Living offgrid with small solar system(s)

[George Harmony]

Then i continue with my rechargeable fan with also dc input and exhaust fans with buildin solarpanel as add-ons to my passive cooling.

About passive i was inspired by this info: https://m.youtube.com/watch?v=IvCI3Q_5A8Y

Some picts of my current situation:

[gk10002000]

Stateside I had a large class A (bus RV). It had an almost full size frige amd freezer that ran on propane (essentially a pilot light) and a little battery power. Likely an efficient home off grid solution.

Yes. I strongly suggest the OP look at using Propane to supplement the solar electric systems. Gosh, so many street vendors, small restaurants use propane it should be easy to go load up and re-fill in town every other month.

[IMHO]

You don't use step-downs or regulators - you use proper solar charge controllers that are designed for the job. Not only do they "step down" the voltage, they maintain the most efficient load on the panels to maximize PV efficiency, and use smart charging techniques (including scheduled over charge) to maximise battery life.

The cheap ones are essentially variable PWM regulators, the better ones implement MPPT technology.

There are several ways to implement tracking, but the gains vs costs are usually only worth it if the system is so large it's in the mega watt range. The extra 15-20% you can get from tracking can also just be made using 20% more PV panels and a good MPPT charger or inverter. In most domestic systems, and extra 20% PV is going to be a lot cheaper than a tracking system.

[Jing Joe]

Then i continue with my rechargeable fan with also dc input and exhaust fans with built in solar panel as add-ons to my passive cooling.

About passive i was inspired by this info: https://m.youtube.com/watch?v=IvCI3Q_5A8Y

Some picts of my current situation:

The guy in the URL seems to have conflicting and/or incomplete theories about cooling his round house. Beware?

He could have used the nighttime cooler winds to cool the building mass, and close them next the morning till the point of equilibrium during the hot day by choosing to open them or not, depending on how much the cool floor was going to contribute.

He rightly spoke about the cool floor and yet said the hot air could rise to the high domed ceiling. Maybe the hot air was really coming in that gap above the walls? What a waste of his cool floor source?

Wondering about the useful thermal mass in the outside walls and one interior wall that would hold the cool from night time, and yet hot breezes were also allowed to come in the windows.

Surely if the upper structure was sealed with a proper ceiling (not just high thatched) and better insulated like the esky ice boxes in our posts, could he control it better by using just this cool-floor source alone and mostly keep the windows shut at his choosing?

If its working for him now; great, but how much better could he have designed it for himself and others who might blindly follow him?

There seems many others interested in this subject who have uploaded You-Tube contributions. I'm yet to look.

Last night here was breeze-less so my two exhaust fans worked overtime to get the cooler outside air in, and then I shut the windows on the hot day.

[Muhendis]

Jing Joe, I've often considered using fans to bring in the cooler air at night. How well does it perform? I presume you have mosquito netting across it.

My house is more like a European house with cavity walls stuffed with polystyrene. It is cool in the hot sun and warmer at night. I briefly looked at the guy in the URL and switched off when I saw the roof. It's a wonderful breeding place for just about every insect that exists. The cool floor is OK but that's easily done with the building techniques here in Thailand. So I guess what I'm saying is what he's done is OK but nothing special.

[Muhendis]

IMHO is absolutely right about the advantages of MPPT and a purpose designed charge controller. Using the LM2577 module will give a constant voltage charge to the battery which is a time dependent way of charging the battery. The problem with that of course is there is no way of knowing whether the battery is fully charged, over charged or partially charged without monitoring regularly. Having a charge controller will automatically ensure correct charging. I'm not too sure about getting one small enough for a 7Ahr battery but I expect they are out there somewhere. Having said that they relative costs of the LM2577 and the battery may be significantly less than the cost of a decent charge controller so economically it could make sense to replace the battery more frequently.

Edited February 28, 2016 by Muhendis

[George Harmony]

The lm2577 works also like a dc-dc inverter. Even when the panel gives 4-5 volt output is constant at "up to you" , e.g. 14v.

I connected between the panel and chargrcontroller (simple pmw), so automatic cut off when fully charge. Different is when you for example use a lm2577 with small panel upto 15wp. No chargecontroller needed cause if you install it with output e.g.13.8 volt, no more charging when the battery reach 13.8

Cause the panel is small it will do no harm to the bat,perhaps getting a little bit warm. Handy if you daily have loads. No need chargecontroller. For example outside lamps with day/night sensor.

[George Harmony]

About above example lm2577. I think bat will not chargr anymore at 13.6v.

There is a member from myanmar who asked where one can buy dc water pumps.

Perhaps this is also handy. A tool for a bormachine. Use this with a 12v bormachine if you are offgrid and u have a waterpump

Two in one. You havr bormachine and a waterpump

Edited February 28, 2016 by George Harmony

[Jing Joe]

About above example lm2577. I think bat will not chargr anymore at 13.6v.

There is a member from myanmar who asked where one can buy dc water pumps.

Perhaps this is also handy. A tool for a bormachine. Use this with a 12v bormachine if you are offgrid and u have a waterpump

Two in one. You havr bormachine and a waterpump

C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_arrow-tech-waterpomp-gedreven-door-boormachine-vlo.jpg

What on earth is a bormachine George?

Did you read how satisfied I am with the brush-less, magnetically coupled, P.V. friendly water pumps?

Back in the early pages of this subject. From Topsflow pumps.

Now days you would surely think twice at any pump with a sealed bearing needing an external motor?

[Muhendis]

I agree Jing Joe. I use a tops flow pump running direct from a small PV to pump water around my hot water solar system. Its a stainless steel pump because of the high pressure (3bar +). I have had a bit of an issue with one but I wisely, as it turned out, bought some spares at the same time. I have just finished modifying the drive circuit for it by adding an LM2599 module so as to control it's speed a bit. The water gets even hotter now . I have also added an under voltage cut off so that if the sun is a bit shaded the motor stops. The motor won't start again 'til the PV voltage is higher than the cut off voltage. It's about one volt hysteresis. Some might say a bit of an unnecessary refinement but one of the problems with these pumps is that if the supply voltage to them is gradually increased, as for example when the sun is rising, then the motor won't necessarily start so my little refinement ensures that can't happen.

[Muhendis]

That external drive pump looks like something to which you might fit an electric drill or maybe I've got the scale wrong and it requires the power take off drive from the back of a tractor. George. Is a bormachine another word for electric drill?

[Naam]

About above example lm2577. I think bat will not chargr anymore at 13.6v.

There is a member from myanmar who asked where one can buy dc water pumps.

Perhaps this is also handy. A tool for a bormachine. Use this with a 12v bormachine if you are offgrid and u have a waterpump

Two in one. You havr bormachine and a waterpump

C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_arrow-tech-waterpomp-gedreven-door-boormachine-vlo.jpg

What on earth is a bormachine George?

Did you read how satisfied I am with the brush-less, magnetically coupled, P.V. friendly water pumps?

Back in the early pages of this subject. From Topsflow pumps.

Now days you would surely think twice at any pump with a sealed bearing needing an external motor?

Bohrmaschine = German word for:

[Naam]

That external drive pump looks like something to which you might fit an electric drill or maybe I've got the scale wrong and it requires the power take off drive from the back of a tractor. George. Is a bormachine another word for electric drill?

final proof that you are a true muhandis المهندس

[Jing Joe]

Jing Joe, I've often considered using fans to bring in the cooler air at night. How well does it perform? I presume you have mosquito netting across it.

Hi Muhendis,

The toilet fan has a 2m x 300mm chimney above on the roof with a china-mans hat at the top so when a breeze passes it, the shape draws air up.

If there's no breeze, the 240v fan mounted in the bottom of the chimney does the job but it doubles up for cooling during the night, all night. No mozzie net. They don't fly down it.

I check first the incoming air through just one partly-opened screened window, then turn the fan on and smile satisfied, then open the window/s further. Also smile when the the fan turning by its self when there is a good breeze.

Now that opens up a whole new subject of alternative energy using tall chimneys as thermal air turbines. But not today.

The second fan is hacked from a 240v mobile room evap. cooler mounted in a hole in the wall with brass mozzie mesh. It still has the three speed control, and wow that really gets a smile going.

Depending on the prevailing breeze and temp conditions; none, one or two fans are used and by morning, measuring the temp of the solid walls usually confirms that the inside is the same as outside. There is a fixed inside/outside digital readout.

So then all the windows are closed and is cool inside most of the day.

Not much heat builds up in our absence during the day (if I haven't paid attention to the above the night before), but on opening the windows, if there is no through-breeze , both fans give quick relief to freshen up the inside.

It's all second-nature now and "common alternative energy sense", so much so I had to stop and think about your Q .

Working in with nature has delightfully become thoroughly integrated. I'm living a life long dream.

Hope this helps someone.

[George Harmony]

Yeah...sorry.... Bormachine=electric drill. The above is a very handy tool if its difficult to buy/find a dc pump. So, if you have a electric drill this can perhaps also be a backup in case your pump goes kaput.

Just youtube for examples.

[George Harmony]

Here is an example.

https://m.youtube.com/watch?v=vvz3752M60s

[George Harmony]

Some picts that ive found and they called dessert passive cooling. Do you think that undergrounds pipes really help to cool a house? And how about if i also use fans to blow the air in thr pipe under the ground which ends above the ground. In combination with exhaust fans should in theory cools a room a little bit.. ?????

[Naam]

[Jing Joe]

I agree Jing Joe. I use a tops flow pump running direct from a small PV to pump water around my hot water solar system. Its a stainless steel pump because of the high pressure (3bar +). I have had a bit of an issue with one but I wisely, as it turned out, bought some spares at the same time. I have just finished modifying the drive circuit for it by adding an LM2599 module so as to control it's speed a bit. The water gets even hotter now . I have also added an under voltage cut off so that if the sun is a bit shaded the motor stops. The motor won't start again 'til the PV voltage is higher than the cut off voltage. It's about one volt hysteresis. Some might say a bit of an unnecessary refinement but one of the problems with these pumps is that if the supply voltage to them is gradually increased, as for example when the sun is rising, then the motor won't necessarily start so my little refinement ensures that can't happen.

Hi Muhendis. Perhaps you haven't seen their TOPSFLO catalogue of the "PV friendly" prefix letter added when ordering? Like a submersible prefix letter. There is virtually no extra cost from memory. Listening to mine start up slowly in the morning half-sun is a delight and also as the clouds come and go it runs nicely about 1/2 ? speed no problem. It pumps an 8 metre head and very roughly would take about an hour or two to pass about 300 litres at that head. I bought another pump ready for my concrete slab heating/cooling project that has max 11m + head capability, is a nominal 24v and "PV compatable" so on winters days will automatically run from two spare panels in series when the sun is shining. On summers nights to cool the slab it will run on a 24v DC power pack from my 240v inverter.

Re flow rate to slow the water down a bit so it gets hotter, I have used a small coin (the right size or made to fit), with a small hole drilled in the centre and simply put it in one of the water pipe connections. This was common practice. Was it 1/16 inch or 1/8 inch? Cant remember.

[Jing Joe]

Some picts that ive found and they called dessert passive cooling. Do you think that undergrounds pipes really help to cool a house? And how about if i also use fans to blow the air in thr pipe under the ground which ends above the ground. In combination with exhaust fans should in theory cools a room a little bit.. ?????

Hi George, Underground housing is a subject very dear to me, and so could the u/g pipe system you are looking at. Have you experienced that cool U/G feeling yet? Wow.

How strong can the silver flexible air conditioning ducting get folks? Would it resist not just a bit of earth pressure but corrosion? What if there was a very basis u/g irrigation pipe or two to increase the heat conductivity of the earth around the tubes? Deep enough shouldn't it stay moist for a while? What about economical versions of PVC 90mm (or larger) pipes?

Re fans George, unless you use a 240 v without brushes, do check out for the latest in brushless DC fans. Some have ball bearings, better still ceramic bearings and even better now; magnetic levitation bearings. The 90mm size pipes sound nicely matched to these fans that can be commonly up to 125mm I think. Looking around might find even bigger fans to match the air/con duct sizes?

If you happen mount the fan/s at the finishing end of the tube, (inside the house, for convenience), keep in mind that propeller type fans are better at blowing than sucking.

P.S. surely a per-requisite to this project would be to efficiently make a 20mm? dia. test hole into the ground at your choice of depth and insert/lower a temp probe from a cheap indoor/outdoor temp device into a protective 1/2 inch poly or hose pipe. Don't let the probe extend past the end for easy retrieval. Back-fill outside this pipe with sand? and monitor the temps at that depth. The deeper the cooler? Guessing 800mm to start? Google it. and more constant throughout 24 hrs? Even add some water to assimilate the probe to its surrounds at the bottom? Try again deeper if necessary. Imaging if you struck the permafrost we hear about? WOW. Wrong country, wrong application sorry.

Edited February 29, 2016 by Jing Joe

[Muhendis]

One of the ways to cool a house which has been tried and tested, is to make use of a radiator from an old AC unit or a heat exchanger from an old fridge (or even making it yourself). Pump cold water into it and blow air through it. The cold water in the pipes will cool the air. The water can come from your well or bore hole where it is really cold and be returned after passing through your cooler. The guys in this link use a cold box full of icy water but I think that method a bit power hungry needing, as it does, ice from somewhere. A better way is to use the cold water as it naturally is from your underground source. It would need some plumbing skills and a lot of enthusiasm.

http://www.instructables.com/id/Hollis-homemade-AC/

[Jing Joe]

One of the ways to cool a house which has been tried and tested, is to make use of a radiator from an old AC unit or a heat exchanger from an old fridge (or even making it yourself). Pump cold water into it and blow air through it. The cold water in the pipes will cool the air. The water can come from your well or bore hole where it is really cold and be returned after passing through your cooler. The guys in this link use a cold box full of icy water but I think that method a bit power hungry needing, as it does, ice from somewhere. A better way is to use the cold water as it naturally is from your underground source. It would need some plumbing skills and a lot of enthusiasm.

http://www.instructables.com/id/Hollis-homemade-AC/

Agree, mostly on other ways to harvest cool energy below surface.

Rather like the steam radiators in hospitals and houses.

How about having a radiator (instead of pipes) in the well, and one in the house like you suggested?

Copper pipes or a radiator in a cool well would be great even with their relatively small surface area "engaging" the water. That's if you are lucky re having a well. For me, the ice bucket idea in the video sucks.

Blowing air through plain earth in larger tubes could be better than pumping water through smaller dia. copper pipe? (no wells)

How about introducing air bubbles into an upward sloping water pipe to move the water if water pumps were a problem.

Just thinking. Its been done in other applications.

Edited February 29, 2016 by Jing Joe

[Muhendis]

One of the ways to cool a house which has been tried and tested, is to make use of a radiator from an old AC unit or a heat exchanger from an old fridge (or even making it yourself). Pump cold water into it and blow air through it. The cold water in the pipes will cool the air. The water can come from your well or bore hole where it is really cold and be returned after passing through your cooler. The guys in this link use a cold box full of icy water but I think that method a bit power hungry needing, as it does, ice from somewhere. A better way is to use the cold water as it naturally is from your underground source. It would need some plumbing skills and a lot of enthusiasm.

http://www.instructables.com/id/Hollis-homemade-AC/

How about having a radiator (instead of pipes) in the well, and one in the house like you suggested?

Copper pipes or a radiator in a cool well would be great even with the relatively small surface area "engaging" the water. That's if you are lucky re having a well.

This is a good idea but you would need to add an expansion tank into the circuit and some consideration about the minerals commonly found in deep borehole water if that's the chosen source. A shallow well would have less minerals but would be prone to drying up.

[BKKdreaming]

The off road racers here used a "cool suit" when they were out in the desert ,

here is the Google image link to give you some ideas....

https://www.google.com/search?q=racing+cool+suit&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiJzrO_8ZvLAhVV7mMKHflbBGgQsAQIaw&biw=1366&bih=623

Now think about a nice comfy recliner with a "cool suit" lining , your feet up and a cold one

Why cool down the whole room when you only need to cool your "personal" space

and here is a cooled seat

https://www.google.com/search?q=racing+cool+suit&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiJzrO_8ZvLAhVV7mMKHflbBGgQsAQIaw&biw=1366&bih=623

Edited February 29, 2016 by BKKdreaming

[George Harmony]

Excellent replies about cooling,wow.

Just curieus, @jingjoe,are you the same person whom i had talked about solar power somewhere else few years ago when i was running businesses in Udon? If so, if remember well you also recently have build a house in thailand. What kind of cooling strategies did you use for that house. Is it what you described above??

[Jing Joe]

One of the ways to cool a house which has been tried and tested, is to make use of a radiator from an old AC unit or a heat exchanger from an old fridge (or even making it yourself). Pump cold water into it and blow air through it. The cold water in the pipes will cool the air. The water can come from your well or bore hole where it is really cold and be returned after passing through your cooler. The guys in this link use a cold box full of icy water but I think that method a bit power hungry needing, as it does, ice from somewhere. A better way is to use the cold water as it naturally is from your underground source. It would need some plumbing skills and a lot of enthusiasm.

http://www.instructables.com/id/Hollis-homemade-AC/

How about having a radiator (instead of pipes) in the well, and one in the house like you suggested?

Copper pipes or a radiator in a cool well would be great even with the relatively small surface area "engaging" the water. That's if you are lucky re having a well.

This is a good idea but you would need to add an expansion tank into the circuit and some consideration about the minerals commonly found in deep borehole water if that's the chosen source. A shallow well would have less minerals but would be prone to drying up.

I'm confused M. If two radiators are involved when meaning a closed circuit system as per your suggested expansion tank (which could be easy) so would you be concerned about the pipes/radiator external exposure to the mineralised water? Is this what you mean? I could well understand and never contemplate an open circuit because of minerals deposits internally in our pipes and creating problems, most likely calcium.

Closed circuit return system also involves a convenient gravity consideration in that less energy is needed to move it because of the effective balance of weights in the supply and return route..

An open system sort of means energy pumping from the bottom of the well through the absorber/collector, up to the radiator at surface and dumping the water back to the well. No way Hosea.

[Jing Joe]

Excellent replies about cooling,wow.

Just curious, @jingjoe,are you the same person whom i had talked about solar power somewhere else few years ago when i was running businesses in Udon? If so, if remember well you also recently have build a house in Thailand. What kind of cooling strategies did you use for that house. Is it what you described above??

Sure it's a small world George, but I'd hate to have to paint it.

No we have never met but it sure is a pleasure to do so now this way.

My Thai wife has twisted my arm to build in LOS and maybe live there.

If ever, it would only be way up North where it is cooler.

Only been a tourist 3 times.

[Jing Joe]

Some picts that ive found and they called dessert passive cooling. Do you think that undergrounds pipes really help to cool a house? And how about if i also use fans to blow the air in thr pipe under the ground which ends above the ground. In combination with exhaust fans should in theory cools a room a little bit.. ?????

Hi George, Underground housing is a subject very dear to me, and so could the u/g pipe system you are looking at. Have you experienced that cool U/G feeling yet? Wow.

How strong can the silver flexible air conditioning ducting get folks? EDIT, Huge surface area. Would it resist not just a bit of earth pressure but corrosion? What if there was a very basis u/g irrigation pipe or two to increase the heat conductivity of the earth around the tubes? Deep enough shouldn't it stay moist for a while? What about economical versions of PVC 90mm (or larger) pipes?

Re fans George, unless you use a 240 v without brushes, do check out for the latest in brushless DC fans. Some have ball bearings, better still ceramic bearings and even better now; magnetic levitation bearings. The 90mm size pipes sound nicely matched to these fans that can be commonly up to 125mm I think. Looking around might find even bigger fans to match the air/con duct sizes?

If you happen mount the fan/s at the finishing end of the tube, (inside the house, for convenience), keep in mind that propeller type fans are better at blowing than sucking.

P.S. surely a per-requisite to this project would be to efficiently make a 20mm? dia. test hole into the ground at your choice of depth and insert/lower a temp probe from a cheap indoor/outdoor temp device into a protective 1/2 inch poly or hose pipe. Don't let the probe extend past the end for easy retrieval. Back-fill outside this pipe with sand? and monitor the temps at that depth. The deeper the cooler? Guessing 800mm to start? Google it. and more constant throughout 24 hrs? Even add some water to assimilate the probe to its surrounds at the bottom? Try again deeper if necessary. Imaging if you struck the permafrost we hear about? WOW. Wrong country, wrong application sorry.

[Muhendis]

Jing Joe. The minerals commonly found in my particular bore hole are magnesium and iron which are quite corrosive to copper (probably aluminium also) It would be safer, although more expensive, to use stainless where the pipes are in contact with the water/minerals. I'm no chemist but I think there would be a corrosive reaction against most metals.

[Jing Joe]

Jing Joe. The minerals commonly found in my particular bore hole are magnesium and iron which are quite corrosive to copper (probably aluminium also) It would be safer, although more expensive, to use stainless where the pipes are in contact with the water/minerals. I'm no chemist but I think there would be a corrosive reaction against most metals.

Ah Ha thank you M.

So a bundled up 50 metre roll/coil of 1/2 inch (or 3/4 inch better) black poly pipe could do the trick down the well?

And the up and down pipes could be part of the roll too. No joins.

But still have a closed circuit of clean water circulating. The expansion chamber could be as simple as an open cylindrical shape reservoir just needing to keep an eye on and with high humidity, not much evaporation might occur?

A upper power Tops Flow pump would be just the go? Black poly pipe is very shiny inside with low resistance.

The "radiator" in the house could be another roll of the same black poly pipe too. With spacers to keep open for the largest surface area, hide it in a nice box with a fan assisted breeze in and out of the box? KISS. Keep it simple.

Low pressure Black poly poly irrigation pipe is usually very U.V. resistant, relatively thin walled and much cheaper than town pressure pipe.

Edited February 29, 2016 by Jing Joe