Solar Power Off Grid - Help w/ excess power

I'm the stateside point of contact for some friends in Haiti. They are off-grid. (waaaaaay off!) We have intermittent contact as they are able.

They've got a pretty nice solar setup, but are 'panel heavy'. Ideas from people w/ experience on what to do with the excess power? They are hitting 100% charge by noon each day. And that's having gone through bulk, absorb, and float to get there.

Adding batteries is not an option. They would cost too much, and they have no need for extra loads at sundown/evening/night.

Electrical water heating is not a big concern, because they have no running water. Most useful thing they need water-wise is more of it, and CLEAN water.

Panel output is around 4kw. Battery bank is around 900AH @ 48v (single string). Inverter is a magnum4448. Midnight solar charge controller. Other assorted stuff... temp monitors, bmk SOC meter, etc.

How about donating the excess panels to a community that that doesn't have basics like lighting ?

You mentioned the need for clean water, Send the extra power to a UV light water purifier or rig a UV light in water storage tank

MikeAusC said:

How about donating the excess panels to a community that that doesn't have basics like lighting ?

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Panels are only usable during the day. We are dealing with people (community) that don't have shoes. They would not know what to do with panels (and related) materials if you gave them a tractor-trailer load.

CMAG said:

You mentioned the need for clean water, Send the extra power to a UV light water purifier or rig a UV light in water storage tank

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First, they need water (in any form) for this to work. Only water source I know of is a local river. Too far to pump it though. Besides, people would steal the pipe/wire/etc.

Only answer may be to do nothing.

Just a thought, but could they run a dehumidifier on the excess power?

I have to empty mine everyday, and Haiti is a lot more humid than my house. I pull a couple gallons out every day.

I am just talking about an experiment here, but find a small efficient dehumidifier and send it to them. See how much water they can pull out of it.

If it works then you can start looking into a more sophisticated set up that will run more efficiently.

I would think rain water collection would serve their water needs, but I guess it doesn't.

turbodog said:

First, they need water (in any form) for this to work. Only water source I know of is a local river. Too far to pump it though. Besides, people would steal the pipe/wire/etc.

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No need for plumbing if they carry buckets of water back to camp a UV light will kill any parasites and other nasty things google steripen a pocket version of what i am saying you put the tip with a UV light in a glass of water turn on and wait 90 seconds. a larger solar powered UV bulb could be simple as mounted to the inside cover of 5 gall pail or whatever they use ( burning there excess power) would save them from boiling water to kill germs
Just a thought that is why I said "or rig a UV light in storage tank"

bfayer said:

Just a thought, but could they run a dehumidifier on the excess power?

I have to empty mine everyday, and Haiti is a lot more humid than my house. I pull a couple gallons out every day.

I am just talking about an experiment here, but find a small efficient dehumidifier and send it to them. See how much water they can pull out of it.

If it works then you can start looking into a more sophisticated set up that will run more efficiently.

I would think rain water collection would serve their water needs, but I guess it doesn't.

Click to expand...

If you are talking about using it to generate drinking water, that's a new idea we had not though of.

If it's to dry out the house... sorry. The house is open air. The sun they get makes it waaaay to hot to close up. Even if you had grid power, I don't think you could cool that house.

CMAG said:

No need for plumbing if they carry buckets of water back to camp a UV light will kill any parasites and other nasty things google steripen a pocket version of what i am saying you put the tip with a UV light in a glass of water turn on and wait 90 seconds. a larger solar powered UV bulb could be simple as mounted to the inside cover of 5 gall pail or whatever they use ( burning there excess power) would save them from boiling water to kill germs
Just a thought that is why I said "or rig a UV light in storage tank"

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Missed that, but the UV killers I have don't work well in nasty (brown/dark/etc) water. And that's what they have there...

bfayer :thumbsup: good thinking drink the humidity hit it w/uv light to be safe

turbodog said:

Missed that, but the UV killers I have don't work well in nasty (brown/dark/etc) water. And that's what they have there...

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water just has to be strained thru a old T shirt or sock first

worst case if they still have power to burn run a bug zapper

CMAG said:

worst case if they still have power to burn run a bug zapper

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Spare power disappears @ dark. After batteries are charged, any power not used is lost. So from noon till dark... there's a very significant amount of power available, but no good thing to use it on.

The thing with solar is you think you have too much till you don't, and when you don't is when you really need it. They have a 40KW battery bank and a 4KW panel bank. It really comes down to what their drawn down is per day. In some ways they may have both too much panel and battery. There are certainly advantages of having lots of battery and little daily draw down ... unless the batteries are hot in which case they are going to die quick anyway.


If you have excess power you can:

- Move something
- Pump something
- Electrify something


1) Pumping for a community available well
2) Running a community water purifying system
3) Providing charging capacity for their neighbors (phones, small batteries, etc.)
4) If you have a pump, the you can consider swamp coolers.

Where in Haiti are they? I have friends doing medical work down there.

Semiman

There is a useful short article on wikipedia under the search title "atmospheric water generator" and some links at the bottom of the page. Some versions are based on cooling condensation (like a dehumidifyer) and some on compression.

If they really have that much excess power, perhaps they can conider to start a light manufacturing process of some kind, such as a small cnc machine shop or wood working operation.

It might be possible for them to drill a fresh water well and pump water for farm animal use into a small pond ?

If I remember correctly, Haiti is one of the original locations where mosquitos were native. If excess electricity is available, perhaps setup some kind of electrified wire grid to keep out insect pests, both for the garden and for lowering the rate of infection.

SemiMan said:

The thing with solar is you think you have too much till you don't, and when you don't is when you really need it. They have a 40KW battery bank and a 4KW panel bank. It really comes down to what their drawn down is per day. In some ways they may have both too much panel and battery. There are certainly advantages of having lots of battery and little daily draw down ... unless the batteries are hot in which case they are going to die quick anyway.


If you have excess power you can:

- Move something
- Pump something
- Electrify something


1) Pumping for a community available well
2) Running a community water purifying system
3) Providing charging capacity for their neighbors (phones, small batteries, etc.)
4) If you have a pump, the you can consider swamp coolers.

Where in Haiti are they? I have friends doing medical work down there.

Semiman

Click to expand...

Camp Coq

No community wells. They already charge many many cell phones.

Their draw down is ~15% a day.

They have 3 honda inverter generators as backup and for portable power for construction projects.

Batteries are in a purpose-built outbuilding and are around 80-82F or so.

Do they have a well? Any idea what the water temperature is?

If they could cool the batteries, they will last a lot longer. That is warm enough, especially with charging heat, to shorten the life. I am not aware of any small variable speed air conditioners, but if there was one, cooling the battery room would be a good use of excess power.

Charging battery powered lanterns (In addition to the cell phones).

Another cool idea, budget dependent, would be a hydrogen generation system to be used for cooking gas, etc.

Camp Coq is near a river so charging a very low cost electric vehicle for daily water runs if there is no well could be a priority in conjunction with the ideas above for purification.

Semiman

Do they have some form of reliable transportation? If not, here's an idea. Buy a few electric bicycles, and use the excess solar power to charge them during the day. You could use the bikes to bring water back from the river, bring in supplies, whatever. E-bikes aren't all that expensive. And if you buy a decent one, they're pretty reliable.

turbodog said:

If you are talking about using it to generate drinking water, that's a new idea we had not though of.

If it's to dry out the house... sorry. The house is open air. The sun they get makes it waaaay to hot to close up. Even if you had grid power, I don't think you could cool that house.

Click to expand...

No not drying out the house

Pulling water out of a continuous supply of humid air. The warmer and the more humid air the better.

A dehumidifier is just a small portable air conditioner. The refrigerant cools a coil, and the fan blows the hot humid air over the cold coil. A bucket catches the condensate (fresh water).

Not the most efficient, but if there is excess power, why not?