Newbie question regarding solar system



  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    This controller is capable of handling up to 125 Amps of continuous solar power, but open collector voltage should not exceed double the nominal battery voltage. So with that info, can run a third string of two 24v solar panels in parallel? Just to increase amperage.
    Yes, do it.   --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • martinruss7martinruss7 Registered Users Posts: 23 ✭✭
    Hey guys I got what might be a dumb question but I'm going to ask any ways. I noticed my electric meter is reading in KVH Instead of KWH. Is this normal? And accurate or am I at a disadvantage with power company?
  • BB.BB. Super Moderators Posts: 26,980 admin
    Do you mean KVAH (kilo volt*amps*hours)? (note the KVH may be some other marking on the meter that is entirely different than my discussion below--I.e., there is a KVH Industries that makes a lot of different stuff--don't think they make utility meters).

    Most residential meters read in kWH (kilo watt*hours or 1 kWH=1,000 WH). That is a slight advantage for the consumer.

    Many large commercial meters can read (with variations) and bill in kVAH (kilo volt*amp*hours). This is (in many ways) more "fair" to the utility. KVAH is either equal to, or larger than KVWH for the same load(s).

    This turns into a "power factor" discussion (and sometimes into a 15 minute peak kWH or KVAH discussion).
    • kWH = kVAH * Power Factor (see that kVAH is either equal to or greater than kVWH)
    More or less, KWH is the energy you are using. KVAH is the "current" you are using... If you have a lot of motors, "cheap" floresent, arc, mercury, metal halide, LED lighting, or even lots of computers (especially older computers)--Your loads may have "poor power factor"... You are using more current with poor PF loads--And your bill can be upwards of 1/0.65PF=1.54x billing larger than the same loads with a kWH type meter. (note: "good to perfect PF" loads are around 0.95 or near 1.0).

    For large commercial facilities, the utility will charge based on some version of KVAH, and the customer will work do improve their PF (closer to 1.0 PF).

    For homes, it is possible that some "twisty bulbs" (florescent) can have PF as low as 0.5 -- Meaning that they are only 50% efficient in terms of current usage (i.e., instead of using 0.1 amps, they use 0.2 amps for a 120 volt 12 watt bulb). These poor PF bulbs save the consumer a lot of money (i.e., 60 watt filament = 12 watt florescent)... However as far the the utility (and the wiring, distribution transformers, etc.) are concerned, the user is using 24 VA worth of their services, but the customer is only paying for 12 Watts. (i.e., the utility has to supply 2x more current to a poor PF twisty bulb vs a "good PF" twisty bulb--and they cannot sell any more power to anyone else because the poor PF is using "real" current--And the utility only gets pay 1/2 as much money (the utility's fuel cost is still less--because kWH=Fuel usage--However the wiring and transformers are rated in kVAH).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • martinruss7martinruss7 Registered Users Posts: 23 ✭✭
    I had the power company come change the digital smart meter out. And now it reads KWH Instead of KVH and monitor my usage daily on the website, and have seen a 10 kWh drop in usage since change.
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