Grundfos 6-SQF-2 controller needed??

[Texas Wellman]

MPPT is built into the grundfos.

If that pump does incorporate an MPP function, the voltage from the solar array
will be fairly constant while it runs over the day, at the Vmp of the panels. This
doesn't change a lot over varying sun, if there is no partial shading. If the voltage
varies widely, an MPP controller would likely increase efficiency & power. Bruce Roe

[bcroe]

Mpp

The pump/motor doesn't care what the input power is as long as it's 30-300VDC or 90-230 VAC. You don't need the interface box and you can run it just like a regular well pump or even direct solar (I don't recommend wiring direct).

If that pump does incorporate an MPP function, the voltage from the solar array
will be fairly constant while it runs over the day, at the Vmp of the panels. This
doesn't change a lot over varying sun, if there is no partial shading. If the voltage
varies widely, an MPP controller would likely increase efficiency & power. Bruce Roe

[Texas Wellman]

The pump/motor doesn't care what the input power is as long as it's 30-300VDC or 90-230 VAC. You don't need the interface box and you can run it just like a regular well pump or even direct solar (I don't recommend wiring direct).

Hello,

I'm new to blogging, but have been developing my 5 acres of paradise in the mountains for several years.
When we bought the property it had a 240v well pump but the down pipe was shot. We replaced the pump with a 6 SQF-2 and down pipe w schedule 120pvc and stainless connectors. We have been running the well pump off of generators with no controller, but I now want to run it direct off of a 790w 50vdc array. I want to put a timer on it so it comes on a couple hours a day to top off the 2.6k gal tank uphill and the overflow waters the garden. Has anyone wired an SQF pump dc without the Grundfos controller? I've been doing with ac without any problems. The controller is 300 bucks and really doesn't do much for you except allow for a float switch, which I don't want anyway. BTW there is no power for 20 miles

Thanks,

[sfblackrobe]

I'm late in replying to this thread. But this may be helpful to some.

We've got two wells with Grundfos 6SQF-2 and -3. We built our own controller to use solar panel DC (direct, no batteries, no inverter) when the sun is out and producing enough power to drive the pumps. It switches to AC grid when there's no sun and we need water. We've also got a timer as part of the system. We're using the Irritrol pccontrol for irrigation and it has a "landscape lighting" feature, so to go to solar power we need two things: 1) it's got to be in the time range we've set; 2) there's got to be enough voltage on a single panel (now set for 38 VDC) to insure enough power on the panel arrays (3 and 4 panels respectively).

It's working fine. We can pump 5,000 gal/day when needed.

[Mike90250]

Add the socket, retention clip, and a "inductive kickback" diode, and you should be OK.

A relay coil without a anti-kickback diode, is also called an automotive ignition coil

http://en.wikipedia.org/wiki/Snubber#Diode_snubbers

http://www.allaboutcircuits.com/vol_3/chpt_3/9.html

[kmmtnman]

Relay

Make sure the relay can handle the DC amps and volts, without burning up or welding the contacts. AC devices used in DC circuits don't last long.

This is what I bought. Looks like it should be up to the task. Bought a spare too. Hope it works..

http://www.alliedelec.com/search/pro...x?SKU=70174878

[Mike90250]

Make sure the relay can handle the DC amps and volts, without burning up or welding the contacts. AC devices used in DC circuits don't last long.

[HBB]

Hello Kmmtnman,

Thanks for your reference to the Grundfos Pdf. I downloaded and read it carefully.

Perhaps the best way to proceed is to do the test setup they mention in page 52, with a swimming pool and do the test @ 48 VDC and @ 100 VDC
I have all the stuff but the manometer.

I will come back with the info if I get it.

Thanks very much for your cooperation,

Kind regards,
Horacio

[kmmtnman]

Hi Kmmtnman,

1. Grundfos info

Please point me to the Grundfos efficiency link where you got the quoted data.
It is interesting for me also to know about efficiency and increase mine !
If there is a significant efficiency increase going from 48 VDC to 96 VDC I will think about ...
Anyway, I kindly ask you to point me to the Grundfos quoted ut-supra.

Thanks for this info exchange !

2. Your setup

If the panels are not close to the pump your are absolutely right on doing a setup @ 100 VDC.

Looking to hear from you,
Have a nice week end
Horacio

Horacio,
It's at the bottom of page 17 in this pdf file. Says to configure your panels for 120v or more.
Hope the link works for you.

http://us.grundfos.com/products/find-product/sqflex/_jcr_content/tabbedpanel/brochures/par2/downloads/download_1/file/file.res/L-SQ-TL-031.pdf

Makes sense, More volts, less amps, less loss, and it wont have to grunt so hard to get started.
Let me know if you try it and it improves your systems performance.

[HBB]

Grundfos states that thou the pump will run at 30vdc it performs best at 120vdc.

Hi Kmmtnman,

1. Grundfos info

Please point me to the Grundfos efficiency link where you got the quoted data.
It is interesting for me also to know about efficiency and increase mine !
If there is a significant efficiency increase going from 48 VDC to 96 VDC I will think about ...
Anyway, I kindly ask you to point me to the Grundfos quoted ut-supra.

Thanks for this info exchange !

2. Your setup

If the panels are not close to the pump your are absolutely right on doing a setup @ 100 VDC.

Looking to hear from you,
Have a nice week end
Horacio

[kmmtnman]

50 vs 100 vdc

Horacio,
It sounds like your system works well without the 300dollar controller. I'm going to build my own as follows.
I have 2 200w sanyo 50v panels and 2 195w 50v panels. Currently running all in parallel for 50vdc at the charge controller. I plan to install a relay that will put the parallel pairs in series for 100vdc to the pump. I'll actuate the relay from a timer and the pump will run on a schedule (if sun is available) and not deplete my batteries. I don't want a float as the overflow from the tank will be used to irrigate my garden, pond etc ... Probably wont get to it until the snow melts thought i have already purchased 4pdt relay.

Thanks for your comments.

Grundfos states that thou the pump will run at 30vdc it performs best at 120vdc. Also my array and power shack are not close to the well so the higher voltage should allow for less v drop over roughly 500feet (1000 ft round trip) from the panels to the pump. I could run the charge controller at 100vdc as well but in certain conditions it may over volt the controller. The relay will normally run to the charge controller and when timer activated it will divert all the power to the well. Batteries stay charged and the tank will overflow to the pond and garden.. That's the plan anyway. Have to see how it works when the snow melts..

[HBB]

Hello Kmmtnman,

This is a quick answer, having more info from you I will complete it.

1. I understand that your limitation is in the controller, as far as you cannot drive the pump (Need minimum 30 VDC to start) from a 24 volt setup. Right ?
That is why I made a 48 Volt setup. My pump does not deplete my batteries when there is sun. My regulator is smart enough to drive the pump first and divert the surplus energy to the batteries.

2. Why do want to mess up to switch in series? Do you feel that the pump has better efficiency @ 100 VDC than @ 50 VDC ? I do not feel like that.
Dont forget Grundfos tech is very high, and for sure there is an MPTT logic inside that little pump. Not sure but it behaves like.

3. Have you measured the Q [GPM] or [Liter/Hour] under these conditions:

3a. 110 or 220 Volt genny ?
3b. with 50 VDC coming from your 4 parelleled panels ?
3c. with 100 VDC coming from your 4 series/parallel panels ?


4. Do you have the curve Q vs H of the pump for different P[Watts] ? If not I can provide it to you.
For instance:

My 1.2-2 takes:

at no charge (H=0) under 48 Volt gives 1200 (one thousand and two hundred) liter hour @ 2.35 Amp

[kmmtnman]

[QUOTE=HBB;40547]Hello kmmtnman,

I have a SQF 1.2-2 that gives me 1.000 Liter/hour @ 22 meter head.

I run it from a 48 VDC battery array, which is charged via solar + generator unit for long no sun periods.
The pump feeds a 100 hectare cattle breeding farm near the Uruguay river.

I have a DIY switching scheme that perfectly replaces the Grundfos box, of course is not a "professional" but is functionally correct.

You dont say what power you will be using. In my install I use about 180 watt, so the pump drains a bit less than 4 Amp

[russ]

Hello,

One thousand liter per hour. Sorry for using the dot as decimal separator.

Kind regards,
Horacio

Same is used here - confusing at first glance and then I became accustomed to the method.

[Naptown]

Hello,

One thousand liter per hour. Sorry for using the dot as decimal separator.

Kind regards,
Horacio

No problem This is a more realistic number.