Fuses going out

MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
One of the fuses on our solar array was almost bad as the installer said.  Replaced the fuse and the system was humming along again.  The very next day I have now production from the array again.  Does anyone know why this would be?
4.5kw 24v System
18 Solartec 250w polycrystalline panels
Xantrex XW4024 Inverter/Charger
Conext MPPT 80-600 Charge Controller
12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    It does depend on the fuse type and holder... And the rating of the fuse. What are your fuses?

    We have seen "car type" fuse holders that have failed when running at much less than the holder's maximum rating--Continuous current flow in hot air/under sunlight, and the holders (and fuses) can fail.

    Fuses are also designed to be "unreliable"--I.e., they blow if carrying rated current... Not like the rest of our wiring, connectors, and fuses, which are designed to work at rated voltage/current without problems.

    We typically use 1.25x max continuous current rating (i.e., a 12 amp current flow with 15 amp rated fuse/breaker) to help reduce the chances of a nuisance trip (for fuses and wiring that comply with NEC).

    Also, things like moisture can get in, corrode a connection (or fuse internals), and cause early life failure too (as well as normal thermal cycling, shock and vibration, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    They are KLKD 15 600v AC/DC Littlefuse
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,180 ✭✭✭✭✭
    How many strings on the mppt-80? Look at it's home screen and what is the PV input voltage  & current during bulk?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Everything looks OK with the fuse selection, assuming that your max continuous current does not exceed (15 amps * 0.80 NEC derating=) ~12 Amps.

    There is a nice data sheet for this fuse family:

    https://www.littelfuse.com/~/media/electrical/datasheets/fuses/industrial-and-ul-fuses/littelfuse_fuse_klkd_datasheet.pdf

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • pdhpdh Registered Users Posts: 30 ✭✭
    > One of the fuses on our solar array was almost bad as the installer said.

    Did the installer tell you how he knew the fuse was going bad? Maybe he saw physical damage, or a bad connection, or corrosion; or maybe he measured its resistance and saw a high value? It sounds like he must have noticed something "not quite right," it would be helpful to know what that was.

  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    I'd love to know too PDH, but I was at work.  Now that we are having the same issue he's trying to convince me its something im doing in the settings.  Like when he accused me of pushing buttons then told me he had to reset all the settings again so he could charge me for it.  What the hell good is a warranty.  Its really a joke and as soon as we get some money im getting a standbye generator.
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,180 ✭✭✭✭✭
    You really need to understand everything yourself. The installer is just a means to get it done faster without you doing the work.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    Pv In power is 56w at 300v .2 amps  I dont even see bulk and absorption stages anymore. This system has been down more than its been up over the last 4 years.
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    well im fighting with my installer now.  He is telling me the inverter is supposed to be reading all zeroes because the batteries are full.  Am I supposed to assume for the rest of the day we will draw all our power in from the utility?  I need someone to explain to me how a hybrid system with battery backup is supposed to work.  They also tell me our 18 kw from our array is being split between supplying the batteries and powering the house.  So on the SCP when I read harvested 8KW does that mean total array production or what went back to the utility?
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    I feel I have been lied to about this system.  I did not pay $26,000 to babysit 12 fully powered batteries until I need them and get no other benefit out of the system.  Who in the hell is stupid enough to do that.  My electric bill has never changed in 4 freaking years.  I am pissed off.
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • MasterjoeMasterjoe Registered Users Posts: 83 ✭✭
    They claim the main function of a hybrid with battery backup is those batteries.  So once those batteries are full thats it.  All the my power consumption in the home is coming from the utility.
    4.5kw 24v System
    18 Solartec 250w polycrystalline panels
    Xantrex XW4024 Inverter/Charger
    Conext MPPT 80-600 Charge Controller
    12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    A hybrid system can do Grid Tied operation. But it has to be programmed to do this, and you have to get the approval of your utility (and usually have a building permit / inspection for your system too).

    If your system is approved for GT operation and programmed correctly, then the solar array should be outputting 100% of its available energy to the charge controller... And the charge controller should be in MPPT mode and outputting the maximum current/energy to the "battery bus". At that point, the GT Inverter should be holding the battery voltage (say at 54.4) volts... Some current will be going to the battery bank (around 0.01% to 1.0% depending on battery type, temperature, age of battery bank, etc.) and "siphoning" off the extra current (over and above charging the battery bank) and "invertering" that energy and feeding it to your main panel. At that point, effectively, the energy is used to feed your home loads, and any power that exceeds your home loads is feed backwards through your utility meter (the proper meter from the utility for Grid Tied power systems).

    It is also possible to program your GT inverter to feed local AC loads (and charge the battery bank), and not feed energy backwards through your energy meter. If there is more power from your array than needed by your battery bank + local loads, then the MPPT controller will cut back on the power harvested from the solar array, and keep the battery bank at 54.4 volts (note that it appears that some/many/most(?) hybrid systems will still consume around ~2 amps from the utilty (2a*240v=480watts) to avoid illegally "backfeeding" energy to the utility--simply a design choice/limitation).

    And there is running the system in pure backup mode. The inverter feeds power from the grid, keeps the battery charged, and does (almost) nothing with the energy from the solar array until the AC mains goes away. At that point, the inverter disconnects from the (dead) utility power and fees your home loads.

    Was your system (usually) installed with building permit and your utility contacted (and typically your meter changed) to support "net metering" on your bill? If the first two are done, then it sounds like your hybrid inverter needs to be programmed for net metered system.

    And even then, there are variations... You could program to feed the utility only the excess power from the solar array (typical "GT solar" system). Or it could even use your battery bank at night to power your loads... The feed your loads at night is harder on the battery bank (cycling the batteries) and less efficient (again, cycling batteries). But may make sense depending on your rate plan (my utility charges very high rates from ~1pm to ~9pm--So, feeding from the battery bank in the evening could save me money (my system is a pure GT solar, no battery bank, so I could not do that anyway).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,180 ✭✭✭✭✭
    So sad. Along with Bill's questions my comment is the XW4024 has been obsolete and not sold new for over 8 years now.
    Did the installation company sell you a used one on this 4 year old system?

    Your questions are hard to answer as I do not know what your level of understanding is here. You need to deal with the installation company and be positive. If you are not you will really be on your own.

    The one question you asked is about Harvest. It is the amount of power that the charge controller produced. It does not mean it went to the utility. The number you posted is low for a system with this much solar. 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • mcgivormcgivor Solar Expert Posts: 3,401 ✭✭✭✭✭
    @Masterjoe you need to take a deep breath and relax, understandably it is frustrating, normally a hybrid system would use excess energy to support loads before selling to the grid. There are many possible settings which would optimize where energy is directed. Being at the mercy of an installer, who may, or may not have your best interests in mind, only compounds the uncertainty.

    Using the SCP it is possible to review the basic settings, which would be helpful, advanced settings need a certain input sequence which is in the manual, can't remember offhand but will elaborate if needed after reference to the manual. The possibility is the installer has purposely restricted you because they are in the business of making money not friends, just being cynical of course. The advanced settings is where the true functions will be revealed, so pause, rewind and start from the beginning. What access  do you have currently? 


    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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