Solar solar power system in India questions

BB.
BB. Super Moderators, Administrators Posts: 33,613 admin
in Off Grid Solar & Battery Systems #1
This discussion was created from comments split from: Turn off solar panels???.
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #2
    Hi,
         I have one problem.I want to install a off grid system of 10 kw in a school.if a school is leave for about two weeks. i have to shut down the power coming from solar panel. is there any way to shut down it

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #3
    sridharTS said:
    Hi,
         I have one problem.I want to install a off grid system of 10 kw in a school.if a school is leave for about two weeks. i have to shut down the power coming from solar panel. is there any way to shut down it

    Other than covering it, there is no way to keep a solar panel from having a voltage on its output, even when it is not being used.
    You can open the disconnect or fuse so that the power does not reach the GTI or Charge Controller. Or you can make sure there is zero voltage on the output by shorting out the output leads. That will not hurt the panels and output power will be zero even though current is flowing.
    NOTE: Short out the panels, not the batteries!!!! :smile: 
    SMA SB 3000, old BP panels.
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #4
    Covering the panels would decrease the module efficiently.
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #5
    I have made some calculation based on energy needs. needed is 9000w, 64500watt hr.
    i have selected 10kw inverter 120v/240vac. my battery capaacity based on 64500 watthr , 48 volt system i need around 2v,1800ah capacity.
    solar array size :sunlight 6 hrs 10.8kw. i have choosen 300watt panel. 39v,9.42 amps
    charger controller size is around 240 amps. so i have choosen 3 x 8o amps,150v mmpt charge controller.
    In one string 3 panels are connected in series there, for one charger controller 4 strings needed. connected 4 strings in parallel so get 117v , 37.68amps.

    i have splited 3 charger controllers. so how can i wire the batteries to i for charge controllers. or any higher amps charger controller is there above 80amps i.e.,240amps
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Wiring the batteries in series/parallel connection:

    http://smartgauge.co.uk/smartgauge.html
     
    I am not quite sure I understand all of your questions here... In general, you would let the solar charge controller manage the batteries even if there are no loads (i.e., when there is nobody there).

    Normally, if you need to shut the array down--As said above, you would just disconnect the leads from the array (usually using the protective circuit breakers).

    In any case, there is a lot of details on designing and wiring the system to ensure you have a safe and reliable power system... Plus you will need tools (hydrometer, DC current clamp digital multi-meter, etc.) and a source of distilled water. And a reliable maintenance person to keep an eye on the system (daily checks when first installed, once ever several weeks at least when the system is stable).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #7
    The three arrays feed three seperate charge controllers, which feeds the common DC bus, which both battery bank and inverter are also connected to. All with overcurrent cirsuit protection. However if you need to ask this i think you need some help because a system that size requires an experienced designer and installer.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    When the school is vacant, you can use the solar harvest to distill water !
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #9
    Is 10 kw off grid inverter is there. OR we want to buy 3kw x 3 and 1 kw to combine 10 kw

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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #10
    Is there any manufacturers  of 10kw inverter

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #11
    sridharTS said:
    Is there any manufacturers  of 10kw inverter

    Even with a 48v battery bank, 10kW would be a current over 200A DC. That is difficult to wire up safely, so it is more likely that the maximum inverter size readily available would be more like 5kW.

    Now UPS units are available rated at 10kW and higher, but their standard battery banks are typically 100V or higher. In some cases over 200V.
    SMA SB 3000, old BP panels.
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #12
    What will happen if the battery is not used in off grid system. also without grid.
    that means solar power is combined in the combiner and sent to the inverter and to the utility loads.

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #13
    sridharTS said:
    What will happen if the battery is not used in off grid system. also without grid.
    that means solar power is combined in the combiner and sent to the inverter and to the utility loads.

    The solar output is DC at a near constant voltage and varying current. You cannot send that DC directly to loads. You have to send it to the grid connection using a grid tie inverter (which only works when the grid is up) or send it to batteries and an off=grid inverter whose output goes only to the selected loads that need to run when the grid is down.
    SMA SB 3000, old BP panels.
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #14
    Thank you

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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #15
    This is my setup going to install in a school is there any thing to be added to my system
     10.8 kw panel installation. using 300 watt panel. using 80 amps three charger controller, 10 kw single phase inverter. battery bank is 2v,1800ah capacity connected in series with 24 battery to get 48v,1800 ah  .
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  • sridharTS
    sridharTS Registered Users Posts: 33 ✭
    #16
    Can any one reply

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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #17
    I DO believe your question was answered and there was a question to you that we are waiting on an answer to.....
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #18
    Can you re-write/copy and paste the question(s) you want answered.

    I just want to be sure--You understand the difference between a 10 kWatt inverter and and 40 kWatt*Hours of battery storage?

    10 kWatt is the rate of energy usage (like 10 liters per hour of diesel fuel for a genset).

    And 40 kWatt*Hours is the amount of energy used (like having a 40 liter fuel tank).

    You size the inverter to power the loads you have turned on at once (i.e., 10 classrooms * 200 Watts = 2,000 Watts = 2 kWatt), vs running 2,000 watts * 6 hours per day = 12,000 kWatt*Hours per day.

    In general, you need to understand your loads and make them as small as practical... Conservation (changing to LED lighting, small/laptop computers/turning lights off during sunny weather, etc.) is going to cost you much less, overall, vs just building out a larger solar power system.

    In the US, off grid solar power costs ~5-10x the cost of utility power.... And is similar in $$$/kWatt*Hour costs as running a genset (taking equipment costs, replacing batteries every 5-8 years, replacing inverters/charge controller every 10+ years, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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