even though it could cost a bit more. thinking of the future of a system is good to do too.

westbranch

Re: Bulding new Off Grid Home in Panama

and if expansion is far enough down the road you might have the option of a Classic Lite or "The Kid"...and the "Whiz-bang"

Panamretiree

Re: Bulding new Off Grid Home in Panama

niel wrote: »

as coot said the string voltage must match within approximately 10%, but i like the tighter 5% tolerance range myself. the closer the voltage, the better it will be with less in losses due to mismatch. ultimately in the case of not being able to suitably match the pv string voltage then one could use a separate cc on the newer array. more expensive that way, but surefire.

I was wondering how close a tolerance I should look for.

my post was not to tell you what to do, but more of what i would do. it would not be wrong to do it slightly different if you want to and it is your $ and your decision as to what's best for you. i do hope you understand where i'm coming from with my post as it is to help get the most power and reliability even though it could cost a bit more. thinking of the future of a system is good to do too.

I took your post as constructive, and once I thought about it, and the direction I am heading it made sense. With this in mind, I was up early this morning and watched the sun come up. Between 0730 and 0800 the sun was directly on the front side of the house. I did not look at the backside. With the panels installed at the roof angle, it makes sense to grab as much sun early, even though between 1000 and 1400, the sun will be mostly overhead and both small arrays will be powering the system. I will loose some performance between 100 and 1400, but gain at the beginning and end of day. I also think that getting the power flowing into the system as soon as possible in the day is good. Never know what the remainder of the day will bring.

It also made sense from a redundancy point of view. Can't just phone up a supplier and have a new unit delivered. If one of the CCs does go down, I can still operate with a few modifications until a new unit gets here.

Doing it in two smaller arrays also allows for maximum input to the system, and if I increase the battery bank in the next iteration, I have the panels to support.

Not to worry, I appreciate all comments and suggestions, and personal opinions. In the end, we will make as informed a decision as possible based on all aspects and facts, and hopefully we have hit enough high points that we will be satisfied with our decision.

Cheers

Ernest

Panamretiree

Re: Bulding new Off Grid Home in Panama

westbranch wrote: »

and if expansion is far enough down the road you might have the option of a Classic Lite or "The Kid"...and the "Whiz-bang"

The MidNite web site Classic String Sizing Tool does a CC sizing based on panel data and gives CC recommendation on Classic 150/Lite. I take this to mean that a person can use the 150 or the 150 Lite as the CC. Have looked at the comparison between the two and it would seem that the standard Classic gives a few more accessories that would allow for additional monitoring if one is so inclined. I also don't quite understand the HyperVOC technology being talked about.

I read somewhere about "The Kid" and the "Whiz-bang" but really did not understand what was being bantered around.

Cheers

Ernest

vtmaps

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

I also don't quite understand the HyperVOC technology being talked about.

I read somewhere about "The Kid" and the "Whiz-bang" but really did not understand what was being bantered around.

If you exceed the maximum input voltage of some controllers, they are destroyed. The Midnite controllers have HyperVoc which means that when you exceed the input voltage they stop working, but are not damaged.

The kid is an upcoming small (but stackable) controller. The whiz bang is a shunt based monitor with which the classic will be able to properly implement 'end amps' charging.

--vtMaps

niel

Re: Bulding new Off Grid Home in Panama

elaborating on what vtmaps said i, hopefully, can simplify it for your understanding. a regular controller has a voltage limit and once the limit is exceeded you can damage the controller. some of these may operate right until failure. the classic states the voltage operating limit by model and then gives a buffer zone where the classic will not be operational if that voltage is exceeded, but will not be damaged and is based on the battery voltage being used. i have a classic 150 with a 12v battery and it will operate to 150vdc. now some of us in colder regions could see pv voltages rise on very sunny cold mornings before the sun warms up the pvs and the array if designed close to the 150v area during warm days could exceed the max voltage it will operate at on occasion. the cc will not be damaged if the excursion does not exceed 162v. same classic 150 on a 24v battery bank can go to 174v before damage to the controller will occur, but power production still stops at 150v.

you won't need to worry about that cold doing that to the max voc, but edge of cloud can magnify the available sunlight too. they do specify that the max voltage this buffer can be is 48v and would be for a 48v or greater battery bank voltage. now one does not want to design an array to go above the max operating voltage of the controller for in every case you will not be getting power production during that said condition. it is just added insurance midnite has that the cc will be fine against a rare event you had not designed your pv system for.

Panamretiree

Re: Bulding new Off Grid Home in Panama

niel wrote: »

elaborating on what vtmaps said i, hopefully, can simplify it for your understanding. a regular controller has a voltage limit and once the limit is exceeded you can damage the controller. some of these may operate right until failure. the classic states the voltage operating limit by model and then gives a buffer zone where the classic will not be operational if that voltage is exceeded, but will not be damaged and is based on the battery voltage being used. i have a classic 150 with a 12v battery and it will operate to 150vdc. now some of us in colder regions could see pv voltages rise on very sunny cold mornings before the sun warms up the pvs and the array if designed close to the 150v area during warm days could exceed the max voltage it will operate at on occasion. the cc will not be damaged if the excursion does not exceed 162v. same classic 150 on a 24v battery bank can go to 174v before damage to the controller will occur, but power production still stops at 150v.

you won't need to worry about that cold doing that to the max voc, but edge of cloud can magnify the available sunlight too. they do specify that the max voltage this buffer can be is 48v and would be for a 48v or greater battery bank voltage. now one does not want to design an array to go above the max operating voltage of the controller for in every case you will not be getting power production during that said condition. it is just added insurance midnite has that the cc will be fine against a rare event you had not designed your pv system for.

Niel/vtmaps: Got it. Best to have the max array power slightly below or below the 150vdc limit for the Classic and not enter into this gray area because as you both state, the CC is not allowing any array current through; ergo, there is no free lunch, everybody works. This seems to be another good reason to have two smaller arrays and let the CC manage everything the panels can put out, knowing that the size of the array cannot max out the CC.

Cheers

Ernest

vtmaps

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

Best to have the max array power slightly below or below the 150vdc limit for the Classic and not enter into this gray area because as you both state, the CC is not allowing any array current through; ergo, there is no free lunch, everybody works. This seems to be another good reason to have two smaller arrays and let the CC manage everything the panels can put out, knowing that the size of the array cannot max out the CC.

Just to be clear... You changed the discussion from 'maximum input voltage' to 'maximum watts or current'. They are very different types of maximums, and the consequences of exceeding them are different. For example, four of these 130 watt panels in series (520 watt array) will drive a classic beyond hypervoc before the sun comes up.

--vtMaps

Cariboocoot

Re: Bulding new Off Grid Home in Panama

Clarifying what vtMaps said: four of them in series on a Classic 150 would be a problem. 4 * 41 Voc = 164 Volts. The controller would not be damaged, but at that point it would be shut down.

Basics of panel configurations on MPPT controller: http://forum.solar-electric.com/showthread.php?16241-Different-Panel-Configurations-on-an-MPPT-Controller