3 X 250w panels help

alovella Registered Users Posts: 3
edited December 2016 in Solar Beginners Corner #1
I wonder please if someone can help me. I have 3 250watt Solar panels total 750 watts + 300watt wind power. Now, I already have a Hybrid mppt controller. 500w wind & 400w solar 12/24v I currently have 2 12v 120 amp leisure batterys & 12v 600w inverter. My question is. is the Controller to small? & other question is I want to link all panels to turn it into effectively 24v sytem but as i've 3 250w panels. would this effectively then be 36v system? and as i've 2 12v batteries. can I still have my inverter 12v 600w still attached to my batteries? also has a dump load 300w


  • cisco_ken
    cisco_ken Registered Users Posts: 6 ✭✭
    Please give us a little more information on what brands and models of components you are using. If you are using three 12V solar panels in series you have a 36 volt input. Most controllers would have no problem outputting 24V.

  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭

    Hello alovella,  welcome to the Forum.

    Almost all 250 Watt PVs are 60-cell modules.   They have a Vmp of around 30 volts.    They are generally designed for use on Grid-connected systems,  and are neither 12 V,  nor 24 V PVs.

    With a real MPPT Charge Controller (CC),  these can work fine on a 12 V system (system voltage is determined by the battery and inverter voltage.

    So,  you have a 12 V inverter,  so your two 12 V batteries would need to wired in parallel.

    At 12 V,  the "400 watt solar" rating of the CC might mean that it could be rated at about 30 Amps output maximum.  The 12/24 V notation might mean that having PVs rated at about 30 V might well be OK,  if the CC is really an MPPT type.

    On a 12 V system,  with three 60-cell PVs,  you would probably  really need to wire the PVs in parallel,  with circuit protection (circuit breaker or fuse)  on each of the PV.   Customarily this circuit protection would be in a Combiner box,  without knowing the specs on the Hybrid "controller"

    My opinions,    Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.