First electric bill

MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
edited November 30 in Solar Beginners Corner #1
Hello all got our first utility bill in.  From this time last year we used roughly the same amount of power and saved a whopping $14 off our electric bill.  Yes I spent thousands of dollars to do that lol.  The system produced 143kwh and 51kwh was credited on our utility bill.  Does that sound about right for a 4.5kw system?  We run around 1350kwh a month or more and use the AC/heater and have the water heater on all the time as well.  Could this be the biggest culprits as to why I am not seeing any energy savings?  In the main breaker box we have the hot water heater, the AC unit, dryer and stove.  In the subpanel all the receptacles, washer, lights and well.  So I want to check a few things here to verify this is normal.  So at night we run around 350watts of power which I gather is coming from the batteries since the voltage drops through the night, but it seems to drop about .3v an hour?  At that rate I don't think I would ever have 3 days worth of autonomy on the batteries.  Now a tech at Schneider said the Grid helps to support the batteries in running the loads.  Exactly how much and what items would the grid help support.  I would think all the items in the sub panel would be charged from the batteries and the main panel from the grid?  The recharge volts for the CC and the inverter is 25v.  What I am noticing is before the voltage even gets to 25v like to 25.8v the inverter kicks in to give the battery bank a 10 minute or so bulk/absorption charge to anywhere from 26.3-27.1v depending on the day it is never consistent.  Also the inverter is giving this charge more than once per night.  Last night at 10:00pm, 12:30am and sometime before 6:00am.  Is this normal and if so why?  I am not understanding why recharge volts are not being reached.  Have an XW4024 Hybrid inverter/charger on a 24v system.  Thank you all for your help, patience and understanding.
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

  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    143kwh sounds a bit low, but depending on location, low sun angle, short days, and/or gloomy weather at this time of year can really impact production.

    25v seems a bit high to me, but I also wonder if there is a delay setting that might need to be made a bit longer. Something like a pump coming on might pull voltage down for a few seconds, maybe long enough to trigger a rebulk?

    I'm not well acquainted with that inverter, so others may be of more help with that. With most inverters, etc., it often takes a bit of fiddling with settings to get things working best for your specific situation.
    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
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    Voltage drop, You are seeing .3 volts, though you don't tell us the system voltage, I will assume by your settings it's a 24 volt system. So where are you beginning to see the .3 volts? Normally a 24 volt battery banks resting voltage would be 25.4 volts, if you are measuring a .3 voltage drop per hour, that would be about 4 volts over the night. I suspect you are starting from the charging voltage which must be@15% higher to get the current to flow nicely from high to low.

    Perhaps starting a thread on how to maximize your selling wattage. Basically hybrid systems are hard to make cost effective, you have extra cost and power drain of batteries. If you keep the batteries primarily in float and just sell only, not try to shift the usage to a cheaper per Kwh rate (if indeed that is why you are using the battery at night) It will be the best return on investment. You will want to cycle your batteries some but once or twice a month to 80% SOC might be all they need.
    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.
  • dennis461dennis461 Registered Users Posts: 85 ✭✭
    Masterjoe said:
    .....  The system produced 143kwh and 51kwh was credited on our utility bill.  Does that sound about right for a 4.5kw system? 
    .....
     
    You need to clarify some things, did the system produce 143kwh in a day, a month or a year?
    Your post started talking about ,"From this time last year we used..."
    Also, how does your utility allow surplus generation.. my utility will credit me for 100% of excess generation sent to the grid.  Not all utilities allow this
    Camden County, NJ, USA
    19 SW285 panels
    SE5000 inverter
    grid tied
  • WaterWheelWaterWheel Registered Users Posts: 242 ✭✭✭
    edited November 30 #5
    I went through the same learning process.      You can fine tune these numbers.

    Grid support is the battery voltage where the grid starts supplementing the batteries.     Keep in mind that a large load suddenly cutting in will dip battery voltage so I'd suggest setting grid support around 24.6v.      That way light loads will stay on the batteries, even if the batteries are 85% SOC but when the hot water heater kicks in the grid will carry most if not all of the load.       Then when the heavy load ends if the batteries are fairly well charged the grid power will be cut off automatically as you only draw a small wattage.

    During times of fully charged batteries my mini-split can kick in at night slowly ramping up to 1400 watts and the grid support won't kick in.       But if the batteries are only at say 90% SOC the additional load will start the grid support protecting the batteries.

    Since you're hooked to the grid full time I'd conceder disabling the automatic grid charger and set the low battery cutout around 24.2v with the LBCO (low battery cut out) Delay set around 300 seconds.        The 300 second delay will keep and large loads (well pump) from triggering the battery cut out.      But this is a mute point when grid support is enabled and the grid is working.      That charger uses a lot of grid electricity to top off those batteries; this is because the batteries are not as efficient at absorbing the power during charging the last 15% of the charging.       I'd suggest only using the charger if the batteries haven't gotten to at least 95% SOC (using SG meter to measure) in the last 5 days.       Let the panels do their job and the grid cover the rest.

    Final thought,      Don't depend on a SOC meter too heavily, they tend to drift off.     SG (specific gravity) meters are the only accurate way to know a battery's true SOC (state of charge).    Measuring the SOC by voltage when there has been a load on the batteries in the previous 3-5 hours isn't very accurate    If you haven't already get and use a SG meter.      Also since you have 3 strings using a clamp type amp meter that can read DC current is very helpful in determining that all 3 strings are charging/discharging at an equal pace.

    These are all hard lessons I've learned the hard way.

    Conext XW6848 with PDP, SCP, 80/600 controller, and conext battery monitor

    18 SW280 panels on Schletter ground mount

    48v 790 amp/hr Crown battery bank

  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    Sorry Dennis, the system produced 137.2 kwh in the month of Oct. We have 18 250w panels on 2 strings of 9 and 12 6v batteries connected in 3 strings of 4 to make a 24v bank. We get 100% credit from our utility as well. The utility received 51 kwh from our system and it came off our 1377kwh of usage bringing it to 1326kwh. Comparing Nov 16 usage 1293kwh to Nov 17 1326kwh usage we increased 33kwh. In 2016 the system was not operational. That is why i don't for the life of me understand what i spent thousands of dollars for.

    Photowhit: the .3 is coming from the system voltage starting at 26.3. In an hour or so it dropped to 25.8 when the charger on the inverter kicked in to 123amps 30.1v and absorption charged the bank for roughly 10 minutes with the amperage and voltage dropping off until it reach 16 when it switched back to acpassthru and the bank showed full on the system control panel display and the battery bank settled to 26.8v and then he cycle repeats itself etc. etc. Not consistent every night as it seems whatever the voltage is when it begins and ends. I would love to maximize my selling wattage however it seems by pv array cant seem to produce a whole lot. I don't know what a 4.5kw system in November should be producing per day but with the 24v system and one CC we are getting around 7.9-8.7kwh a day on a good day. My installer will not upgrade us to a 48v system as he says i'd need 4 more batteries and 6 more panels and the cost outweighs the benefit i'd receive. I dont know how true that is. He will not add a second CC for us as he also says we don't need it. The installer states they have never set up a hybrid system to be just a battery backup.

    Waterwheel: One thing I noticed last night while watching the system control panel when the heater kicked on is that the wattage it was using was not registering on the SCP. We have 2 electric panels in the main panel we have the AC disconnect, heater, hotwater, dryer, outside AC and furnace fan all on the grid. In the sub panel connected to the batteries we have receptacles, well, microwave, dishwasher and lights. So none of the appliances in the main panel show up on the SCP. So I take it they run strictly off the grid?

    The charger on the inverter is set to 300 seconds with absorption set at 180 minutes. I assume that is why I see the inverter charging the battery bank as oftne as it does to get its 180 minute absorption in? Would it make more sense for me to set the charger to disable in the SCP? The LBCO is set to 22v with recharge volts at 25v. Grid support volts is set at 32v this has been found beneficial for the batteries as the inverter has what is Enhanced Interactive mode where the voltage is tracked through all 3 charging cycles ensuring the batteries receive a full charge and maximizing the use of the pv array and improving the state of health of the batteries.
    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
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    Masterjoe said:
    Photowhit: the .3 is coming from the system voltage starting at 26.3. In an hour or so it dropped to 25.8 when the charger on the inverter kicked in to 123amps 30.1v and absorption charged the bank for roughly 10 minutes with the amperage and voltage dropping off until it reach 16 when it switched back to acpassthru and the bank showed full on the system control panel display and the battery bank settled to 26.8v and then he cycle repeats itself etc. etc. Not consistent every night as it seems whatever the voltage is when it begins and ends. I would love to maximize my selling wattage however it seems by pv array cant seem to produce a whole lot.
    Listen and investigate your settings! A 24 volt lead acid battery bank WILL NOT MAINTAIN 26.3 volts! THIS IS A BAD SETTING!

    At rest a lead acid battery FULLY CHARGED will only have a little over 2.1 volts per cell. a 24 volt battery has 12 cells giving a fully charged resting battery a voltage of 25.2 volts (really about 25.4). Change this setting to something more realistic or you will continue this cycle. I would use no more than 25.4 volts and that would still cycle often. I would suggest something near 80-85% SOC or around 25 volts. I don't deal with these hybrid systems, but maintaining fully charged isn't a good idea, you want them to cycle a bit.

    YOu are in the worse part of the year for solar in the northern hemisphere. I don't have your location, but check your solar insolation numbers for your area. In Columbia Missouri, near where I live It shows an average of 3.6 hours in Nov and 3.2 in Nov, for fixed solar arrays properly angled (oriented south with angle = latitude) It also shows that during the 30 years it is based on a high and low of 2.4 and 4.9 hours for Nov and 2.2 and 4.4 for Dec. along with Jan these are the shortest days of the year. If you had a 4.5 Kw array set up here, you could expect about 4500w (array) x .75 (NOCT value) x 3.6 hours per day x 31 days or 376 Kwhs so I do think there is some cause for concern.

    I would think in a system setup for solar/battery energy first, that the energy you use during the day is NOT registered at the meter, the would explain the discrepancy. The incoming energy is used by the inverter to supply the loads present at the house and the meter would not see these loads. The loads require no grid energy to be supplied so would not be recorded. It may be that you are using more energy this year than last. It may be colder, or your use patterns might have changed.
    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.
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    Masterjoe said:
    I would love to maximize my selling wattage however it seems by pv array cant seem to produce a whole lot. I don't know what a 4.5kw system in November should be producing per day but with the 24v system and one CC we are getting around 7.9-8.7kwh a day on a good day. My installer will not upgrade us to a 48v system as he says i'd need 4 more batteries and 6 more panels and the cost outweighs the benefit i'd receive. I dont know how true that is. He will not add a second CC for us as he also says we don't need it. The installer states they have never set up a hybrid system to be just a battery backup.
    Sorry, Now I recall the thread on a single charge controller. THEY COMPANY IS WRONG! IF YOUR ARRAY can produce 4500 watts x .75 or 3375 watts normally (and MORE during these cold months!) and you have an 80 amp charge controller and a 24 volt system. 

    Ask them how you array's 3375 watts of power incoming at a float voltage of 27.2 volts can produce full wattage through an 80 amp charge controller? Because 3375watts/27.2 volts = 124amps. Ask them this question. 

    If you want to ask them about a nice cold clear day when your array is producing near 4500 watts and if the support voltage is actually the float voltage at 26.8 volts it gets even worse! 4500/26.8=168 amps. Your single charge controller isn't going to handle either...

    Perhaps they are use to setting up 48 volt systems and just don't understand this problem.  

    ...or perhaps they are idiots!

    If you ask them this question, I would hope a light bulb would click on in their head. If not refer to above.

    Go to them fast! If they don't understand the nature of the problem they aren't likely to be in business too long. You want to get your case settled before they go bankrupt!

    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.
  • Raj174Raj174 Solar Expert Posts: 477 ✭✭✭✭
    edited December 1 #9
    " Grid support volts is set at 32v this has been found beneficial for the batteries as the inverter has what is Enhanced Interactive mode where the voltage is tracked through all 3 charging cycles ensuring the batteries receive a full charge and maximizing the use of the pv array and improving the state of health of the batteries."

    Looks to me like the grid support voltage at 32V is set much too high and is restricting production. How often and for how long do you think the battery voltage is above 32V? 
    This is from the manual page 3-17:

    Important: To allow Grid Support to function after battery charging has completed, it is recommended to set the Charge Cycle to 2-Stage. After completing the absorption charger stage the XW Inverter/Charger checks whether battery voltage is above the Grid Support Volts setting. If battery voltage is above the Grid Support Volts setting, the XW Inverter/Charger uses available DC power to support the loads. See “Charger Settings Menu” on page 3–10.

    Turning the charger off also enables Grid Support functionality.

    If the Charge Cycle is set to 3-Stage, the Grid Support Volts setting must be higher than the float voltage setting for your battery type for Grid Support settings to function (see “Custom Battery Menu” on page B–4 for default Float voltage settings).

    Important: Upon startup, the XW Inverter/Charger does not enable Grid Support functions for five minutes. During this five-minute period the XW Inverter/Charger determines whether the utility grid voltage and frequency are stable and within nominal range. For more information, see “Islanding Protection” on page 1–5.

    Table 3-6 Grid Support Settings menu

    Grid Supp Volts

    Sets the level to which the batteries will be discharged when the inverter is selling power to the grid or supporting the power grid by providing additional power to the loads. This setting is not adjusted for the battery temperature if the temperature sensor is installed.

    Sell

    Turns Sell mode on and off. When Sell is enabled, the XW Inverter/Charger AC output is divided between powering loads and delivering power to the utility grid. Sell mode requires the battery voltage to be above the Grid Support Volts. 

    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.
  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    Rah: what would be better setting inverter/charger to disable or setting grid support volts below battery voltage and if so on a 24v system what would the best voltage number be? Right now with battery temp at 51 degrees the inverter charger charged the bank to 27.3v at 7:30pm. Loads are around 850 watts
    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
  • Raj174Raj174 Solar Expert Posts: 477 ✭✭✭✭
    First a couple of questions. Are you trying to support your loads from the batteries and the grid after the sun is down? 
    Are you trying to maintain a full battery for backup purposes? If the answer is yes to both questions then in my opinion, I think the grid support voltage should be set just above float voltage. The lower the setting the more you will get out of the batteries. If it were me though, I would dig a little deeper with a lower voltage, taking the battery down to 80 to 85% SOC. In the extract from the manual it states: "If the Charge Cycle is set to 3-Stage, the Grid Support Volts setting must be higher than the float voltage setting for your battery type for Grid Support settings to function (see “Custom Battery Menu” on page B–4 for default Float voltage settings)". With this setting, hopefully, the charger will stop charging the batteries using the grid from sundown to sun up because when the battery voltage drops to grid support voltage self consumption should stop. 
    I do agree with Photowhit, that these batteries should be cycled, it is good for them. Especially for the first few months of plate formation. I believe that if you experiment a little with the grid support voltage you will not only learn a lot about your system, but also discover the optimal setting (highest consistent production) you're looking for. Make a small change in grid support voltage, record it and look at the results, make another adjustment and so on. Have fun, you won't break it.
     
    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.
  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    Thank you very much Rick I’ll give it a shot and get back with the results in the future.
    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: 69 ✭✭
    edited December 2 #13
    Forgive me for being a bit confused Rick.  The Charge Controller is a 3-stage charging system so I would keep grid support volts above float voltage say 27.5v.  The inverter is a 2-stage no float, so should i begin experimenting with the same 27.5v and then go lower on the inverter only?  The inverter/charger seems to want to keep the batteries charged to 26.3-27.3v from sundown to sunup.  
    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
  • mcgivormcgivor Registered Users Posts: 1,304 ✭✭✭✭
    edited December 2 #14
    Masterjoe said:
    Forgive me for being a bit confused Rick.  The Charge Controller is a 3-stage charging system so I would keep grid support volts above float voltage say 27.5v.  The inverter is a 2-stage no float, so should i begin experimenting with the same 27.5v and then go lower on the inverter only?  The inverter/charger seems to want to keep the batteries charged to 26.3-27.3v from sundown to sunup.  

    If I've followed correctly, the system is a grid tied/supported hybrid, the XW inverter charger has many features which could be used to maximize efficiency, from the sounds of it, they are not being utilized to achieve this. Having a battery for the sake of backup during an outage is, in my opinion, a waste, use it or loose it, within reason of course, stay within the top 75% of the battery capacity. This can be achieved in various ways, one of which is load shaving, especially benificial if peak billing is a factor, if not the load shaving could be programmed to support the grid overnight, for example, the percentage of which would be dependent on loads. You say the inverter charger is 2 stage, no float, is it programed this way? because from my understanding it can provide float, if nèded, but in your case it would be logical not to float overnight with grid charging, but rather use some of the battery capacity, as mentioned previously.  Autonomy was mentioned, this is generally a concern off grid, unless the grid is notoriously unreliable, as in frequent outages lasting days, it would be better to use the battery if this is not the case. Obviously I'm not in your situation, but I've done a lot of thinking lately using grid support, in anticipation of connecting to the grid in the near future, which is unreliable, so a generator is in the picture, already purchased. Naturally it's easy to be an armchair quarterback, so to speak, but getting things into perspective is an important first step. 
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Raj174Raj174 Solar Expert Posts: 477 ✭✭✭✭
    As @Photowhit said, the battery is full at 25.4V, so setting the support volts setting just above this might be a good place to start. I would also set the inverter/charger recharge setting just below this, maybe 25V. I don't see any benefit in charging from the grid then turn around and use the batteries to supply power to the loads the same night. Try it and see if the battery voltage stays above the charger recharge voltage setting for the night. 

    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.
  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    I wonder if the voltage being taken above 26.3 is temperature compensated since the battery temperature at the time of occurence was 44 degrees. 2 years ago the CC went down. At the time we had no money to replace it and I am certain my installer enabled the charger on the inverter so we could get some mediocre benefit I guess. When the CC was installed the charger was never disabled. I would like to disable the charger first and see how we run on the overnight and see if the system stays above recharge 25 volts and then adjust from there. Any thoughts?
    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
  • Raj174Raj174 Solar Expert Posts: 477 ✭✭✭✭
    Keep in mind, the grid support volts setting is not temperature compensated.
    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.
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    I don't care for how your system is setup as discussed in the 24 vs 48 thread. Hybrid systems are expensive to begin with and you are hampered by the 'choke' of a 80 amp charge controller.

    I think you should get a professional opinion from someone, It would be worth $100 to ask some one who can evaluate your system and give you a proper diagnosis. Wish I knew more about grid tied hybrid systems, but I can see problems.

    If there is a complete description of your setup somewhere that you could just ask for suggestions as to, corrective equipment and proper settings. it would be money well spent.

    I think @Dave Angelini may have setup some systems to sell to the grid, but otherwise you are just getting replies from other users who have setup a handful of systems.

    Certainly in direct sunlight the single 80 amp charge controller is limiting your production and ability to sell back to the grid by a substantial amount. At float roughly 44 amps at 24 volts or roughly 1Kw per hour around solar noon. @WaterWheel and @Raj174 both have similar systems but are running at 48 volts.

    Did the installer give you an information sheet on your system before they installed it? Perhaps you can look at it and see if they did a forecast of return on investment or expected sell totals to the electric company. 
    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.
  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    edited December 2 #19
    Thank you Photowhit I do definitely plan on getting someone to look at it. Their inverter can also be set to 3 stage as well. The installer told me from the beginning I would produce enough to power my house and enough for my neighbor too. He also keeps telling me all I do is skim off the top of the batteries at night. I’m pretty sure in our last conversation he also said they never installed a hybrid with battery backup before. All comforting things lol. My installer is not answering my calls anymore and I might be calling channel 12 problem solvers. I appreciate the help from everyone.
    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: 69 ✭✭
    edited December 2 #20
    Dumbest question of all I suppose is how do I even know if i am using the batteries.  I have here what the meters on the XW4024 is reading: 

    Status;  acpassthru
    AC1: -1787w fluctuating
    AC1 in L1:  -13.3a 123v
    AC1 in L2:  -10.1a 123v
    AC freq:  60.0hz
    Load L1: 4.2a 124v fluctuating
    Load L2: 9.9a 124v fluctuating
    DC: 0.0a 26.1v

    I have to guess since dc amps is 0 we are not using the batteries and they are instead self discharging at 51 degrees?

    In our Power Distribution Panel we have:

    Inv 1 in Grid: On
    Grid Bypass: Off
    Inv 1 out Acloads: On

    I am wondering if these were ever switched back over when the new CC was installed?
    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
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    I think you will need to give us a time of day with the numbers. 26.1 volts DC, is more than fully charged, if it's just after dusk, it's the 'surface charge' coming off the batteries. During the day they will be held at a high enough voltage so that they won't discharge with loads starting, usually around 27.2 for off grid systems. This isn't high enough for meaningful charging, but with a load starting it will allow the charge controllers to kick in and allow more current from the solar array rather than drawing from the battery bank. Over night even without a load the battery bank measured voltage will naturally settle to around 25.4 volts...
    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.
  • MasterjoeMasterjoe Registered Users Posts: 69 ✭✭
    edited December 3 #22
    Anyone know how I would set my system to invert from the batteries at night and not use grid power?
    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
  • PhotowhitPhotowhit Solar Expert Posts: 4,280 ✭✭✭✭
    Masterjoe said:
    Anyone know how I would set my system to invert from the batteries at night and not use grid power?
    You do understand that this will be less cost effective?

    Every watt you take out of the battery bank will require putting 1.15 watts to refill. You can add another 10-15 % for the inverter losses as well.

    If I understand you correctly, this will be counterproductive, as in more expensive.
    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: 1,304 ✭✭✭✭
    Photowhit said:
    Masterjoe said:
    Anyone know how I would set my system to invert from the batteries at night and not use grid power?
    You do understand that this will be less cost effective?

    Every watt you take out of the battery bank will require putting 1.15 watts to refill. You can add another 10-15 % for the inverter losses as well.

    If I understand you correctly, this will be counterproductive, as in more expensive.

    Agreed, the 100% utility payback would make it impossible to actually save using the batteries, leaving them just for backup, sitting in float most of their life, the 100% can't be beaten, it really wouldn't matter how the batteries are charged, grid or solar, it's a status quo, the only way to come ahead is if there is peak billing periods and load shaving, but that has not been mentioned by @Masterjoe
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

Sign In or Register to comment.