Grundfos sp 17-6 on PV

Khalid

Hello...

I was wondering if anyone has ever tried to run a big sp 17-6 pump or similar on solar energy?

It is a 3,8 kw 9,8A 380Volt 3 phase pump...

I know is it going to be expencive

Any input will be appreciated..
Best Regards...
Khalid..

BB.

Re: Grundfos sp 17-6 on PV

First question, Grid Tied or Off-Grid?

-Bill

Khalid

Re: Grundfos sp 17-6 on PV

Sorry.... Off-Grid... Diesel generator for backup...

BB. wrote: »

First question, Grid Tied or Off-Grid?

-Bill

mike95490

Re: Grundfos sp 17-6 on PV

how much does it need to run, just a couple hours a day, all daylight hours, or 24/7 ??

Heck it's a sizeable pump, you will need a 4.5 - 5KW size aray to run it @ prime solar hours, larger if you want to store to batteries.
It's likely to require even more to start, as the 3.8KW is the running power, needs maybe 2x that to start, a very large inverter. Maybe consider a DC motor, spinning a 3 phase gen head.

Maybe a new DC motor on it - save the conversion to AC.

Khalid

Re: Grundfos sp 17-6 on PV

mike90045 wrote: »

how much does it need to run, just a couple hours a day, all daylight hours, or 24/7 ??

Heck it's a sizeable pump, you will need a 4.5 - 5KW size aray to run it @ prime solar hours, larger if you want to store to batteries.
It's likely to require even more to start, as the 3.8KW is the running power, needs maybe 2x that to start, a very large inverter. Maybe consider a DC motor, spinning a 3 phase gen head.

Maybe a new DC motor on it - save the conversion to AC.

It needs to run about 8 hours in the summer and about 6h in the winter... its located in north africa and running daylight....

7,8kw array and 24, 12v/200A batteries...

3 x Out-back - VFX 3024E inverters...

Do you know of any reliable DC pump that can give 12-13000 liters/h at 55 meters?

mike95490

Re: Grundfos sp 17-6 on PV

mike90045 wrote: »

Maybe a new DC motor on it - save the conversion to AC.

What's the HP rating on the 3 phase motor you have, or the pump body ?

Make your own pump system.

Take the 3 phase motor off, and replace it with a DC motor, and spin your pump with that.

I'll try to guess, 4kW = 5.3HP
http://www.locost7.info/converter.php

What RPM's does your pump currently turn ? That's what the DC motor needs to turn at.
http://www.power-quip.com/motors1.asp?ci=6
Has some 5 HP DC, you will need drive electronics, but you are already looking at a trio of inverters anyway.

Solar Guppy

Re: Grundfos sp 17-6 on PV

I've never seen brushless DC motors in that HP range and forget brush DC motors, won't last more than a few months before skilled work is needed

Also, I think everyone is off by three, as this is a three phase motor so its more like 12kW total ( 4kw each phase )

Bottomline, this is a waste of time, no way anyone in africa is going to build a 100kw/battery backup system to replace a large genny ... unless its from the bank account of some lost prince that if you "only" pay the filing fee's you can have all the loot:roll:

mike95490

Re: Grundfos sp 17-6 on PV

Take a page from the Electric Vehicle folks, get a honking big motor, spare brushes, and a 'Zilla controller that will work straight off 200VDC Spin the pump with that.
Have a spare motor to alternate with/swap when you need to rebuild the commutator.

And armed guards for the 15KW of PV panels & batteries and copper wire.

Solar Guppy

Re: Grundfos sp 17-6 on PV

Mike, The electric cars use 3 phase AC motors as its the most efficient method for varible speed brushless motors. I "got into" this stuff with my DC powered pool pump project and even considered making a PV varable speed controller but found its been done already by a EU firm.

I cooked the brushes on my DC pump after 4 months, and after looking into more details found just running the PV gridtie and using a stock pool pump to be a better solution .. at least for Florida Pool needs.

Khalid

Re: Grundfos sp 17-6 on PV

If i use 24 x 12V 200A Batteries shouldn't that be enough to feed the inverters and run the pump??

Should 7,8kw array be enough??

Will also be keeping the old diesel generator for backup.

The current pump is an old 7,5kw 380V 3 phase, running of a diesel generator, and costing a fortune to run/maintain....

I would like to stick with Grundfos pumps as they are known to be very efficient and reliable....

I am hesitant using DC motor cause they need lots of maintaining

I have acces to panels at a very good price, that is why i am concidering running pv....

So there is no need for bank accounts of princes or armed guards, no one has the courage to steel form the property

Solar Guppy

Re: Grundfos sp 17-6 on PV

If you can't afford the Genny, you have no other options. Genny by FAR is the lowest cost approach

To handle about a 10kW DC load for say 12 hours a day, you would need about 100 batteries, a 100Kw PV system ... about 800K minimum US dollars

BB.

Re: Grundfos sp 17-6 on PV

How are you using the water? Do you need high pressure for irrigation/spraying or can you convert to using ditches and syphons to move the water to the fields (save energy/fuel/panels required if you reduce pressure).

Would it be cost effective to use numerous smaller wells/pumps and use solar powered pumps (no batteries) to just pump during the day (to field/tanks/ponds).

If you need the large pump, and can live with just pumping during daylight hours--it may be worth contacting Grundfos to see if they have a pure solar panel option for you.

If you can get rid of the batteries, such a system may be competitive with your diesel generator...

But, in any case, looking towards conservation (reducing water use, reducing water pressure, installing new pump/motor, more wells to reduce lift requirements, separate irrigation pump--low pressure day use only--vs home low volume higher pressure 24x7 use, etc.) is the first place you will want to explore. If you could cut your energy use by half (just a guess), whether it means 1/2 the solar panels or 1/2 the fuel used in the generator, you will still be better off...

Also, what about a direct diesel motor to pump connection--and not going through the generator/motor electrical connection... You may save quite a bit on fuel right there (assuming that this is even mechanically possible). Energy conversions (mechanical->electrical->mechanical) generally have quite a few conversion losses. It won't eliminate the fuel costs, but might save money.

-Bill

mike95490

Re: Grundfos sp 17-6 on PV

Khalid wrote: »

The current pump is an old 7,5kw 380V 3 phase, running of a diesel generator, and costing a fortune to run/maintain....

WHAT is the Size of the Diesel Engine that turns the existing generator ? Convert that HP to KW, and that will be 70% of the PV array you need to only run in daylight.
example of math
80HP = 60KW needs 78KW of PV to run the pump.

Very expensive for the first 10 years.

Khalid

Re: Grundfos sp 17-6 on PV

I am using dicthes already, so no need for high pressure.. the option with direct diesel motor to pump connection is no good, to unreliable..

Numerous smaller wells/pumps, also no good.

I would very much like to get rid of the batteries is there any way this is possible?

I'm only pumping during daytime...

Thanks for all the replys...