Time for solar-pumped water

[chatcher]

This is the year I'm jumping into solar energy. It will be a learning process.

I have two projects on the drawing board, one of which isn't very "tractor" intensive, but the other will have enough seat time to qualify.

The first is to provide water to my home during an electrical outage. I currently have a fairly shallow well with a 240 VAC jet pump and pressure tank which is dependent on grid power. I will be changing to a Grundfos SQFlex submersible pump which runs on anything from 30 to 300 VDC or 90 to 240 VAC. The plan is to run it from a 48-volt bank of batteries charged by solar (PV) panels, with the ability to switch it back to AC if the battery system fails. The pump is pretty expensive compared to an AC submersible, but it is supposed to be very efficient and long lasting. The tractor part of this project will be limited to digging post holes for the homemade solar panel mount. I shouldn't need to do any digging for water lines since I plan to run water through one of the existing jet pump lines and power wiring through the other.

The second project is to provide water to my garden from a nearby pond. I'll use a solar panel for this, too, since the greatest need for water will be on clear, sunny, summer days. I don't plan to use a battery for this, just one 12 VDC PV panel and an RV-type diaphragm water pump. And a linear current booster in between to help start the pump under load. I am not sure what I will do with the water once pumped, I actually have two plans. I have a 100-gallon bladder-type pressure tank left over from a previous project years ago. If the bladder is still good, I'll pump into it during the day and have 100 gallons of water under pressure whenever I need it. If that doesn't work out, I'll pump into 55-gallon drums in the loft of the barn near the garden and use gravity for watering. For this project I'll have to trench between the pond and the garden/barn area and dig a hole for the solar panel mounting post.

I could have run electricity to the garden, or water from the house for that matter, but the idea of freedom from the grid appeals to me.

I'd be interested in any tips from anyone familiar with these things, especially on constructing solar panel mounting arrangements that won't blow away.

 

[Soundguy]

I hate to cast any stones.. but.. maintaining a battery bank as a 'what-iff' battery backup, will be expensive... batteries go fallow when not used.. and I think you will find that you may not get a good return on battery service life vs cost, plus the cost of the new expensive pump, plus the cost of the solar panels. It mightbe a nice 'long term' idea for an 'EOTWAWKI' scenerio.. but in common practice.. not great unless you are ready to go solar whole hog.. house and all. ( when fuel cell technology comes out wide spread.. solar will become viable... )

on your panel powering a pump.. if you are pumping up a pressurized tank.. I'd hate to see the cost of the solar cell that would power that...

If your well is shallow enough for a hand pump.. I'd invest my money into one of those with a bucket over it for use when needed, and then buy a pto or stand-alone gen for my tractor to run everything else..

soundguy

If you have a pond.. what about a windmill pump?

 

[chatcher]

I hate to cast any stones.. but..

Cast away, please - I'd rather debug here than under the house.

batteries go fallow when not used.. and I think you will find that you may not get a good return on battery service life vs cost, plus the cost of the new expensive pump, plus the cost of the solar panels..

The batteries will be charged daily, or at least on sunny days. I hear you on the cost. Definitely the cheapest way to pump water is to hook up to the grid. But in an emergency the grid isn't there, so from a practical standpoint, since there is no high place for me to store water, it's either batteries or a generator for backup. A generator and fuel storage isn't cheap, either, and I'm more confident in the long term availability of sunshine than reasonably priced fuel. My first set of batteries are "free", so proving the concept won't be as costly as it could be, and the new pump will run on grid power if necessary.

on your panel powering a pump.. if you are pumping up a pressurized tank.. I'd hate to see the cost of the solar cell that would power that...

An RV-type diaphragm pump ($50 or so plus $100 for an electronic current booster or MPPT) should give me 45 psig, about 1 gpm, under 5 amps (12 vdc). I'm going to try a single 62-watt panel (about $300) and double up if I absolutely have to. That should be enough water to fill whatever storage arrangement I come up with on an average sunny growing season day.

If your well is shallow enough for a hand pump.. I'd invest my money into one of those with a bucket over it for use when needed, and then buy a pto or stand-alone gen for my tractor to run everything else..

For the house, the object is to keep the running water, uh, running. After spending the money on solar equipment, I don't want to have to tell Mama she has to pump water for her bath!

If you have a pond.. what about a windmill pump?

If I had some high ground for a water storage tank I'd consider that, although I don't usually have much wind, and the windmill wouldn't be cheap, either.

Good points, but you haven't quite talked me out of solar yet...

As far as a whole house solar system, I'm getting my feet wet. If the house water system works as planned I may add an inverter to run a few other things, which would probably lead to more panels, which would lead to more batteries... I'm not ready to make that commitment just yet.

 

[Jimbrown]

Ok I have a 6 SQF-2 pump running on solar power. It pumps 4 gallons a minute most of the time running at 48v 240 watts of panels. It works great with no batteries. Provided you pump in to a storage tank and not a pressure tank. I highly reccommend that you not try to use the Grunflos pump to fill pressure tanks. You need to pump into a storage tank and then use a seperate pump to pressurise with. I have several neighbors that tried that and all found that it did not work well and went to storage tanks and seperate pumps tp pressurise with . My system pumps into an 1800 gallon storage tank and then i use a shure flow 12 folt pump to pressurise my pressure tanks. The pressure system is 4 40 watt panles charging two golf cart batteries. The shure flow pump will pressurise 45 lbs OK. I use a regular pressure switch as opposed to the built in switch that comes with the shure flow pumps. My system has been running like that for 5 years. I pump from a 280 ft deep well with water level at about 100ft the pump is set at 140 ft.

As far as the pond pump I don't do that but my experience is that a one single panel (unless it is a really big one ) will not run the shur flow pumps. You need 5 amps or better to run the pump. You would/could use a single panel and one deep cycle battery for that purpose provided you did not pump all day and gave the battery time to recharge part of the day.

I do not know where you ae getting your prices But my well pump was $2700 pump, controller, wire, and pipe, installed. Did not include panels which I already owned.

 

[john_bud]

Rob (3RRL) has a pretty good write up on solar as his new house is off grid.

I think the solar was about the same cost as getting grid power at the wrong end of $100,000. But that's from my porus memory, so who knows ?

jb

 

[jimmer2880]

Rob (3RRL) has a pretty good write up on solar as his new house is off grid.

I think the solar was about the same cost as getting grid power at the wrong end of $100,000. But that's from my porus memory, so who knows ?

jb

Wow... that sounds like quite a system. I read in a magazine (popular mechanics?) about someone living off the grid in VT because the cost of running power to their place was too expensive. They still ended up running Generators part of the time, but learned a ton.

It would be interesting to read 3RRL's write-up.

 

[RalphVa]

I'd love to have a solar powered pump from a more shallow well down below (creek area is 100" below the house here). A submerged solar-powered pump would give you less trouble than your present jet pump. Just run it every once in a while to keep things going. You might need a battery to keep an even power input to the pump. I run my electric fence on a little 5 watt solar panel. All I did was slap the solar panel in place and connected it directly to the 12v battery that I was using (and having to recharge about once/month) before. In the winter, I bring the panel up and mount it in front of my carriage house to power a battery charger and inside light. Just took it down below again a few days ago. It's just mounted on a crooked pole that leans it at about 45 degree angle to the sun and leaning directly south. On the carriage house, I just made a little wooden bracket that I screw it to there. It's, of course, a smaller panel that what you likely need for your pump.

Ralph

 

[chatcher]

Ok I have a 6 SQF-2 pump running on solar power...highly reccommend that you not try to use the Grunflos pump to fill pressure tanks...several neighbors that tried that and all found that it did not work well...I pump from a 280 ft deep well with water level at about 100ft...

...my experience is that a one single panel (unless it is a really big one ) will not run the shur flow pumps. You need 5 amps or better to run the pump...

...my well pump was $2700 pump, controller, wire, and pipe, installed...

Good to hear from someone with a Grundfos helical pump installed and working. As far as the pressure tank goes, my well is a lot more shallow than yours, so I think I will have more pressure. Looking at the pump curves for your 6 SQF-2, at 240 watts and 4 gpm you should have about 150 ft discharge head, or a little under 20 psig after your 100 foot lift and pipe losses. The same pump at the same power in my application should give me over 50 psig, so I hope to not need the booster pump. I should know very soon, I will be installing the pump in the well shortly using the existing AC power source and in addition to learning whether or not it can handle the pressure tank setup I can read the power it's using in watts right off the control box panel.

I paid $1700 for an 11 SQF-2 pump, CU-200 control box, wire splice kit, and shipping. No wire pipe or labor included!

For the garden I shied away from the Shurflo pump for the exact reason you said - by using a smaller (and cheaper) pump I can hopefully get by with less panel, and the slower flow rate shouldn't hurt me given the relatively small amount of water I am able to store. If I were depending on it to provide water for my shower I wouldn't be so cheap!

...A submerged solar-powered pump would give you less trouble than your present jet pump...You might need a battery to keep an even power input to the pump...

One of the reasons I'm doing this now is that my jet pump is just about worn out. The reason I need the batteries is that I have no way to store enough water under pressure to get me through the night (and cloudy days). I would love to use gravity to store the energy but in my situation it isn't an option. The ideal situation would be to pump water uphill while the sun shines, and use the water 24x7, no batteries required.

 

[Jimbrown]

Some things to consider. The pump will not start if there is not enough current to run it at 500rpm or better. For my pump that is about 100watts. It will pump at about 80 or 90 but normally is running at about 180 watts. My pipe and wire cost was $432. This pump I have on 1 1/4 PVC. My last pump was a Dankoff it ran for 6 years. I had in on black plastic pipe and installed it myself. Self installation is not difficult.

 

[saltman]

I think it's great your going solar and will be off the grid for well power.

My new house will be totally solar with the exception of my well, simply because my well is away from the home and is 700 feet deep. I will use my porpane generator for well service.

I am surprised at some of the costs given for Solar Power, I currently have a 1,000.00 system that powers my small cabin and expect to spend no more than 15,000.00 on the system for my home. It's just two people in my household but currently on the grid and a 1,500 square foot 50 year old house I use only 429 KWH a month. So in a new home with tons of insulation, propane appliances and a lot of natural light I plan on getting by with a 4.5KW system. I purchased my solar stuff so far from Backwoods Solar Electric Systems they all live off grid and have good advice.

I think you will find that it doesn't take that much water pressure to fill a pressure tank. My well pump only is rated at 5gpm and it has no problem filling my 40 gallon pressure tank. Now that I have the 10,000 gallon tank at 100ft I no longer need the pressure tank but it worked great for almost two years putting out over 60lbs of pressure.

A inexpensive low energy pump for your garden can be found at WalMart the Attwood bilge pumps put out good pressure and don't cost more than 30.00 bucks. They are designed for a 12 vold stystem so no inverter or even a battery would be required as long as the sun is shining.

Good Luck

Derik

 

[Soundguy]

Chatcher... good luck with whatever you do..

With the $$ #'s being quoted here, and some quick math.. I'm having a hard time seeing how any of it is cheape rthan a full standby gen on diesel or propane with an automatic switch.

Sure.. you eventually run out of fuel.. and the sun will shine forever.. but... the upfront startup costs seem to be about 4x over a standby system.. plus the maintenance costs I'm 'guessing' about re: batteries, pump.. etc.. would likely offset fuel storage for -many- years.

One really bad storm and thousands of dollars of solar cells may be toast..... then you'd be SOL..

Still... If you7 are inclined to go for it.. do it. No one ever gets anywhere by not taking chances... Solar technology is a great idea.... as soon as battery technology catches up it will be a good combo.. good for you for being brave enough to stay on the edge... I wish all you off-grid guys well.

soundguy

 

[chatcher]

...The pump will not start if there is not enough current to run it at 500rpm or better...

That's a consideration. I think the batteries will take care of the current needed to start my Grundfos pump, although it does have some internal electronics (maximum power point type circuitry) so that it can be used in a batteryless design. The garden pump will need a current booster for morning startup and I think I found one that will work - a Solar Converters, Inc. PPT 12/24-7V.

...I am surprised at some of the costs given for Solar Power, I currently have a 1,000.00 system that powers my small cabin and expect to spend no more than 15,000.00 on the system for my home...
...I think you will find that it doesn't take that much water pressure to fill a pressure tank...Now that I have the 10,000 gallon tank at 100ft I no longer need the pressure tank...

...A inexpensive low energy pump for your garden can be found at WalMart the Attwood bilge pumps put out good pressure and don't cost more than 30.00 bucks. They are designed for a 12 vold stystem so no inverter or even a battery would be required as long as the sun is shining...

I'm rapidly learning that solar power is not really a replacement for grid power the way we have become accustomed to using grid power. In other words, my home has 200-amp service, electric heat pump with electric auxiliary heat, electric well pump, electric water heater, electric clothes dryer, refrigerator, freezer, and all the other energy hogs so common throughout suburban and rural America. A solar system that would handle all that would be obscene. But along with more sensible home design and energy management, it does allow you to do some pretty amazing things.

I'll check the bilge pump out.

 

[chatcher]

...With the $$ #'s being quoted here, and some quick math.. I'm having a hard time seeing how any of it is cheape rthan a full standby gen on diesel or propane with an automatic switch...

You're right it is more expensive up front, and maybe even over the long term, depending on whether or not the prices of oil and propane continue to rise. And a generator would allow us to pretty much go about our normal electricity usage where solar will be more limited.

But it's clean, quiet, odor-free, and just plain more appealing to me than a generator. I know oil had to be used and pollution had to be generated to produce all these neat solar toys, so I don't pretend it is as beneficial to the planet as some think. Anyway I've committed to at least trying it (with a "Plan B" every step of the way).

 

[denmansoft]

Why not just use a battery instead of a current booster?
Small 12V SLA battery will handle current surges of pump starting.
I've been paying $15 for 12V 7Ah

 

[chatcher]

Why not just use a battery instead of a current booster?
Small 12V SLA battery will handle current surges of pump starting.
I've been paying $15 for 12V 7Ah

The reason for choosing a current booster instead of a battery for the garden system is that the battery would completely discharge when the sun sets, stay drained overnight, and only begin to recharge in the morning after sunrise. Batteries typically don't last very long when treated that way. The current booster will allow the pump to start when the panel voltage comes up each morning, and the pump will run only as long as the panel is producing sufficient power.

My house system is pressurized and the pump shuts off once the tank is full, so the batteries there will hopefully never see a very deep discharge. The panels and batteries for the house will be sized to produce and store enough energy during one sunny winter day for several days of water use, while the panels for the garden will be sized to run the pump only while the summer sun shines (the garden should not need watering during winter or on cloudy/rainy days).

 

[RonMar]

House System:
How far do you have to run wires from Battery bank to pump?

What type and size of battery are you considering and what wattage of panels?

As I am sure you are aware, DC dosn't travel well. Would it perhaps be more cost effective to run a more conventional 240V AC well pump and use an inverter on your battery bank? This would allow you some added flexibility with the installation location of the panel/battery bank.



Garden system:

I am curious about operation. Will it run all the time sun is available?
What happens when the storage tanks you talked about are full? Is there some type of pressure switch/controller involved?

 

[Soundguy]

The ineficience in the inverter would be a furthere kink in the system. At best.. you see 90% efficient inverters.. that's just another 10% energy loss to factor in to an already borderline powerthirsty system that is off the grid. Heavy copepr will offset the power drop.. higher dc transmission voltage will too.. all with a co$t though..

soundguy

 

[RonMar]

That is why I said more cost effective, not more efficient. With the cost of copper these days to feed a current hungry device such as a pump, and with the losses in moveing DC any distance, a 10-15% inverter loss might be on par with the efficiency of his planned DC setup at far less cost in materials. It also opens the door to far less expensive AC pumps that still meet his need to revert to commercial AC or generator.

If you are only paying 1/4-1/10 the cost for the pump, that is more capital available for more solar panels, or higher capacity batteries, or just plain lowers the bottom line cost...

 

[chatcher]

House System:
How far do you have to run wires from Battery bank to pump?

What type and size of battery are you considering and what wattage of panels?

As I am sure you are aware, DC dosn't travel well.

Including the depth of the well, the distance from batteries to pump will be around 45 feet. At about six amps even using 12ga wire I shouldn't lose too much of the 48 volts battery voltage. I'm starting out with 340 watts of panels. The batteries I will be testing with are 12vdc AGM telecom batteries, and I have 8 of them. They cost me nothing (and may not be worth much more than that). Eventually I would probably use 8 6v golf-cart batteries, unless I expand the size of the system to add an inverter (and more panels of course).

Would it perhaps be more cost effective to run a more conventional 240V AC well pump and use an inverter on your battery bank? This would allow you some added flexibility with the installation location of the panel/battery bank.

The ineficience in the inverter would be a furthere kink in the system. At best.. you see 90% efficient inverters.. that's just another 10% energy loss to factor in to an already borderline powerthirsty system that is off the grid. Heavy copepr will offset the power drop.. higher dc transmission voltage will too.. all with a co$t though..

soundguy

As soundguy says the inverter would not be 100% efficient, and typically I would have to parallel two inverters ($$$) to get 240VAC. Plus the typical AC well pump is not very efficient, either. Fortunately my new high-efficiency whiz-bang pump will run on 48VDC or 240VAC or anything else remotely close, and I am counting on AC grid power for backup. Because while having running water when everyone else in the neighborhood doesn't would be very cool, being without it while everyone else has it would be downright embarrassing.

Garden system:

I am curious about operation. Will it run all the time sun is available?
What happens when the storage tanks you talked about are full? Is there some type of pressure switch/controller involved?

I expect it will run any time there is full sun. I haven't decided about a switch. One of the features of the current booster is a pair of switch leads I can use to shut off the pump with a float switch or other device (soil conductivity sensor?). All I would save by shutting it off is some pond water and the extra wear on the pump.

 

[chatcher]

That is why I said more cost effective, not more efficient. With the cost of copper these days to feed a current hungry device such as a pump, and with the losses in moveing DC any distance, a 10-15% inverter loss might be on par with the efficiency of his planned DC setup at far less cost in materials. It also opens the door to far less expensive AC pumps that still meet his need to revert to commercial AC or generator.

If you are only paying 1/4-1/10 the cost for the pump, that is more capital available for more solar panels, or higher capacity batteries, or just plain lowers the bottom line cost...

In my case the distances are not great and the pump is not very current hungry. In fact my current jet pump draws more current at 240VAC than the new helical pump does at 48VDC. For a daylight-only or grid-tied system (without battteries) I can see the cost of the pump vs. the cost of additional panels might push me toward using an AC centrifugal pump and inverters, but the cost of the battery bank needed to run it during dark hours would be the deal breaker. In my house system, I think the batteries are the weakest link.