Gruntled

Thank you for all the replies everyone. I think I have decided what I will do with my power/irrigation needs.

I actually have 2 separate pieces of land I want to irrigate. The first will in future be a cashew farm and I only intend to irrigate it for the first 2 dry seasons to ensure I don't have any of the trees die when they are young. After that I shouldn't need to irrigate as they are hardy and should have no problem surviving a dry season.

The other piece will have 2 quite large fish ponds (approx. 1/2 rai each), to use as the water source. These ponds will be used to irrigate 3 or 4 rai through the dry season. The groundwater level is quite high in the area and other smaller ponds in adjacent fields never go dry during the dry season though their levels do drop a bit. I am not expecting any issues around water availability and I think the ponds will most likely recharge faster than I plan on drawing the water out anyhow. If they don't it would be easy for me to put a well in to supplement the recharge but hopefully I won't have to pump that much volume to maintain their water level. I do plan on stocking the ponds but I don't really plan on farming the fish commercially, that might change in the future but for now I don't think I will bother. 

After reading all the replies and doing some further reading I think I will likely go with a solar system on the 1st piece of land, it has no reasonable access to mains power so it would either be solar or a generator or possibly even running the belt drive pump I already have off of our old "rot thai". For a 2 year application the payback on solar isn't there but my plan would be to then relocate the system to the other piece of land. I am thinking of a .5 kw to 1 kw sized system which would meet my needs. I would want to keep it as simple as possible so I figure that means panels, a controller, a brushless dc pump and a battery (for the controller I am not planning to run anything at night). This decision is mostly for convenience as the "rot thai" option would basically be free but it means I would need to ride the dang thing 5-10 km every time I want to irrigate. The generator is another option as it would be a "nice to have" addition but to get on big enough and reliable enough isn't that cheap and I don't want to have to bother with another gas engine to maintain. I do kind of go back and forth on whether or not the generator would be a better option, as it would likely cost half what the solar system would cost, but then it would have fuel costs, maintenance costs and I think I just like the idea of using solar if possible.

On the other piece of land I think I will pay the money to bring in mains power. In the future I want to build a small shop on this piece of land and while the power requirements over time are not that much I will want to be able to run some intermittent higher draw items like an air compressor, a welder, etc. For the first 2 years I will use a simple ac pump for the irrigation and after that I will use the relocated solar system. I expect that the irrigation system will use the most power over time and since I will already have the solar system I may as well use it. While I am happy to save money, it isn't really the main driver. A big part of the decision is based on convenience and simplicity. I suppose I could put in a solar system with batteries and inverters I can't see how it would be cost effective and I really don't want to have a battery bank for anything other than the controller.

One final objective to all this is for me to learn a bit more about solar with the possible future goal of offsetting my air-conditioning costs with a non-export system or maybe even with a tariff export system if the tariffs are increased or the regulations are improved/simplified.

If anyone has any suggestion on how I can improve this plan please let me know. If there are any glaring poor choices or oversights on my part please feel free to point them out. Cheers!

4 minutes ago, Crossy said:

 

A small charge controller and minimal battery would let you run a baby inverter for fans and tool battery charging.

Is the battery a requirement for the charge controller to work properly? One other question, I have a 4th piece of land I will want to irrigate for one or 2 seasons. Is it possible to move the panels from farm to farm. I might be able to wrap them up pretty good but the roads are pretty bad so while they wouldn't get impacted they would get shaken.

I don't have any real requirements for flow rate or anything as this is a want to have rather than a need to have system. The total lift on the inlet side of the pump will only be 5-10 feet and less than that on the pressure side. I am thinking of a 1-2 hp pump 5,000-10,000 litres/hr would be fine. Rather than making things too complicated sticking with a straight DC pump system for irrigation might be the way to go.

Would it be possible to run a small inverter off such a system to run a fan or 2 and maybe charge the batteries on tools, lights or phones or should I be thinking of having a generator or other power source for that?

Ok, I think I get it. The panels simply charge to their rated voltage and without any load it is like an open circuit so no current flows and no heat is generated. I was thinking of them as though they were being charged by the sun like you would charge a battery until it over charges and explodes or something.

To answer your question, the application I am planning is detailed in my other post.

Thank you for the prompt reply.

A further question I forgot to mention in the OP. I presume that once panels are installed they will immediately begin generating potential, if they are disconnected while exposed to sunlight does this damage them? Cause them to get hot or anything?

For a bit of background, my wife and I have a few plots of farmland. There are 2 plots that we have robber trees on and when we first planted them we put in a well and ran a belt drive pump off our rod-thai walk behind tractor thingy for irrigation when the trees were small. We are in the process of buying another piece of land and will again be wanting to irrigate but in this case the irrigation will be much more regular, possibly daily during dry season. If possible I would like set up a simple off grid system to provide enough power to reliably run at a minimum a 1kW pump. The pump location would be about 400m from the nearest power supply so running a mains line into the pump is possible put it wouldn't be cheap at 2k baht per post or so, (I don't want to do the local standard practice of running the line in on bamboo posts). I would love to also have an inverted power supply at the pump location to run small electrical tools, fans, etc., but that is not deal breaker. I would like to be able to run a welder too but I think that might be unrealistic as that steps up the draw to almost 5 kw.

As far as I can see it I have 4 options. The first is to pay for the mains posts and set up and pay for the electricity forever. The second would be to run a generator and pay for fuel and maintenance on the generator. The third would be to put in an off grid solar system. The 4th would be to run the mains in and have an on grid solar system to reduce the power consumption. I am leaning to the off grid system as my peak power consumption would be during the hours of peak generation and even if the installation cost more than running a mains line (say 50kbaht or so) I would prefer so save the money on the electricity. One other thing is I would really like to avoid putting batteries in the system for a whole host of reason.

I am a reasonably capable DIY guy and did much of the wiring for my house but to be honest I don't know squat about setting up inverters/power controllers but am keen to learn.

So I am hoping for any suggestions or feedback about my plans as I am really starting at a low knowledge level.

Hi, I have looked through the forum and while the information here is very helpful, I have a few very basic questions that I can't get my head around.

The big one is if you are running an off grid system without batteries how do you manage the current. For example I can see how a controller/inverter can keep you at a fixed voltage but what does it do when current draw exceeds the power available? Does it just turn off if it can't maintain 220v? Also, how does the system manage excess production when you are producing more than the load? Does it just dump it to ground or something? Doesn't seem like a great idea to me.

Another lifetime ago running heavy DC mining trucks when you engaged the break retarders the system would a dump huge amount of energy into a bleed system that basically converted the energy to heat and blew it out of the truck with cooling motors. Do modern controller/inverters have the ability to do something like that? If so, how reliable/advisable is this kind of a set up. I hope I am not talking like too much of an idiot here but my biggest off grid concern at this point is not generating the power but rather how do I get rid of the excess when I have low or zero draw.

Thanks for the replies everyone. Getting the water tested seems a logical first step. Probably will go the treatment route since I have never seen deep water wells in our area as are common back in the west. All the wells in our area tap into surface groundwater. No idea if there is a subsurface aquifer or how deep it would be or of what quality.

Hi all, I am hoping for a bit of advice regarding a borehole issue I have.

At our home the water in our 10 m deep borehole is sufficient for volume and has only once in the past ever had a problem with running dry during a particularly prolonged dry spell a few years ago. Water volume and reliability is not the problem I am having. Water quality is the issue. The water stains things yellow and tends to build up some sort of tartar like plaque on the inside of fixtures and pipes. Also the direct pump discharge into our tank is quite silty as the tank needs annual clean outs despite having its outflow point about 60 cm above its base.

So what is my question you ask......well I want to know is... Would I be better off trying to drill a deep well to hit a deeper, cleaner aquifer or should I be looking into some sort of water treatment. To the best of my knowledge no one in the area has a deep well and I don't know anyone who has a treatment/filter setup. There is a reverse osmosis plant in town with a very elaborate filter system but I don't have any idea who installed it.

Thanks in advance!