Help required to design off grid system

BB.

Re: Help required to design off grid system

Thank you for the link "Syed",

I personally do not need a well pump (on city water), but I believe the battery less well pump setup with "cheap and reliable" three phase motors will change a lot of lives, around the world, for the better.

Your project is extremely encouraging.

Take care,
-Bill

Rossman

Re: Help required to design off grid system

It's exciting to see people in this forum helping others around the world!

syedbukhari

Re: Help required to design off grid system

Now I need help to run a DC motor on solar.

Please advice is it better to run a DC motor of higher voltages on solar?

I think if we run a Dc motor of higher voltages on solar we can save inverter cost and 20 % of energy losses that is caused during conversion from DC to AC.

What do you think?

If this idea is ok then what type of DC motor should I use?

BB.

Re: Help required to design off grid system

What size of motor/application?

-Bill

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

What size of motor/application?

-Bill

At least 5 hp motor should run for irrigation purpose.

Cariboocoot

Re: Help required to design off grid system

syedbukhari wrote: »

At least 5 hp motor should run for irrigation purpose.

That is quite a large size motor: almost 4kW. Trying to run that on low Voltage would require huge amounts of current and be terribly inefficient. Normally a motor tat size would be 240 VAC and draw 15-20 Amps. I don't see this happening on DC.

syedbukhari

Re: Help required to design off grid system

Cariboocoot wrote: »

That is quite a large size motor: almost 4kW. Trying to run that on low Voltage would require huge amounts of current and be terribly inefficient. Normally a motor tat size would be 240 VAC and draw 15-20 Amps. I don't see this happening on DC.

What do you think if we use higher voltage motor (200-600volt)?

I think it I not impossible and difficult to run a higher voltage motor. Can you suggest what type of Dc motor should I use?

Cariboocoot

Re: Help required to design off grid system

syedbukhari wrote: »

What do you think if we use higher voltage motor (200-600volt)?

I think it I not impossible and difficult to run a higher voltage motor. Can you suggest what type of Dc motor should I use?

Even if there were such DC motors available it would be difficult to control and very much more dangerous than AC. A battery bank capable of sustaining 15-20 Amps DC @ 240 Volts would be massive and have a current potential that could melt steel in an instant, to say nothing of copper or starting fires. It could also electrocute people very easily.

Unlike AC, DC does not pass through zero Volts regularly. It stays at the rated Voltage. This is why components such as switches and breakers rated for AC often do not work on DC; they can't safely interrupt the flow.

This is similar to (but not entirely the same as) a grid-tie system where the array runs around 400 Volts and 10-20 Amps. Those arrays are dangerous for the same reason of electrocution potential, but there is no massive stored Amp hour capacity.

I do not believe you will find a DC motor to produce the kind of HP you require. This leaves you with two options: use AC either through an inverter (same sort of problems with current but can be better contained) or generator or power the pump directly from an engine.

The other possibility is to change the HP demand of the irrigation system. Often these use large pumps to move a lot of water in a short period of time. If you can rearrange it to require the same volume but spread out over more time then you can use smaller pumps. Perhaps even storing water up in a tank above the fields when possible and allowing gravity to release it as needed.

My only experience with this sort of thing directly is examining the possibility of powering some irrigation pumps from PV for my son-in-law's father. It was so incredibly impractical upon the first calculations that we dropped the idea entirely. In that case it was three 15 HP 3-phase pumps and due to the nature of the pumping requirements the capital investment involved would pay the utility bill or even diesel fuel bill for more years than he or I have left to live.

BB.

Re: Help required to design off grid system

Syed,

Why not a VFD + 3 phase AC motor solution.

You are my hero here on VFD+Solar water pumping solution! I would like to read more about the details of your VFD irrigation solution someday.

At a very simple level--Simply plugging an appropriate sized (voltage/AH) battery bank into a DC input compatible VFD and you are done (from that point of view).

The next question is charging the (probably) high voltage DC battery bank. True high voltage/reliable/MPPT type solar charge controllers are not common items. There are ways of doing it (make your own PWM type controller, or place several MPPT controllers on bank segments--like 48 volt bank segments for a 480 VDC bank). But this is expensive, runs into possible wiring/control issues (different "grounds" for each MPPT controller) and the fact that high voltage DC Battery banks are pretty dangerous. Not something that the typical "farmer" would or should manage without a lot of safety training/face mask/fire proof clothing.

So why not VFD or your Solar=>VFD=>3 phase pump you are using today? Does he need to pump in poor weather/at night? Just a very basic assumption is that a battery based system is going to use 2x the solar array and 4x more costly than your "no battery" system you have today.

-Bill

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

Syed,


So why not VFD or your Solar=>VFD=>3 phase pump you are using today? Does he need to pump in poor weather/at night? Just a very basic assumption is that a battery based system is going to use 2x the solar array and 4x more costly than your "no battery" system you have today.

-Bill

Yes off course VFD + 3 phase pump without batteries is the best solution so far but I just wants to do an experiment to run DC motor without battery and inverter as well. I will try to do this experiment with Dc motor but before this I wants to gets maximum information and difficulties that may arise during this experiment as I did last time, I discussed about VFD on this forum and get many valuable information from here that help me in running of pump through VFD. What do you think now?

BB.

Re: Help required to design off grid system

Well--We get into the whole discussion of what a DC motor is... There is the traditional "Universal" or Brushed Motor.

http://en.wikipedia.org/wiki/Universal_motor

The motors are relatively efficient and easy to use. And if you remember the older cars that use a DC generator, you can even convert those into DC motors. The weakness of brushed motors are the brushes... A good motor will only run ~6-12 months running 8-24 hours per day before the brushes need replacing--And possibly the commutator needs to be turned on a lath to turn it flat again. Brush motors are also electrically noisy (interfere with radios/tvs) and can produce Ozone which is hazardous to people if contained in a building/shed.

Here is a great manual on Brushed Motors (I took a quick look and learned new things--Brushed motors do not like hot/humid environments):

http://www.baldor.com/support/Literature/Load.ashx/MN605?ManNumber=MN605

Baldor motors are some of the best motors produced/sold in the US. One of their general purpose 5 hp DC motors is ~$11,000 each (list price). Not cheap

Then we get to DC Servo motors--Which are usually permanent magnet motors but they still need a rotating field (i.e., VFD or similar servo drive). Very efficient, long life, and reliable.

Lastly, was the 3 phase induction motor--Still requires a VFD, but cheaper (and perhaps 10-20% less efficient) because of the rotor generates a magnetic field via "induction" (the "slip" between the rotating filed and rotor itself creates current and a magnetic field in the rotor) vs the use of permanent magnets (which can be very expensive).

-Bill

syedbukhari

Re: Help required to design off grid system

Hi friend how r u?

Once again i need your help to run a passenger lift on solar. The motor is consuming 4 amp on each phase and voltages are 420 Volts. How can i run this on solar?

BB.

Re: Help required to design off grid system

Syed, doing pretty well... I can't complain (and nobody would listen anyway).

Is this an elevator or escalator (moving stairs) application?

If elevator--Is only moving when the sun is out really acceptable (sun goes behind clouds, people trapped in lift)? Escalators are probably very energy inefficient.

In the US, elevators (and other passenger moving devices) are highly regulated by state/federal safety laws. I would not even want to guess how somebody could do a "solar only" passenger lift.

Otherwise, it is just another electric motor. Passenger lifts are not usually very small or energy efficient. Not something that I would see as being a natural for moving people (without Battery/Utility power).

-Bill

drraptor

Re: Help required to design off grid system

syedbukhari wrote: »

Hi friend how r u?

Once again i need your help to run a passenger lift on solar. The motor is consuming 4 amp on each phase and voltages are 420 Volts. How can i run this on solar?

we are all fine

In which city you are going to install this ? IMHO, that is a AC motor, so you will also need a Inverter.

Which brand of panels you are using ?

As for your Water pump invention Iqbal said:
Attachment not found.
Translation

Nahin Hai Na-Umeed Iqbal Apni Kisht-e-Weeran Se
Zara Nam Ho To Ye Mitti Bohat Zarkhaiz Hai Saqi

But of his barren acres Iqbal will not despair:
A little rain, and harvests shall wave at last, oh Saki!

http://iqbalurdu.blogspot.com/2011/04/bal-e-jibril-009-digargoon-hai-jahan.html

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

Syed, doing pretty well... I can't complain (and nobody would listen anyway).

Is this an elevator or escalator (moving stairs) application?

-Bill

Thanks Bill for your kind support every time.

The lift is an elevator and working hours are from 7 am to 5 pm. There is also an option to attach the batteries for the emergency use only.

But mainly the client is interested in operate it maximum on solar and he is interested in battery free system and he is preferring to use generator or utility grid in case of emergency or in cloudy days

What you suggest now?

syedbukhari

Re: Help required to design off grid system

drraptor wrote: »

we are all fine

In which city you are going to install this ? IMHO, that is a AC motor, so you will also need a Inverter.

Which brand of panels you are using ?

In Multan city, Yes you are right we have to use the inverter for this. We are using HT- SAAE solar panels in our commercial installations.

drraptor wrote: »

As for your Water pump invention Iqbal said:
Attachment not found.
Translation


http://iqbalurdu.blogspot.com/2011/04/bal-e-jibril-009-digargoon-hai-jahan.html

I am very thankful for your great appreciation but still i think we have to do more. Are you from Pakistan?

drraptor

Re: Help required to design off grid system

syedbukhari wrote: »

In Multan city, Yes you are right we have to use the inverter for this. We are using HT- SAAE solar panels in our commercial installations.



I am very thankful for your great appreciation but still i think we have to do more. Are you from Pakistan?

you are welcome.
what are rates for the HT- SAAE panels ? I haven't seen these panels in Lahore. My friend need a Solar tube well setup in Chiniot.

syedbukhari

Re: Help required to design off grid system

Here are the picture of two new recent solar pumping system project just to awareness about cheap pumping system.

drraptor

Re: Help required to design off grid system

syedbukhari wrote: »

Here are the picture of two new recent solar pumping system project just to awareness about cheap pumping system.

you can post the video on dailymotion, PTCL recently signed a agreement with it.

drraptor

Re: Help required to design off grid system

What are the system specs for these 2 ? you are also using Pole mounting, we had a very fierce debate on Wind conditions in Pakistan which you check at http://www.wiredpakistan.com/index.php?/topic/21710-solar-system-with-tracker/page-4 (if admins don't mind :-))

syedbukhari

Re: Help required to design off grid system

drraptor wrote: »

What are the system specs for these 2 ? you also using Pole mounting and we had a very fierce debate on Wind conditions in Pakistan which you check at http://www.wiredpakistan.com/index.php?/topic/21710-solar-system-with-tracker/page-4 (if admins don't mind :-))

Lower Punjab is very famous regarding to wind and storm but Alhumdulallah our client did not face any problem so far. It is not automatic tracking system but it is tracked manually 2-3 times in a day. It is very easy and simple to operate only one man can rotate with his finger tips only.

drraptor

Re: Help required to design off grid system

syedbukhari wrote: »

Lower Punjab is very famous regarding to wind and storm but Alhumdulallah our client did not face any problem so far. It is not automatic tracking system but it is tracked manually 2-3 times in a day. It is very easy and simple to operate only one man can rotate with his finger tips only.

can you share more pics of that mount. As for tracking, pre-assembled circuits/kits are available at Hall road for as low as Rs200 (~$2) , you just need to find the exact price of actuator required.

syedbukhari

Re: Help required to design off grid system

drraptor wrote: »

can you share more pics of that mount. As for tracking, pre-assembled circuits/kits are available at Hall road for as low as Rs200 (~$2) , you just need to find the exact price of actuator required.

At the moment i do not have picture of the structure but i can share these later

BB.

Re: Help required to design off grid system

syedbukhari wrote: »

The lift is an elevator and working hours are from 7 am to 5 pm. There is also an option to attach the batteries for the emergency use only.

But mainly the client is interested in operate it maximum on solar and he is interested in battery free system and he is preferring to use generator or utility grid in case of emergency or in cloudy days

What you suggest now?

I still think that large water pumping systems with nothing more than a solar array + VFD + 3 phase motor is as close to "magic" as you can get. It looks like it is working out very well for you. Manual tracking--Looks like you may also have an installation with pairs of array pointed at 90 degrees to each other ("virtual tracking").

How has it all been working out for you and your customers?

Regarding the elevator--In theory, a VFD and three phase motor (or Servo motor with permanent magnets for higher efficiency and better low RPM performance--I think) would be pretty much the same as your water pumping solution. Slower operation morning/evening. You could even setup a reference circuit that would switch the VFD to AC mains (or, in theory battery bank) to keep the elevator powered in poor weather/ends of the day.

Is this a conversion of an existing elevator or new installation. The "old fashion" elevator with manual gates would make the powering much easier (don't want people stuck in cab when solar power "fails".

In the US, many small installations are hydraulic. Big cylinder drilled into the ground, a hydraulic pump for pressure to lift, and the "cab". Very inefficient. 100% of energy to lift cab+people. But, you could setup to simply dump pressure to bring cab to ground (when power fails).

Cable lifts generally have a counterweight--So you have less loads (cab weight is balanced by weight). But can be more complex (automatic brakes to prevent broken cable from dropping cab, etc.).

In the US, even a smallish hydraulic elevator uses a very large electric motor (20-40 Horse power or ~15-30 kWatt).

I don't know enough about elevators to be of much use--And your local requirements/what is acceptable (automation, speed, etc.) are probably different than in the US anyway. And you can probably make a big difference between the elevator used all day long in a store/office--Or at a school for handicapped students a few times a day.

I would work with a local elevator supplier and see if they would even consider your proposal... Showing them your large solar pumping installations would probably show them you are "real" and not just wasting their time.

Just for the heck of it--googled "solar powered elevator" and actually got hits:

http://www.schindler.com/us/internet/en/about-us/solar-impulse-across-america/reimagining-mobility.html
http://www.schindler.com/us/internet/en/about-us/media-north-america/press-releases/Press-Releases-2013/schindler-introduces-worlds-most-advanced-elevator-that-can-be-p.html

The above links seem to be just DC servo type system (fearless, efficient, use battery bank for backup/energy storage like a hybrid car). Claims to use ~60% less power than traditional elevators--Probably a reasonable claim over a traditional system.

http://elevatortoday.com/2012/10/13/mezolift-first-solar-elevator/ (designed for 30 lifts per day from solar+battery bank)

So--If you keep the elevator lightweight/energy efficient and are not looking for high traffic use--It does seem possible. But--Using a battery bank or grid/generator backup is going to be a requirement--Unless you are prepared to design/build something local (with acceptable backup/emergency power/or "power off" operation--return to ground floor).

-Bill

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

I still think that large water pumping systems with nothing more than a solar array + VFD + 3 phase motor is as close to "magic" as you can get. It looks like it is working out very well for you. Manual tracking--Looks like you may also have an installation with pairs of array pointed at 90 degrees to each other ("virtual tracking").

How has it all been working out for you and your customers?

Its working is good and the customers are quite satisfied with the performance. I think auto tracking system is not feasible for our region because in summer season there is frequent wind and storm that can disturb the functioning of the system. To combat against wind we have to design a system that should be close to fix structure in order to increase the strength and reliability of the system.

BB. wrote: »

Regarding the elevator--In theory, a VFD and three phase motor (or Servo motor with permanent magnets for higher efficiency and better low RPM performance--I think) would be pretty much the same as your water pumping solution. Slower operation morning/evening. You could even setup a reference circuit that would switch the VFD to AC mains (or, in theory battery bank) to keep the elevator powered in poor weather/ends of the day.


-Bill

Yes i am 100 % agree with your system suggestion but i have only one problem how can i charge the batteries from solar. As VFD support the batteries, solar and AC supply that's why i wants to use 26 batteries of 50 AH with the VFD but i have main problem of its charging because charge controller of 312 Volt i think not available in the market. How can i overcome on this problem?

BB.

Re: Help required to design off grid system

Even way higher than 312 volts nominal battery voltage (upwards of ~420 vdc or more).

I agree, nothing I have seen can manage that high of bank voltage, and I would worry that the battery cases themselves would need extra electrical insulation (cannot put on concrete or near metal boxes/supports). And working on a 312 VDC battery bank--Would scare the daylights out of me (arc flash burns/hazards).

At this point, there is just not much in the way of high voltage DC solar charging out there. Midnite (last I saw) has discontinued their 250 VDC input charger (and higher battery voltage) charger (due to lack of sales?).

There is a ~380 VDC initiative that wants to use this working voltage for computer data centers (many computer power supplies can be direct connected to 380 VDC just fine).

https://www.google.com/search?q=380+vdc+data+center

There should be a solar charger solution--Solar power was one of the justifications of this high voltage/high power systems.

Otherwise, it is just the usually 12/24/48 vdc battery bank to 230 VAC inverter solution.

The design of the elevator is going to make a huge difference in power requirements--15 kW vs a couple kW operating power.

-Bill

syedbukhari

Hi all Respected members:

I am searching for used solar panels in bulk. Can any one help me in this matter?

BB.

I am guessing you want to buy enough to fill one or more shipping containers to Pakistan?

-Bill

jcheil

syedbukhari wrote: »

Hi all Respected members:

I am searching for used solar panels in bulk. Can any one help me in this matter?

Why used?
New panels are actually cheaper than used panels.
All the used panels "I" see for sale are old 12v panels and they are over $1.00/watt.
New panels are $0.70/watt or less.

syedbukhari

BB. wrote: »

I am guessing you want to buy enough to fill one or more shipping containers to Pakistan?

-Bill

Yes Bill you are right. I am looking for at least on 20 ft container but in a very reasonable price.