newbie, with questions

rkymtnoffgrd · March 2011

Im interested in installing a solar direct pumping system 160' down in a 200' well with static water at 50'. I believe I'm sold on the grundfos setups likely a SQF or similar. Looking to get aprox 1500 gal/day. with aprox 400watts of pv. in southern california inland... Heres what I need help on, wire size? It makes sence to me to try to source the pv in such a way that the voltage to the pump is maximized and the wire size minimized. I think the pump will handle a wide range of voltage, but if I install the groundfos control module and the "generator backup" switch, doesn't the wire have to be configured for 120v....if the intent is to run the pump off the generator? If I say "forget it" to the backup generator then can I go with the maximum amount of voltage the pump can handle and is cost effective and feasible with the panels? Am I making sence? Suggestions please. I dont want inveters, transformers, or charge controlers etc...I'm looking for long term reliabilty first, cost effeciency second. Thanks! Also, how do you safely configure the wire when the static water level is 30-50 feet and im told the well can do 17 gals/min!! For that matter, how do you choose the pump with the same varibles...Thanks

mike95490 · March 2011

Re: newbie, with questions

You understand the pump is a DC pump and the "control box" is an expensive MPPT controller and current booster. Have you priced them yet, and the PV panels?

go to the http://www.grundfos.us/ site, and look at the pump curves for lift and volume for the family you want, and then you chose a model. Then price that model out. You need to select the pump for your use, not the pump that some dealer has had laying around collecting dust, and wants to get rid of it.

Assume your PV panels will put out 30-20% less than their nameplate spec, because they are not going to be aimed correctly all day long

You order submersible wire and water proof splice kits, and use a 120VAC heat gun (not a propane torch) to shrink the sealing heat shrink over the wire splices.

niel · March 2011

Re: newbie, with questions

also note that minimizing on the wire will maximize the voltage drop. that means subtracting voltage. thicker wire lowers the voltage drop and thus you keep more of the original voltage.

rkymtnoffgrd · March 2011

Re: newbie, with questions

Yes I have priced the system, assuming ive made no mistakes;
1) 101 Switchbox (used to shut of PV power and transfer to Gen)=$327
2) CU Control Unit ( Combined Status and Control Unit for Pump and allows for installation of float)=$245.00 The litature does not indicate that this is a "charge controller", I simply want it for allowing the float swith on the cistren, in fact I would not mind eliminating it if there is simpler (and stouter) float type on-off switch to the pump.
3) Water Level Switch =31.00
4) Pump 11 SQF -2 or 6 SQF-2 aprox = 2000k ( I don't know which one, if configured for lift at pump location its different than lift at water level, was looking for help on this. With a well that supposedly produces 17 gals a min...would I bias the pump for more volume or bias it for the lift even though it unlikly the water will drop much with the well production so high....
5) Panels...I havent even priced this yet, becasuse I need to know what to look for, If I have to configure for 120v due to pump,switch,control and generator backup, thats one thing...but if the panels exist and its financially feasible, perhaps a greater voltage is possible. what about 220v? If the pump can handle it, cant the generator backup be 220v? Wouldnt this be a better way to go?
6) Wire size...again varies drastically on voltage, I know the distance, but I could save a significat amount of money here if 1) I can series the PV panels to get to much higher voltages, if the switch and control box will allow it, and the pump can take it. Thanks guys... I appreciate the input.

rkymtnoffgrd · March 2011

Am I not mistaken that the flex series will accept 30-300v dc or up to 240v AC and that MPPT is internal in the pump? Of course, my next question is how difficult is it to source 400-600w of PV in such a way to series up to 220v (more panels, smaller size)? And if running 220v of PV will there be voltages spikes greater than 300?? Additionaly, is the line voltage drop different for ac and dc, the gen backup will be AC the PV is DC, the pump can handle either, how do I figure the wire? How high could I safely go? I don't know, its all rather confusing.

mike95490 · March 2011

Re: newbie, with questions

It's good to keep the wire size large enough to keep all losses below 2%

Most PV panels are rated for 600V and some newer ones, listed for 1,000V. It's typical to string them in series to get 300V or so.

You may need to buy an MC connector extenstion cable, and chop it in half, to get a couple of wires to plug into your PV's - &+. You DON'T want to cut the MC connector off the PV, that will void your 20 year warranty.

I thought the DC pumps had intergal water level sensors ?

BB. · March 2011

Re: newbie, with questions

When selection grundfos pump equipment, watch the various ratings and remember Voc-cold for solar arrays can increase by several 10's of percent if you have hard freezes.

I remember one max voltage as 190 vac when running from ac power.

-Bill

tmarch · April 2011

Re: newbie, with questions

rkymtnoffgrd wrote: »

Im interested in installing a solar direct pumping system 160' down in a 200' well with static water at 50'. I believe I'm sold on the grundfos setups likely a SQF or similar. Looking to get aprox 1500 gal/day. with aprox 400watts of pv. in southern california inland... Heres what I need help on, wire size? It makes sence to me to try to source the pv in such a way that the voltage to the pump is maximized and the wire size minimized. I think the pump will handle a wide range of voltage, but if I install the groundfos control module and the "generator backup" switch, doesn't the wire have to be configured for 120v....if the intent is to run the pump off the generator? If I say "forget it" to the backup generator then can I go with the maximum amount of voltage the pump can handle and is cost effective and feasible with the panels? Am I making sence? Suggestions please. I dont want inveters, transformers, or charge controlers etc...I'm looking for long term reliabilty first, cost effeciency second. Thanks! Also, how do you safely configure the wire when the static water level is 30-50 feet and im told the well can do 17 gals/min!! For that matter, how do you choose the pump with the same varibles...Thanks

What is the recovery rate of the well? This will tell you how deep you need to set the pump. Less depth=less wire. Most submersible wire is 8-10 gauge, if in doubt use the 10, not a lot of difference in price.
The Grundfos SQF should come with a low water probe so the pump will shut off before it burns up.
I have 2 SQF pumps hooked up directly to their 101 generator interface without the additional controller, they have worked for 3 years without a problem. Mine are pumping 5GPM+ @ 225 feet. I have hooked a generator up and it works so I'm happy.

solarvic · April 2011

Re: newbie, with questions

If you only need 1500 gal a day, I think I would get the plain SQ pump. I have one I am going to switch out a 220 v ac for. It is model10 sq/sqe-160 w 1/2 horsepower 110 ac. Has 1 1/4 inch discharge. . They are certified to run on mod/sine inverter and only has 10% surge which is 1100 watt. Rated to pump 10 gpm. with head of 164 ft. A decent 1000 watt msn 12 v. inverter should run it. If you arent going to use a pressure tank I think this would work just fine. Someone that knows more about how much battery storage and what to charge that one can figure it for you. I think that would be cheaper and just as reliable as using a dc pump. Since you are in southern CA. I wouldn,t think you would have any trouble charging the small battery pack you would need. Probably only need a small charge controler too. I found an ibternet site that sells them but don,t know how to attach the address. Don,t know if our sponser sells them but I saw them on voo doo solar. :Dsolarvic http://www.wwpp.com/ http://www.wwpp.com/products/grundfos-pumps/sq-3-inch-submersible-pumps.htm Here is some ibfo how to figure your head and friction loss

newbie, with questions

Comments

Categories