Need wind and solar chargers

arisiakovo
arisiakovo Registered Users Posts: 1
in General Solar Power Topics #1
Hello,

I need chargers for wind generator and solar panels.

I have a ~12KW (51x235) stand alone pv system.
Max Power: 235W
Max Current: 7.68A
Max Voltage: 30.60V
Connected 4 pannels in series. 12 string of 4 pannels in parallel. See schem below.

Attachment not found.

In every string I have put in series diodes and 10A fuses.
The location is in central Greece.

I have 96 Volts 500Ah lead acid battery bank. (2Volt X 48pieces in series).

I have the following three phase off grid inveter.
Power: 15kW
output voltage: 3phase 400VAC 50Hz
DC voltage: 96VDC

I have the following MPPT charge controler.
Charge curent: 100A
Solar input: max 168V
Rated power: 10kW
Battery: 114V(overcharge), 109V(charge), 80V(discharge)

1)The system works fine and it handles 30kWh per day consuption. I think that it can handle more power. How many kWh per day should I store to the batteries? I think that for this system I should store 45 to 50kWh. If yes please advice for solar chargers that can charge the 96VDC battery bank. I want solar charger to has options to set the max charge point to 120VDC so that I can store the whole power to my battery bank.
2) What is the best conbination of solar chargers for the above system?
3)How can I connect my 3kW three phase wind turbie in this system?
4)Will I have any compatibility problem between solar and wind chargers? If yes please advice chargers that are compatible to each other.

I can't change my 96VDC battery bank array.

Sorry for the length of this post and for any mistakes this is my first post. I am waiting for your replies. Thank you in advance

Aristidis
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Need wind and solar chargers

    My first question is the strings of 4 panels and the last string with 3 panels tied into the second to the last 4 panel string. At best, it should not help much. At worse it may damage the top panel in the second to last string.

    Do you have a solar charge controller today? If so, the blocking diodes per string are not usually needed. If you current do not have a proper solar charge controller (which normally does the "blocking" of back feed from battery bank), then yes, you should have the blocking diodes to reduce leakage current at night.

    Regarding a "proper" MPPT charge controller for your battery voltage--The only one that I know of (I am not in the business, and don't know anything from Europe) is the Midnite 250ks 35 amp MPPT charge controller.

    You actually have several configurations for controlling your battery bank state of charge... You put a solar charge controller between the array and the battery bank (charge controller "turns on" to charge the battery bank and turns off to stop charging--a "series" type charge controller).

    For the wind turbine, you place a "dump controller" on the battery bank. When the battery bank is full (from your direct connected solar array + DC rectified wind turbine output) and the excess energy generally goes to some form of heater (air, water) or alternate load (water pump to tank, storage pond, etc.). For safety, in the US, our code would require two dump (shunt) type charge controllers+loads (for backup, in case one controller/load fails, the second will keep the batteries from, worst case, catching fire until the first controller is fixed).

    Note: A rectifier is a set of 6 diodes (minimum) between the three phase alternator output (through diodes) to DC battery bus. This stuff is not easy--And you (or your engineer/designer) really need to know what they are doing.

    You could also place a MPPT charge controller + Dump between the wind turbine and the battery bank--MPPT can give you more power (matches V*I from the rectified alternator output to the V*I of the battery bank--sort of like a "variable AC transformer" for DC system). Most horizontal wind turbines need loads 100% of the time, or they will over speed (at normal winds, an unloaded turbine will turn too fast and self destruct).

    Depending on your wind turbine design--There can be other options. For example, some wind turbines are designed to connect to the utility grid (they output 50/60 Hz of AC power). In some cases, you can connect the AC output of the Grid Tied Inverter/Wind Turbine directly to the output of an Off Grid (battery based) AC inverter--When the wind turbine has enough energy it will either share loads with the off grid inverter or even (with some off grid inverters) will even push power "backwards" through the off grid inverter and actually recharge the battery bank--Of course, you need a dump controller (and/or wind turbine control) to stop the charging process (and not damage the battery bank/wind turbine/etc.).

    This is not a small system--Do you have any support from your inverter/turbine/solar installer/manufactures?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #3
    Re: Need wind and solar chargers
    BB. wrote: »
    My first question is the strings of 4 panels and the last string with 3 panels tied into the second to the last 4 panel string. At best, it should not help much. At worse it may damage the top panel in the second to last string.
    I suspect he did that because his combiner only has 12 inputs. He needs to lose those three modules.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Need wind and solar chargers

    i am curious as to what controller you have that takes the vmp of 122.4v at 92.6a imp outputting to a 96v battery bank or is it a case of you are looking for the controllers yet? if looking for controllers then 3 midnite classic 250ks would suffice, but you would have to separate the pvs into 3 separate arrays each feeding their own classic controller. this would be 4 strings of 4 in series for each classic.

    bb is right about the last 3 pvs and these you might just as well disconnect or use them on something else.

    the classic controllers have also been utilized for wind.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Need wind and solar chargers

    You can not use an odd number of panels in any configuration other than all in parallel. This will not work here.

    There is no single controller that will handle 12kW worth of array at any Voltage. At 96 Volts nominal the most you could expect on a single controller would be 7.6 kW, so it would be best to divide the array into two separate units.

    As such you will end up reducing the panels further, or adding one more (26 per controller). With a Vmp of 30.6 and needing an output of 140 from the array to meet charging specs you are limited to two controllers that I can think of: the MidNite Classic 250 or the Xantrex 600 MPPT 80. I am not sure the Xantrex will function for 96 Volts but I believe the MidNite will. Another option would be to divide the battery bank into two 48 Volt segments for charging only, but this necessitates careful isolation of the charging circuit to be sure the negatives/positives of the two never come in contact (may include clipping MOV's from the panel input of the controllers).

    You would need panel strings of five in series for the 96 Volt configuration, three in series for the dual 48 configuration.

    So five parallel strings of five in series would give Vmp of 153 and Imp of 38.4 on an array of 5875 Watts times two for a total of 11,750 Watts. This would be for 96 Volts nominal.

    For dual 48 Volts you would use eight parallel strings of three in series for Vmp 91.8 and Imp 61.44 on an array of 5640 Watts times two for a total of 11,280 Watts.

    You need to consult with MidNite directly regarding configuring a Classic 250 for 96 Volt output or putting two in series for the dual 48 Volt set-up.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #6
    Re: Need wind and solar chargers
    Cariboocoot wrote: »
    You can not use an odd number of panels in any configuration other than all in parallel.

    How about 3x17?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Re: Need wind and solar chargers

    Oh gosh--Back to explaining math word problems to my kids.

    How about "prime numbers" of panels in anything but a single parallel or series string.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #8
    Re: Need wind and solar chargers
    BB. wrote: »
    How about "prime numbers" of panels in anything but a single parallel or series string.

    47 panels in two arrays of 4x5 and 3x9 connected to separate controllers? :D:p

    OP has 51 though.
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