Building new Off Grid Home in Panama

Cariboocoot · April 2013

Re: Bulding new Off Grid Home in Panama

The Smart Gauge diagrams are about keeping the wiring resistance on multiple parallel batteries (or battery strings) as equal as possible in order to keep the current even through all. Not doing so can lead to wider discrepancies in SOC and condition between strings. This is more important on lower system Voltages than higher ones, but always a good idea.

Problem with having a battery system that will last for five days is that you need a very large battery bank and then a very large solar array that will recharge it. If you get sun most days this is money down the tubes (unrealized capacity). Even if you don't, starting a generator every third day to Bulk up the batteries is far more economical than putting in the extra capacity & solar.

My standard recommendation is to go for an average 25% of battery capacity usage for a day. That way you have a second day available before you hit 50% DOD (less whatever sun you did get). One day three start the generator.

If you're in an area where weeks without sun is likely, you're in a bad solar area and it isn't practical to try and use it. Better to consider another power source.

vtmaps · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

Problem with having a battery system that will last for five days is ...

Another problem is that when your battery bank is large and you have multiple sunny days in a row, your overnight discharge cycles may be very shallow (100% SOC --> 95% SOC --> 100% SOC --> 95% SOC --> 100% SOC). This is not healthy for batteries and can cause lead oxide clumps to form on the plates.

Generally, the shallower the daily discharge the more cycles the battery will have in its lifetime, but this relation breaks down with very shallow cycles.

Overusing and underusing batteries is not cost effective. Cariboocoot's "standard recommendation" of 25% usage per day is a balanced and cost effective approach.

--vtMaps

inetdog · April 2013

Re: Bulding new Off Grid Home in Panama

westbranch wrote: »

Re the Oral B: is it possible to use it for 3 - 4 days and then plug it in to recharge.

I do that all the time and have never had any problems. Depending on the design, there may not even be much of a power drain if you leave the charging stand plugged in and just do not put the toothbrush into it. But unplugging the charger is best.

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Thanks for the input regarding the reserve capacity. Won't know actuals until we are in our house, but hopefully have done enough homework to ensure we get off on the right foot, so to speak.

Also read about the HuP battery systems. A fellow on another forum mentioned it. Seems to be an impressive system, should be for the price. Too bad its FLA, we are looking at AGMs. probably best for s laymen.

I'm also trying the unplug on the Oral-B.

Cheers

Ernest

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

Thanks for the input regarding the reserve capacity. Won't know actuals until we are in our house, but hopefully have done enough homework to ensure we get off on the right foot, so to speak.

Also read about the HuP battery systems. A fellow on another forum mentioned it. Seems to be an impressive system, should be for the price. Too bad its FLA, we are looking at AGMs. probably best for s laymen.

I'm also trying the unplug on the Oral-B.

Cheers

Ernest

If your planing to live off grid you should think long and hard about even considering AGM batteries, there are places for AGM batteries, off grid is not one of them. There is no way to ever keep up with the charging variables with PV Solar and AGM's, especially with the first set.

vtmaps · April 2013

Re: Bulding new Off Grid Home in Panama

Blackcherry04 wrote: »

If your planing to live off grid you should think long and hard about even considering AGM batteries, there are places for AGM batteries, off grid is not one of them.

I think AGMs will prove to be a very expensive mistake. It may take a couple of years of slightly under or over charging them before you realize your mistake. When you do realize, it's too late. With flooded batteries you can (with an hydrometer) catch your mistakes while they are still correctable.

--vtMaps

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Even if you disregarded the issues with AGM's and Ambient temperatures, the logistics of getting a set there would be a nightmare. I'd have anything I bought " Dry Shipped " ( electrolyte separate ) and activate them on site. All most everyone that has had batteries shipped off shore has had major issues, they just can't sit for long periods waiting to be used or charged and maintained.

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Thanks for the input on the batteries. Will review my notes and look at the batteries again.

Any thoughts on using bars to connect the batteries instead of cables.

Cheers

Ernest

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

Thanks for the input on the batteries. Will review my notes and look at the batteries again.

Any thoughts on using bars to connect the batteries instead of cables.

Cheers

Ernest

Personally I would never use them and when I find them on a bank, I remove them if I can. As a battery ages and heat cycles from charging things expand and contract, cases bulge and the positive post will protrude. A bar does not give, I have seen posts ripped completely out of the battery case. To even remove them, sometimes you have to beat them off with a hammer.

Another issue is you really need to have at least a 1" air space in between each battery for cooling. If you cube them up in a solid block, your looking for trouble. If you need to remove one battery for some reason, you have to take the whole bank apart.

Lastly, unless the batteries you choose stay to the exact specifications they'll never fit you next set of batteries.

Cariboocoot · April 2013

Re: Bulding new Off Grid Home in Panama

I've tried batteries connected with bars.
Guess what? I'm using cables again.

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

I've tried batteries connected with bars.
Guess what? I'm using cables again.

I'v seen some major fancy ones, factory made over the years, 3/8 x 1" copper all machined on a mill and counter sunk holes. Brass ones broke and bent on a brake, in the end they all ended up in the scrap box.

It's hard to beat a proper made set of cables, where the lugs fit the bolts and heat shrink that seals lugs against corrosion.

Surfpath · April 2013

Re: Bulding new Off Grid Home in Panama

Blackcherry04 wrote: »

Even if you disregarded the issues with AGM's and Ambient temperatures, the logistics of getting a set there would be a nightmare. I'd have anything I bought " Dry Shipped " ( electrolyte separate ) and activate them on site. All most everyone that has had batteries shipped off shore has had major issues, they just can't sit for long periods waiting to be used or charged and maintained.

It's all about vigilance and trust

I recently shipped a bank of electrolyte filled FLA batteries offshore. After 5 months I appear to have a functional, appropriately commissioned, bank.

Recommendations for shipping FLA's 'overseas'

Don't have them shipped directly to a shipper. As discussed elsewhere on the forum, most FLA's seem to leave the factory at 80% SOC. This means, by the time they get to the shipper, then to the boat/plane, then in transit, then to customs, then to you they will likely be at a lower SOC for a long period of time. And we all know what this means.
Have them sent to a trusted 3rd party or knowledgeable friend who you know will be able to boost charge your batts to at least 90%. A thought: If you could have your commissioning charge done in the US that may even be better.
Have this 3rd party inspect & hydro each cell for you to make sure that all looks ok before performing this boost (or commissioning) charge.
Be ready to commission charge your bank as soon as it gets to you. This means setting up the rest of your solar gear ahead of time, or obtaining a ~20amp+ (6v/12v) battery charger.
Make sure the batteries are well crated, with lots of arrow (upright) signs.
Once that bank leaves the US (or wherever), forget about your battery manufacturers warrantee. It's unlikely that you will be able to economically return defective batteries.

I've read about others who shipped their batteries 'dry' and had all sorts of problems finding the right kind/mix of electrolyte at the destination point. Also most shippers charge per weight & volume. Shipping the electrolyte separately will only add to your bill.

Perhaps shipping 'dry' is not that all difficult, but I think FLA's can be shipped filled if the right steps are taken.

I don't have them but I can understand why other posters say AGM's are expensive, mysterious, slightly odd, beasts for a first bank. My neighbor here killed his first set of AGM's at the end of year 2. If you 'accidentally' murder your bank, FLA's are the cheaper mistake.
-SP

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Short note on progress.

Started doing a light load test using 1.5W LEDs. First part done with one light only, second part in progress with two lights being monitored. Found the 1.5W LED with the standard socket fitting to use 2.4W to give 1.5W. Changes the pad analysis a bit. As said below have to allow for growth.

Have also bought 2W and 4W LEDs with the GU10 bayonet mount. This will be started tomorrow.

The roof should be going on next week, will have pictures of it. It is a rather lite structure, but since there are no real loads, it doesn't have to be too skookum. Will post pictures when it gets on.

I read an article on solar power down here and the article mentioned that solar panels should be installed practically horizontal and this is good year round.

I am looking at the battery issue, but have noticed that there are several people posting that use AGM batteries for their systems. I do understand the inability to monitor and maintain the battery system is not as good with AGM, but would expect some sort of dependability from today's AGM batteries. Having said this, have no problem either way, just wish I had spent more time with the electricians in my Navy days.

Looked into the 48 to 24 VDC converters, made in Canada no less. Have sent the company an email requesting some information regarding how I intend to use them. I would like to have three 24 VDC ceiling fans (0.75 amp each) on one and two fans respectively on two others. Look forward to the answer.

If the converters work out, still looking at a 48 VDC system. Won't have to upgrade later, smaller wire sizes, and one inverter for total load.

Have been reading the different forums and find them very informative and educational.

Enough for now.

Cheers

Ernest

BB. · April 2013

Re: Bulding new Off Grid Home in Panama

You might try for a 5 degree tilt... The wind and rain will do a better job of keeping the debris/dust off the panels. Would be a big deal if the array is mounted on the roof and you don't have any easy access for broom and water to keep brushed clean (if you have leaves that collect on the panels, that can be a big killer of your output). Also gives you some ideas of having a hose bib+catwalk near the array if that will make cleaning easier (buck with soap and water, squeegee if you have hard water, etc.).

-Bill

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Thanks Bill. It is quite dusty down here during the dry season so it will be advantageous to have a bit of a tilt on the panels.

Also researching ways to get cool air into the house. Can't see us putting in a big enough system to handle an AC load. It's not only for creature comfort, but during the wet season, humidity can be a problem.

Have found sites related to heat resistant paint coverings that can prevent the ingress of heat by 10 to 20 percent. looking into these areas as well.

Cheers

Ernest

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Regarding AC units. We installed two 9000 BTU split AC units in our beach house that we are now selling. The beach area is hotter than in the Las Uvas area by some 10 to 15 degrees F. Anyhow, when installed the installers put a clamp meter onto the 220 VAC supply and with two units operating the amp reading was at 8, not bad, 4 amps each when operating.

Still a hard sell to use on AC:

4 amps * 220 VAC = 880 watts

We would need them for about 3 or 4 hours during the wet season to dehumidify, and for ~2 hours during the dry season. Since we aren't in our house yet, don't know what the natural ventilation will bring.

Going to also hook up an anemometer to check out the wind speed here. Have read that you should have wind at >12 mph for a minimum of four months of the year to make it feasible.

Being retired gives a person a lot of time to do lots of "stuff". Don't know how I did it when I was working.

Cheers

Ernest

BB. · April 2013

Re: Bulding new Off Grid Home in Panama

Ernest,

We have had discussions before here about insulating paints... And so far, none of us are convinced that they work.

Insulating paint?

That being said, the paints containing aluminum may provide some reflective properties. One person painted the backside of the roof and felt it reduced attic temperatures a lot.

Regarding insulation/humidity control... A well insulated home may do OK on solar power with the new, very efficient, mini-split A/C systems.

And, if you can ever justify bring it down to Panama, a Heat Pump type water heater can give you hot water, humidity reduction, and cooling--All for less money spent on power just for hot water (similar if you get an A/C system that can be plumbed to heat water too).

There are retrofit versions of heat pump water heaters that can be added to an existing hot water tank (replace the lower heater element).

Hot Water Heat Pumps

If done "right", a water heater attached to the A/C system should be a wash or even reduce your power usage a bit (true "free heat") as long it generates enough hot water and you do not need the backup heater.

On of the old time posters here (solar guppy) believes that Heat Pump hot water is a better deal than Solar Thermal (he did like this vendor for DIY solar hot water).

-Bill

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

I am looking at the battery issue, but have noticed that there are several people posting that use AGM batteries for their systems. I do understand the inability to monitor and maintain the battery system is not as good with AGM, but would expect some sort of dependability from today's AGM batteries. Having said this, have no problem either way, just wish I had spent more time with the electricians in my Navy days.

Cheers

Ernest

I am going to give this a shot. Your designing a system around your loads, that equation is going to take you to a Battery Bank of a given size, let's use 800 amp hrs. That means if you pull it to 50% dod overnight you would have 400 amp hrs to use everyday from sun down to sun up. For the sake of argument you able to put back that 400 amp hrs everyday without any loses.

I am your banker, I put $800 in a checking account, I let you take out $400 everyday and you have to put back $408 every morning. The catch is you are never allowed to see the Balance in the account. I cheated you from the start I only put $780 in your account. Everyday I take out $10, but you never know whats going on, because you are never allowed to see the balance. At some point you are going to overdraw the account. This analogy is about what you deal with a AGM batteries. You never Know.

Your Battery Bank is like that checking account, with AGM batteries you never know where you are at. As batteries age they lose capacity, most manufacturers say that battery at 80% - 70% capacity is considered depleted, most solar people will cycle them longer, say to 50%. 50 % is only 200 amp hours out of the 400 you started with, 200 amp hrs is not enough capacity to make your system viable. Here is where you start to put the $$ per cycle cost and replacement costs into the cost of living off-grid.

FLA Batteries give you a better shot at analyzing their internal condition due to the fact that you can check the Specific Gravity ( SG's ) at intervals. As soon as you notice they are losing capacity, you take corrective action. Some AGM's will allow you to Equalize them like FLA's, but it is still a shot in the dark as to their real condition.

Just my $.02

Cariboocoot · April 2013

Re: Bulding new Off Grid Home in Panama

Which is why with AGM's a battery monitor is a really, really good idea. It isn't perfect (especially if programmed wrong), but it's better than going by Voltage alone. It will keep track of the Amps going in and out and compare that to the capacity to come up with a SOC "on the fly".

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

Which is why with AGM's a battery monitor is a really, really good idea. It isn't perfect (especially if programmed wrong), but it's better than going by Voltage alone. It will keep track of the Amps going in and out and compare that to the capacity to come up with a SOC "on the fly".

Sure it is, just another guess as to their real condition. Let's see, I took out 200, how many is that I need to put back in ?? Whats my Peukert's exponent, how does the heat in Panama effect me.

Not that it isn't a good Idea to have one, but they can be a false sense of security.
.

Cariboocoot · April 2013

Re: Bulding new Off Grid Home in Panama

Blackcherry04 wrote: »

Sure it is, just another guess as to their real condition. Let's see, I took out 200, how many is that I need to put back in ?? Whats my Peukert's exponent, how does the heat in Panama effect me.

Not that it's a good Idea to have one, but they can be a false sense of security.

Hence my remark about the need to be programmed correctly.
Oh, and you have to start out with fully charged batteries too.

On the whole I shy away from recommending AGM's unless there's a particular need for their advantages (sealed, high current handling, light weight).

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

Hence my remark about the need to be programmed correctly.
Oh, and you have to start out with fully charged batteries too.

On the whole I shy away from recommending AGM's unless there's a particular need for their advantages (sealed, high current handling, light weight).

We agree, People should buy what they like, but AGM's for off-grid is not a good choice.

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Thanks for the info Bill. Have to look at everything to get the inside cooler without the use of AC. Was at a friends house for dinner, cinder block construction the same as ours and the west wall in her bedroom was very hot - cinder block houses are heat sinks. This led to a discussion on this.

Storing hot water is not something you see here in a single dwelling. Hot water on demand systems are predominant, and a lot of houses with cold water plumbing only use the electric hot water shower heads - you can always boil water for dishes, etc. These are commonly known as widow makers - something like the average home ladder. If they are installed properly and "grounded" they are not an issue.

Not much insulation in these homes. had to arm twist the builder to accept our requirement for attic insulation and roof vents. They do not accept change very well here.

Will be doing a lot more digging. there has to be something or is this my third career starting.

Cheers

Ernest

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

BC - great analogy - what I get from these forums is everyone is trying to ensure that a person gets the best chance going forward. I totally agree with you, a little more work, but the end result is better. Thanks for your $.02 - it makes sense. I also think when I explain it to she who must be obeyed, I know where I will be heading. The better half wants this to work and does not want to revisit batteries in a year or two especially down here.

Now to redraw the equation to suit the requirement.

Cheers

Ernest

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Heat in Panama is a real issue. It stays fairly constant all year and it plays havoc with vehicles, equipment and people alike. Mother Nature down here plays no favorites.

Blackcherry04 · April 2013

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

BC - great analogy - what I get from these forums is everyone is trying to ensure that a person gets the best chance going forward. I totally agree with you, a little more work, but the end result is better. Thanks for your $.02 - it makes sense. I also think when I explain it to she who must be obeyed, I know where I will be heading. The better half wants this to work and does not want to revisit batteries in a year or two especially down here.

Now to redraw the equation to suit the requirement.

Cheers

Ernest

Brother, we all here want you to have the best shot you can have at having a very successful system, we're all invested in it. We pick at each other at times, that's the check and balance. To be successful you and your battery bank are going to be as one. FLA's require a little more work, but in the long run you'll understand why and what you get in return.

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot - right now I could do with some of that cooler air that you have up there. Drinking litres of water each day, some in the form of cerveza of course, can't replace a little cool breeze every now and then, but it is nice not to have to worry about your wardrobe - shorts, t-shirt and sandals only.

Right now I have no specific need for AGM batteries, I have a place in the shade, close to the inverter (15 to 20 feet), with lots of venting.

Since this a project even though we are going to live it, one needs purpose in life. The better I make this work, the happier the better half will be. On the other hand, why do it right the first time, we always seem to be able to do it right second time round and have the money for it - not this time though.

Cheers

Ernest

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

BC - Thanks for the support. There are a lot of expats here interested in solar power and possibly getting off grid, or supplementing there requirements. when the grid goes down, first though is to refrigeration. In this area and with this builder/developer, we are the first couple who are jumping into this and making sure it is successful - minus AC. We are being looked at as sort of pioneers because everyone thinks and is being told that it is expensive. It is, but the benefits down the road are sure to outweigh the investment today.

I realize that the batteries are the expensive side of the equation, not so much in the initial cost of the system, but that batteries are and will always be, the first victim of the system. The rest of the components will survive to fight another day when new ones are installed. Then we get to the weakest link in the system again, the batteries.

The truth is the weakest link is generally us, the human factor. I remember when cruise control came out on cars, trucks, etc. People actually believed they could put it in auto and leave the driving to Auto. All season tires, another myth, not good for summer, nor good for winter. Maintenance free products, a money maker for industry, nothing lasts forever, and the collateral damage due to this mindset, priceless.

Thanks for the input and subtle direction. Did want the easy way out though, just human.

Cheers

Ernest

Cariboocoot · April 2013

Re: Bulding new Off Grid Home in Panama

Panamretiree wrote: »

but it is nice not to have to worry about your wardrobe - shorts, t-shirt and sandals only.

That's exactly what we wear in Canada too! The polar bears think we're crazy of course ...

Panamretiree · April 2013

Re: Bulding new Off Grid Home in Panama

Cariboocoot wrote: »

That's exactly what we wear in Canada too! The polar bears think we're crazy of course ...

Moved here from Victoria, lived on a boat at WestBay Marina in Esquimalt, no shorts being worn there.

Cheers

Building new Off Grid Home in Panama

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