Help required to design off grid system

Cariboocoot

Re: Help required to design off grid system

It is perfectly normal for PV Voltage to go up and down on an MPPT charger as it will try to pick the optimum power point for the particular conditions during charging. With this type of controller, the output numbers matter more than the input. Along those lines, your high temperatures will work against you as they will reduce the Voltage available from the panels. This will make the charge controller adjust more to compensate.

Measure the Voltage and current going to the batteries from the charge source, as that is the only point at which it matters. You should see high current at lower Voltage to begin with, then as the batteries charge the Voltage will go up and the current will go down.

Do not trust the inverter as a measure of state of charge. Such things are nearly always only Voltage indicators, which is not the same thing.

Another problem with getting sufficient specific gravity is the amount of time the batteries spend at the Absorb Voltage point. If they are not held at that Voltage long enough, they will not fully recharge and the SG reading will remain lower than normal.

If the charge controller is one of those Wellsee units linked to, you are probably very limited in choice of settings. I doubt it has temperature compensation either, which would be quite important in a hot climate (higher temperatures necessitate lower charging Voltages). Along those same lines, the battery's SG may well be set lower than the 1.275 standard due to being intended to operate in higher temperatures (sometimes referred to as "tropical" SG standard).

niel

Re: Help required to design off grid system

maybe an eq charge will help. try 2 hours with about 58.5v and be very sure of the water levels too. use only distilled water.

Photowhit

Re: Help required to design off grid system

niel wrote: »

maybe an eq charge will help. try 2 hours with about 58.5v and be very sure of the water levels too. use only distilled water.

That's awful low for an equalizing charge, if his system has a battery temperature sensor I'd try for 61V.

Also the inverter/charger showing 100% state of charge(SOC) might well just be based on voltage and NOT a true state of charge. Even if the inverter/charger has a shunt it is likely the SOC would be based on the amp hours input verse output once hooked up to near dead batteries.

The SOC indicaters on a voltage based state of charge is only valuable after they batteries have not been charging for a few hours.

westbranch

Re: Help required to design off grid system

Guys , I searched for East Company and voila>>> Guangdong EAST Power Co., Ltd.
http://eastups.gmc.globalmarket.com/products/details/lcd-display-solar-charge-controller-60amp-lcd-display-398849.html


Syedbukhari Is this the MPPT CC You are using?


Link to picture

http://newimg.globalmarket.com/PicLib/606/705606/prod/0_1332471050699_m.png

I KNOW IT SAYS 48 v IN THE TITLE ON THE FIRST LINK BUT NO MENTION OF 48v IN THE TABLE???

BB.

Re: Help required to design off grid system

Also, if your bank is "sulfated" (sulpher is permanently locked in with lead into a crystalline form), you will also see low Specific Gravity.

And for a "sanity" check--Check a couple car batteries too and see what they read. It is not unusual for a hydrometer to not be calibrated, or some other issue (such as dirty/sticking float) affect your readings.

What was the solar array size (wattage), and what was the battery bank rating (volts/Amp*Hours, and per string--if you are disconnecting a string or more)?

Basically, batteries are pretty good during much of the charging cycle. If you take 100 amp*hours out, you need to return around 100-120 AH back.

And, once the battery reaches Absorb set point (say ~58 volts or so), you should hold it for ~2-4 hours or so to ensure that the battery is fully charged (the last 10-15% of battery charging takes time, the battery charging current slowly falls during this last part of the cycle).

Just reaching ~58 volts is not enough. "Shallow" cycling, perhaps 2 hours of "absorb"... Deep cycling, or trying to recover a "troubled" battery bank may need 4-6 hours of absorb voltage... As always watch battery bank temperature... You do not want to exceed the mfg. operating temperature (around 45-55C maximum temperature or you will risk battery damage).

-Bill

niel

Re: Help required to design off grid system

"That's awful low for an equalizing charge, if his system has a battery temperature sensor I'd try for 61V."

i know it's a tad lower, but not knowing the specs for his batteries i figured i'd err on the safe side of things just until we see results.

syedbukhari

Re: Help required to design off grid system

Cariboocoot wrote: »

Along those same lines, the battery's SG may well be set lower than the 1.275 standard due to being intended to operate in higher temperatures (sometimes referred to as "tropical" SG standard).

What sould be the minimum SG of my lead acid flooded batteires according to our hot climate?

syedbukhari

Re: Help required to design off grid system

westbranch wrote: »

Guys , I searched for East Company and voila>>> Guangdong EAST Power Co., Ltd.
http://eastups.gmc.globalmarket.com/products/details/lcd-display-solar-charge-controller-60amp-lcd-display-398849.html


Syedbukhari Is this the MPPT CC You are using?


Link to picture

http://newimg.globalmarket.com/PicLib/606/705606/prod/0_1332471050699_m.png

I KNOW IT SAYS 48 v IN THE TITLE ON THE FIRST LINK BUT NO MENTION OF 48v IN THE TABLE???

No i am using GF 2000

http://www.eastups.com/en/productshow.aspx?CateId=507&Id=198&PCateId=449
Please check this

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

.

And for a "sanity" check--Check a couple car batteries too and see what they read. It is not unusual for a hydrometer to not be calibrated, or some other issue (such as dirty/sticking float) affect your readings.

I have checked the reading with different hydrometers but the result remain almost same.

BB. wrote: »

.

What was the solar array size (wattage), and what was the battery bank rating (volts/Amp*Hours, and per string--if you are disconnecting a string or more)?

I am using four arrays of three panels and one panel having 220 watt.
12 batteries are using with the capacity of 200 Ahr of 12 volt.

BB.

Re: Help required to design off grid system

Your panels are:

syedbukhari wrote: »

Once again i need help from this forum
I have installed 14 panel on my fuel station with the following specification
Rating power at STC(Wp) 220W*
Open circuit voltage(Voc) 34.0V*
Short circuit current(Isc) 8.58A*
Rated voltage(Vm) 27.6V*
Rated current(Im) 7.97A

I used 2 strings of 7 panels by doing this i get 55.4 volts but failed to get desired amp and only getting 20-30 amps. In the beginning days i get up to 40-50 amp after few days it drops up to 25-35 amp. then i checked short circuit current of a panel it was 8.5 it means panel is generating its power rightly. Please guide then what is fault with this system?
I am using 48 volt battery bank
Please also guide can i charge 48 volt battery bank with 48 DC volt ?

Secondly the batteries are showing 1150 gravity and the multi meter showing 12.6 volt why this is so?

And you are using 12 x 12 volt @ 200 AH per battery?

Or is the battery bank 4x 12 volt in series, each battery around ~70 AH, for a battery bank of 48volts @ 200 AH total capacity (batteries in series add voltage, batteries in parallel add AH capacity).

How is your array currently configured? as 3 panels in series, with 4 strings in parallel--With one panel unused?

Also, do you have information on how may Amp*Hours (at what voltage) or how many Watt*Hours (or kWH) per day you are using?

Sorry--But I am still a bit confused. It is hard to do this all by typing (and you are doing it in a foreign, to you, language--I could not do it).

-Bill

Cariboocoot

Re: Help required to design off grid system

syedbukhari wrote: »

What sould be the minimum SG of my lead acid flooded batteires according to our hot climate?

This is a question that can't be answered except by the company that made the batteries. They will have set the SG at the factory to a particular point, and that's what you need to try for. Without knowing that factory number, we're all just guessing.

In this case what is most important is to get them all equal and as high as possible. By lengthening the Absorb time and/or applying an Equalization charge as Niel suggested you will be able to increase the SG reading - up to a point. When it stops improving there is no reason to continue trying to raise it; whatever you have at that time is all you will get from them.

Just to confirm:
You have three parallel strings of four 12 Volt batteries giving a total of 600 Amp hours @ 48 Volts.
You have four parallel strings of three 220 Watt panels for an array of 2640 Watts total.
You have an "all in one" inverter with charge controller built-in. Its maximum PV charge current is 40 Amps (SW-1 and SW-2 both set to '0') There appear to be no other user-adjustable charge parameters! This is terrible!

I would expect to see no more than 42 Amps maximum charging on that set up, or about a 7% rate. It should work provided the loads that are used at the same time as the charging occurs do not make the net charging rate too low.

syedbukhari

Re: Help required to design off grid system

BB. wrote: »

Your panels are:



And you are using 12 x 12 volt @ 200 AH per battery?

I am using 12 batteries
each battery has 12 volt and its capacity is 200 Ahr
Total watts for 12 batteries are 28800

BB. wrote: »

How is your array currently configured? as 3 panels in series, with 4 strings in parallel--With one panel unused?

Yes 3 panels in series with 4 strings in parallel with 2 panels unused.

BB. wrote: »

Also, do you have information on how may Amp*Hours (at what voltage) or how many Watt*Hours (or kWH) per day you are using?

I am using aprox. 14000 w*hr energy

BB. wrote: »

Sorry--But I am still a bit confused. It is hard to do they all by typing (and you are doing it in a foreign, to you, language--I could not do it).

-Bill

Yes you are right distance and language is problem to elaborate my views.

BB.

Re: Help required to design off grid system

syedbukhari wrote: »

I am using 12 batteries
each battery has 12 volt and its capacity is 200 Ahr
Total watts for 12 batteries are 28800

• 4 batteries in series, gives you 4*12v=48 volt battery bank.
• 3 parallel strings give you 3*200AH=600 AH battery bank @ 48 volts
• 600 AH * 48 volts = 28,800 WH = 28.8 kWH battery bank.

Yes 3 panels in series with 4 strings in parallel with 2 panels unused.

• 12 panels * 220 Watts = 2,640 watt array

I am using aprox. 14000 w*hr energy

Per Day???

You are using about 50% of your battery bank's capacity every day:

• 14,000 WH used / 28,800 WH battery bank = 0.49 / 49% of capacity used

That is a pretty heavy load for a battery bank... It will probably not last quite as long and you will have to be very careful to get it fully recharged at least a couple times a week.

More or less, your charging will be:

• 14,000 WH * 1/0.80 battery eff * 1/0.77 panel+controller losses * 1/2,640 Watt solar array = 8.6 hours of "noontime equivalent" sun per day

There are very few areas in the world were you will get that much sun, constantly, every day.

In north America, we use ~4.0 hours of sun per day as a, sort of, minimum assumed value to size a power system... If you are in a very sunny region, you may get 5 hours pretty consistently for 9 months a year.

My 0.80 (80%) flooded cell battery efficiency may be on the "conservative" side--And if you do things right, you may get closer to 90% efficiency (at least while the batteries are in very good shape--older batteries can become more inefficient) or:

• 14,000 WH * 1/0.90 battery eff * 1/0.77 panel+controller losses * 1/2,640 Watt solar array = 7.7 hours of "noontime equivalent" sun per day

At this point, your desired loads (I am assuming you are telling me 14 kWH of 48 volt DC loads, if it was 14kWH per day of 230 VAC AC loads, you would have another 1/0.85 for inverter losses too) and size of solar array are probably not sustainable. You need either to cut back on loads and/or add to your solar array.

In some ways, if you are using your AC power during sunlight hours (i.e., service station)--You are saving some battery losses (i.e., you don't have the 80% battery efficiency issues when the sun is up and, more or less, powering your loads from the solar array).

However, this can be an issue as this also reduces charging current to the battery bank which can be a problem too (we recommend ~5% to 13% rate of charge to a battery bank) and if you are drawing Y,YYY Watts during the day, you don't want the Z,ZZZ watts available for battery charging to be less than 5% rate of charge.

For example, a 5% minimum rate for a 600 AH @ 48 volt battery bank would be:

• 600 AH * 58 volts charging * 0.05 rate of charge = 1,740 watts to battery bank

Which leaves:

• (2,640 watt array * 0.77 controller+panel derating) - 1,740 Watt 5% batt charging = 293 watts average daytime DC load supported by array

And, I think, your DC loads during the daytime are probably much larger.

Many of our rules of thumb assume charging during daylight and discharging at night (at work during day, home at night cooking, TV, homework, lighting, etc.).

When you start mixing significant daytime loads into the design requirements, we need to make sure that all this continues to work together well.

Assuming that much of your power is daytime use, your battery bank may be OK with its current size--And you "just" (I know, adds a lot of cost for you) enlarge your solar array--Probably roughly double in size (just a guess at this time).

Yes you are right distance and language is problem to elaborate my views.

And yet, your posts have fewer errors in English grammar than mine (my only language).

-Bill

Cariboocoot

Re: Help required to design off grid system

Also, that 2640 Watt array will not supply the full 14 kW hours of power. More like less than half that:
2640 * 5 hours good sun * 0.52 over-all efficiency = 6864 Watt hours.

What might be typical for that amount of power in a totally off-grid scenario:

1,324 Amp hours @ 48 Volts (25% DOD) and two 4kW arrays with separate 80 Amp controllers.

But since you do have grid available you are probably not trying to supply all the power from solar, rather use it to supplement an unreliable utility.

westbranch

Re: Help required to design off grid system

I looked at the Inverter/charger specs and note that it has a max charge rate of 15 amps. http://www.eastups.com/en/productshow.aspx?CateId=507&Id=198&PCateId=449

I hope you are not relying on this charger portion to 'boost' your batteries...it is only marginal (~7.5%) at best considering the battery size (Ahr), the amount you are removing and what you are getting from the solar panels.

syedbukhari

Re: Help required to design off grid system

Yes i am not totally relying on solar because i have the option of main grid but still my inverter is producing 10 kw hr/day energy. It starts working from 8 am and continue to work till 5 pm. It charges the batteries with 38 amp @ 72 volts from 10 am to 2 pm. I am now quite happy with this system.
Thanks for every one who participated in this discussion.
Now i shall starts working on my tube well. I will share my results on this forum.

westbranch

Re: Help required to design off grid system

A good Battery Monitor http://www.solar-electric.com/metersmonitors.html
would be a very useful addition to this system so that you can ''see'' just what your batteries are getting for charge.

syedbukhari

Re: Help required to design off grid system

Hello every one
Once again i need your help to drive 5 HP motor for irrigation purpose.Please guide
What type of motor i should use AC or DC
What should be the minimum PV array required to drive 5 HP motor?
I wants to develop battery less system

Cariboocoot

Re: Help required to design off grid system

syedbukhari wrote: »

Hello every one
Once again i need your help to drive 5 HP motor for irrigation purpose.Please guide
What type of motor i should use AC or DC
What should be the minimum PV array required to drive 5 HP motor?
I wants to develop battery less system

Diesel.
No I'm not being facetious. 5 HP is a lot of power for generating with PV. It would require a huge array around 5kW and without batteries that power would not be sustainable, to say nothing of the start-up surge the motor would require. I know of no 5 HP DC motors, so you'd probably end up powering a 240 VAC motor.

The only other possibility I see is completely re-designing the irrigation system to use a lots of smaller pumps, like direct-drive Grundfos well pumps. But they would depend on the layout of the irrigation plan (water source, depth, delivery routes, destination, volume, flow rate, et cetera). Perhaps using something like the Grundfos to fill an elevated reservoir when solar power is available and then allowing gravity to do the distribution from there.

syedbukhari

Re: Help required to design off grid system

Cariboocoot wrote: »

Diesel.
No I'm not being facetious. 5 HP is a lot of power for generating with PV. It would require a huge array around 5kW and without batteries that power would not be sustainable, to say nothing of the start-up surge the motor would require.

Yes you are right production of 5 kw power is very costly but the fuel price is also very high in Pakistan. So i have to convert the motor on solar
Please guide can i use solar VFD (Variable frequency drive)to run the motor? and of which company VFD i should use?
5 Kw power is enough to run 5 HP motor?

Cariboocoot

Re: Help required to design off grid system

Sorry I can't advise you on VFD's. I know they exist but I don't work with them and therefor have no experience with various brands/types. Nor do I know what ones you may have available to you. Hopefully some of the other forum members who do handle VFD's will latch on to this and offer assistance.

Basic problem with running a constant RPM motor from solar is that solar isn't constant. That is why the batteries are needed: to store up the power available from the panels when it is available so that it can be utilized when needed. Therefore you have to consider the time factor as well: how much time you get sun for, and how much time you need to run the motor. This is why electricity is quantified as Watt hours, not just Watts.

Here's an example:
A 5kW array over 5 hours of "equivalent good sun" will produce about 19,250 Watt hours DC. But when you store that in batteries and then use it as AC you loose a lot of power. With those losses you may find you have around 13 kW hours to work with.

Technically a 5 HP motor draws 3,730 Watts. In reality this amount varies quite a bit according to how much load is on it. Best case that stored 13 kW hours would run it for about 3 hours. If you needed less run time you could use a smaller battery bank and array. More run time requires more battery for storing more power and a bigger array to recharge it.

The VFD will not save you much power per se; its purpose is to make starting the motor easier. Normally a motor like that will have a very large start-up current demand (especially against the weight of water) which places a great demand on both inverter and batteries.

DO you have any time factor for how long the pump would need to run?

BB.

Re: Help required to design off grid system

Here are a few threads with disucssions and links back to some vendors:

WELL PUMP and Inverter QUESTION
Wind/solar for large scale pumping etc (out of my depth!)
could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC

I believe that all of these are AC input VFD's... While it is possible to make a solar panel to VFD to large 3 phase (or other) motor--I have not seen any equipment recently that supports this configuration (I did find a company once, but could never find it again).

Here is an article about a 12 HP well pump powered by a custom Schneider Electric VFD in India... But there is not enough information to really understand if this is a Solar+VF+Pump or possibly just another Grid Tied system with Panel+GT Inverter+AC Mains+VFD+Pump (see what appears to be a power pole off to the right of the system).

Here is one Chinese (Mainland) company that appears to design a 2.2 kW version of what you are looking for:

[TH]Model/Item No.[/TH]
SGY2200L



[TH]Brand[/TH]
SETEC


[TH] Min. Order [/TH]
1


[TH]Country of Origin
[/TH]
Shenzhen , Guangdong , China (mainland)

Here is another search that has a 15kW result:

Zhuhai Saibite Electrical Equipment Co., Ltd. (China)
15KW Solar Power Off Grid (no battery) AC 3-Phase Water Pump Inverter/Controller
Min. Order: 1 Set FOB Price: US $1-100000 / Set

15KW Solar Power Off Grid (no battery) AC 3-Phase Water Pump Inverter/Controller
1 Big power and stable
2 ISO9001:2008

Anyway, that last search has a lot of results for solar powered VFD pumping systems from China... I hope this helps (I don't know anything about the links, companies, or their products).

-Bill

Cariboocoot

Re: Help required to design off grid system

For anyone reading this thread it needs to be pointed out that a 5 HP AC motor is not necessarily 3-phase. I've worked with many (and larger) such motors that were standard 240 VAC single phase.

syedbukhari

Re: Help required to design off grid system

I am also motivated after reading this Indian article. Now i am purchasing second hand VFD from the market just for experient because these are available at very cheap prices.
Thanks Bill for informing about the pumping inverters manufacturing companies. I contacted with one company. They send me the prices their prices are reasonable but there is no surety of their quality. So i first decided to try VFD if i failed to get the desired results then i will purchase pumping inverter.
Can anybody advise
Which type of VFD i should try?
Can every VFD take Dc input?
thanks

BB.

Re: Help required to design off grid system

There are just too many options/models/manufacturers to generalize that "all VFDs" can take DC input or not...

For your needs (AC pump + VFD + Solar array--lowest costs, least amount of maintenance)--You will really need to work with a local supplier or a manufacturer that is willing to work with you in country.

There is a very good chance that with your experimenting and experience you will be gaining--That you can make this a business and help others with their pumping/solar needs (more than a few people here have created solar based businesses after going down that road on their own first).

What I would suggest--Try to find a used 3 phase motor that would meet your needs (fit pump, correct size, etc.) and then send the motor/pumping specifications to a couple manufacturers and/or local representatives and see what they can do.

Also, if you know somebody with the local paper and/or somebody that writes on the Internet--You could "suggest" that they may get some free advertising out of assisting you. If you have a local university (or even trade school)--You could try enlisting their help/prestige too .

AC power, and especially 3 phase/poly phase power is a very complex subject (lots of math--I mean a very lot of math). There is probably little you can do to "help" or "play around" with a generic VFD to convert it to your needs unless you have a lot of engineering/electronics experience. Add trying to direct couple to a Solar array (which is a "current source" rather than a voltage source--that most equipment is designed to connect with)--And you should do much better with equipment designed for your needs--rather than trying to convert.

If, instead, you go with solar+battery+AC inverter (more expensive, less efficient, more maintenance), then as long as your solar PV AC system is large enough--Then you can probably run a "generic" VFD (single phase AC in, poly phase AC out to motor).

-Bill

syedbukhari

Re: Help required to design off grid system

I beleive VFD or inverter without batteries is the right solution for irrigation purposes all other methods are very expensive.
I am intereted to buy
Hyundai N 300
Lenze 8600
Yaskawa 616 G3
but confused which one i should buy?
Can you help me in this selection?

BB.

Re: Help required to design off grid system

You probably will have to contact the mfg/representatives... But, some links:

Hyundai N 300 200 or 400 VAC 3 phase input--No direct from solar array that I can see
Lenze 8600 appears to support DC input (could it be programed for solar power input?):

3 x 480 V AC, 45 to 65 Hz
Permissible voltage range: 330 ... 528 V
(alternatively 470 to 740 V DC supply

Yaskawa 616 G3 Do not see any DC input option

I don't think any of these will really do what you want them to do... The Lenze unit may be programmable to measure the DC input voltage/current, then a program could perform some sort of MPPT (maximum power point tracking) and control the pump based on how much solar power there is at the panels. But I would not think this would be easy.

If you have contacts with anyone that sells these VFD's, I would suggest you look at the links I gave you for solar pumping (perhaps even the article) that they can send back to the factories. I think that would help them understand your needs better.

Solar arrays are not "solar batteries"--They are sort of like the most ugly power you can imagine (current sources that vary with the amount of sun and temperature of the array).

It would be better to find/use an VFD designed and tested to run from a solar array (directly) rather than trying to program a standard VFD or "play" with one to see if you can get it to work (unless you have the experience and workshop to do such experimentation/reconfiguration).

-Bill

syedbukhari

Re: Help required to design off grid system

Eventually with help of your kind support i succeed to run my tube well motor with VFD.
I use Hyundai N 300 model.
In this model i have to set the frequency through manual nob. I am trying to develop a PLC from the market that can control its frequency automatically.This is only the draw back of this system. But hope fully we will over come on this problem.

stephendv

Re: Help required to design off grid system

Glad to hear its working, I'd be interested to know how you did it... What panel array voltage did you use? What happens when there's not enough current from the panels- does the pump stop completely?

syedbukhari

Re: Help required to design off grid system

stephendv wrote: »

Glad to hear its working, I'd be interested to know how you did it... What panel array voltage did you use? What happens when there's not enough current from the panels- does the pump stop completely?

I use 20 panels and give input of aproximately 540-600 Dc volt to the VFD.
The motor spec are
3 phase motor
Operatimg voltage 380-420
Operating current 8-10
RPM 1440
After providing the the input power i adjuct the fequncy through nob. First i run the motor at 40 HZ then i incresed the frequency upto 48 HZ. It works very well between these frequency ranges. Now i am enjoying to run my tube well at minimum cost. It still working very well. I will to upload its videos in few days. You will also enjoy to see this.

Kindly advice can i use different power and different specification panels in a system or the specification and the power should be same every time to extend the system power.