Upcoming electric bill

MasterjoeMasterjoe Registered Users Posts: 60 ✭✭
So Masterjoe here again with a 4.5 KW solar system.  Checking the production of the system through the latter part of October into November I notice on the best day the system produced 10.7kw  that seems awfully low.  According to PVwatss site I should be in the neighborhood of 16kw accounting for a modest 14% system loss this time of year in our area.  With consumption at roughly say 40-50kw per day we are seriously outconsuming what the pv system is producing.  I have 4 kids I chase after to keep the lights and AC off.  Consequently since this is a battery backup we are not running off the battery bank at night.  So from what i can gather, I have spent thousands of dollars to save maybe $20 on my energy bill.  Also in the event the utility goes down and the panels don't produce even if they do I doubt I would have enough battery backup to last me 12 hours.  Am I missing something here, because I really don't get it?  I know the usage is bad but I expected the system would produce more than it is.  I read so many stories about people with an electric bill near zero.  Is this really fathomable?  The way it is now we produce 200-500 watts more for 4 hours a day.  The rest of the time we are pulling from the grid.  From Oct 14 - Oct 31 we produced 137.2kw and Nov 1 - Nov 6 36.7kw.  The inverter is running its charge cycle early in the mornings from the grid as well.  I appreciate the patient explanation on a wondering mind, be gentle lol.
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

  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭
    There are much better people to answer grid tie systems...

    Depending on how your system is set up, you may  only be seeing the extra energy created over what you are using. So your 'extra' wattage may be hidden in your usage that wasn't drawn from the grid.

    I have no idea, where you are located, but this time of year is the worse for much of the country. Between short days and slow moving fronts that make areas cloudy for days for days on end. About 3 years a go in Central Missouri, we had 13 days with just a single hour of direct sunlight!

    I PVwatts uses an average solar insolation over many years. This time of year things can vary hugely! The return will be slow and steady, you are in the worse time of year for return on your investment.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • mcgivormcgivor Registered Users Posts: 1,281 ✭✭✭✭
    edited November 7 #3
    The hours of sunlight drop off in November, for Petersburg VA, where I think you are located,  the angle of the panels, if fixed on a roof may not be at optimum angle which will further reduce production the link below will provide the best angle, direction is also part of the equation, other than location I've no information other than knowing there is reduced hours, the 4.5KW array would more than likely produce ~80% of rated figures at best or 3.6Kw, assuming 3 hours sun is about 10Kwh. Enter the information using the calculator and post the results. The stories about almost zero bills is relevant only if all data is disclosed, size of array daily consumption, cost of energy etcetera , so the return on investment will vary, depending on this, energy conservation would probably cost less to achieve more, unless the feed in tariff is very generous.
    http://solarelectricityhandbook.com/solar-irradiance.html
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Raj174Raj174 Solar Expert Posts: 461 ✭✭✭✭
    @Masterjoe
    Since you are probably load shaving, (I don't think the SW will sell to the grid) and not cycling your batteries to any depth, then PV production will be limited to the amount of power the loads consume during the time of production. This should vary with the weather and battery SOC. It could be a good bit less than the PVwatts estimate. Also, I would think that your system would work like a normal off grid system if you lost the grid. By the way, I have a similar backup system, but a bit smaller array, however I cycle my batteries fairly deeply and I average about 10 kWhs per day.

    Rick 
    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 195AH HI Power LiFePO4 no BMS, 4000W gen.
  • mcgivormcgivor Registered Users Posts: 1,281 ✭✭✭✭
    Raj174 said:
    @Masterjoe
    Since you are probably load shaving, (I don't think the SW will sell to the grid) and not cycling your batteries to any depth, then PV production will be limited to the amount of power the loads consume during the time of production. This should vary with the weather and battery SOC. It could be a good bit less than the PVwatts estimate. Also, I would think that your system would work like a normal off grid system if you lost the grid. By the way, I have a similar backup system, but a bit smaller array, however I cycle my batteries fairly deeply and I average about 10 kWhs per day.

    Rick 
    Rick, It's an XW I'm the SW
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Raj174Raj174 Solar Expert Posts: 461 ✭✭✭✭
    @mcgivor
    Thanks for the correction, I wasn't aware that Xantrex made a 4000 watt XW series inverter. I guess lower production is due to reduced solar hours, but you would think that PVwatts would reflect that.
    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 195AH HI Power LiFePO4 no BMS, 4000W gen.
  • EstragonEstragon Registered Users Posts: 1,545 ✭✭✭✭
    Just a thought, but as well as potentially not being at optimal angle to the low sun, it may be worth checking to see if any shade issues have cropped up. Even seemingly minor shading from a wire, small bare branch, antenna, etc can have a major effect. Might also be worth checking for bird bombs.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • westbranchwestbranch Solar Expert Posts: 4,860 ✭✭✭✭
    Low sun right now, it is only going to get worse from now to ~Jan1, then the sun starts to pick up, barring clouds...  So if you can, optimize the Array angle for the winter. Next I would do a shading survey, every half hour...  You do NOT want ANY shade across any of the panels, especially if series connected... Let us know how the array is wired and the survey results, It may be time to start the chainsaw. as others have said, if the CC is reporting the amount of power stored in the batteries, that is all you used from the previous day,  in kWhr not KW.
    kW is an instantaneous reading.
    What was your consumption , in kWhr, before you installed your system?  What has it been since? compare the same months in different years is useful as opposed to 'over the summer' etc.
    hth
     
    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, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
Sign In or Register to comment.