Building new Off Grid Home in Panama

niel wrote: »

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

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.

Cariboocoot wrote: »

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

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.

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.