Here is a bit more on how RE-BULK and RE-FLOAT interact with the ABSORB timer. All battery voltages are default and are given as 12VDC nominal, multiply by 2 for 24V and 4 for 48V systems. All of the following is true for grid-tie GV or GT FXs only.
Definitions: BULK - Constant high current increasing battery voltage to reach absorption stage. Absorption (ABSORB) - Constant high battery voltage (target 14.4 volts), tapering current as battery capacity is filled. FX can charge or sell to this voltage target. FLOAT - Charging cycle is complete from absorption stage, constant low voltage (default 13.6 volts) trickle charge to maintain full battery. FX can charge or sell to this voltage target. SellRE - Charging cycle also completed, constant low voltage (target 13.0 volts) target similar to Float. Sell RE is typically set lower than float in order to minimize trickle charge to battery and force more renewable energy to be exported from the FX inverter. FX can only sell(not charge) to this voltage target. Equalize (EQ) - High voltage (target >15 volts) over charge of the batteries meant to bubble electrolyte which stirs it up to maintain equal concentration throughout the battery, and to create equal cell voltages throughout the complete battery string. FX can charge or sell to this voltage target. Pass thru - the FX is not converting any power and is silent All the stages above have target DC voltages associated with them. For instance, if the FX is in Float mode, the target voltage for the battery is 13.6 volts. While grid is available the FX can draw current from grid to maintain 13.6 volts. If a DC renewable energy source is supplying enough power to bring the batteries above the 13.6 volt target, the FX can send current to AC loads or back out the grid input to keep the battery at 13.6 volts. The FX is a bi-directional power conversion device that will do everything possible to maintain 13.6 volts. Without grid input, the FX will not be able to actively maintain the battery voltage at the current target, although the FX will still go through the same stages, keeping track of battery target and timers. If the DC sources are less then the AC load demands, the battery voltage will fall. This can trigger a REFLOAT or REBULK dependent on how low the battery voltage falls. Conversely, if the DC sources exceed the AC load demands, the FX cannot maintain the battery voltage at any specific target. Battery voltage will rise to what ever voltage the DC source controller allows. Typical FX charger behavior: On initial DC power up of all grid-tie FX inverters, a 1 hour stock absorption exists. Once AC power has been accepted by the FX, the BULK cycle begins. After the battery voltage reaches the Absorption set point, the absorption timer starts counting down and maintains absorption voltage for the absorption time. Watching the absorption time is the indication of how long the FX will be in the absorption mode. After the absorption mode is finished, the next stage is Sell RE. Sell RE is a target that the FX cannot charge too, but can export renewable energy if the source is powerful enough. Towards the end of the day, typical renewable energy, like solar, is not available so the FX cannot export any more power. In this event the FX will go silent/passthru, which means it stops any power conversion. The battery usually still has small DC loads, so battery voltage may slowly fall during the night. If the battery voltage falls below the RE-FLOAT setpoint (12.5 volts) then the FX will transition to the FLOAT stage and charge the battery to the FLOAT target (13.6 volts) for the FLOAT time (1 hour). After the FLOAT timer has expired, the FX returns to the SellRE stage and/or silent/passthru. If the battery falls past the REFLOAT setpoint, below 12.4 volts (which we call RE-BULK), the FX will change to the BULK stage and the absorption time remaining will start counting up. The absorption time remaining will count up in real time as long as the battery voltage is 12.4 volts or below. The absorption time remaining counts in double time if the battery voltage is less than 12.0 volts and counts in quadruple time if battery voltage is less than 11.6 volts. In other words the lower the battery voltage goes the more time the system will have to remain in the absorption stage up to the absorption time setpoint. When charging sources (grid or renewable energy) are available again then the FX can satisfy the absorption stage and continue on to the SellRE stage again. Although the stages may seem confusing, they are all dependent on battery voltage and what target the FX has. The status/meters 1st screen top line always tells you what the FX is doing and what the target is. The first word is what the FX is actually doing (PASSTHRU, CHARGE, SELL) and the second word is the target (BULK, FLOAT, SELLRE, and EQ) where the FX wants to be. Other sources/loads in you system can achieve these targets besides the FX. All timers for any particular stage can be satisfied by the target voltage being maintained for that stages time. The only stage that has no timers associated with it is SellRE. One more thing to keep in mind, charger modes (BULK, ABSORB, FLOAT) take precedence over SELLRE. Setting SELLRE at or below REFLOAT or REFLOAT at or below RE-BULK, will cause unusual system behavior. Steve Higgins. Sr Application Engineer. Sub-Saharan Africa Business Dev Mgr. Outback Power Systems. 19009 62nd Ave Ne Arlington Wa 98223 360-618-4313 From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Monday, April 05, 2010 8:34 AM To: RE-wrenches Subject: [RE-wrenches] Fwd: Outback Grid Problems Here's the latest comments from my customer on this. Seems to be just a problem under reduced array output. Thanks again for everybody's valuable input. R. Walters r...@solarray.com Solar Engineer Begin forwarded message: From: "Roger L. Johnson" <rogerjohn...@itltd.com> Date: April 5, 2010 9:02:03 AM MDT To: Ray Walters <r...@solarray.com> Cc: Andy O'Reilly <a...@positiveenergysolar.com> Subject: Re: [RE-wrenches] Outback Grid Problems Ray - I appreciate all the comments and recommendations relative to the grid voltage parameters. However, in my opinion, there is no data to support the contention that this is a source of the FX BULK CHARGING behavior. My reasons for coming to this conclusion are the following: 1. After a week and a half of careful monitoring, I have not seen any grid input/output voltage which varies from 123 +1 VAC. 2. No. 1 has been the case under all current conditions, ranging from heavy house load use to sell mode currents as high as 10 aac. 3. We have never seen a "STOP SELL" code which indicates over or under limit VAC. We have now had over a week of consecutive days of NO SNOW LOAD, that is to say, the arrays have been clear every morning. We start each morning with a battery voltage of 25.6 which, as the first sun falls on the arrays, quickly moves up to the FLOAT level and the new array CC's go into GT MODE and the systems starts selling. The system sells consistently depending on cloud cover and stops selling at the end of the day (sunset). The STOP SELL code at the end of the day is No. 8 or SAVE COMMAND (per the MATE manual). Yesterday (Sunday), we generated 31 kWH off the arrays and sold 5 kWH back to KCE over the 24 hour period. We had a fairly heavy "house load" yesterday since we pumped the deep well for about 2 hours. This morning, we started selling at 0815 hours and expect to be selling throughout the day. I took the time to go over my daily logs on the system since the "turn on" in December. The issue associated with the BULK CHARGING CYCLE seems to always have been associated with heavy snow load and the slow melt off during the following days. This takes us back to the question that OutBack seems to have trouble answering: What are the conditions (parameter values) that FX uses to kick the system into a day long BULK CHARGING CYCLE? During the times when I experienced this behavior, I saw STOP SELL CODES of 7,8, and 10. Again we have never seen code No. 3, VAC over voltage. If we knew this information, we might very well be able to understand the behavior. In summary, I do not think we have a system issue as much as I think we have a vendor issue (not willing to disclose needed info). I suggest that I continue to monitor the system on a daily basis and I will let you know if we experience anything interesting. I do think it is worthwhile for you to continue to obtain the information relative to the FX BULK CHARGING criteria from OutBack. RLJ on 4/4/10 10:53 PM, Ray Walters at r...@solarray.com <x-msg://341/r...@solarray.com> wrote: Here's something else that would be easy to try, and wouldn't hurt anything. R. Walters r...@solarray.com <x-msg://341/r...@solarray.com> Solar Engineer Begin forwarded message: From: "Steve Higgins" <shigg...@outbackpower.com <x-msg://341/shigg...@outbackpower.com> > Date: April 4, 2010 10:02:43 AM MDT To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org <x-msg://341/re-wrenches@lists.re-wrenches.org> > Subject: Re: [RE-wrenches] Outback Grid Problems Reply-To: RE-wrenches <re-wrenches@lists.re-wrenches.org <x-msg://341/re-wrenches@lists.re-wrenches.org> > Not that I'm aware of... We just use it as a quick fix for those customers with a less than perfect grid connection. Unfortunately with some grid connections even this doesn't fix the problem. It Open the voltage window from 108 to 132 and frequency to +/- 2 Hz. It would be nice to know what the disconnect, or stop sell reason is... it would give us a better understanding of what is going on. Steve Higgins. Sr Application Engineer. Sub-Saharan Africa Business Dev Mgr. Outback Power Systems. 19009 62nd Ave Ne Arlington Wa 98223 360-618-4313 -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org <x-msg://341/re-wrenches-boun...@lists.re-wrenches.org> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of penobscotso...@midmaine.com <x-msg://341/penobscotso...@midmaine.com> Sent: Sunday, April 04, 2010 8:26 AM To: RE-wrenches Subject: Re: [RE-wrenches] Outback Grid Problems That's a great tip Steve. Is there a downside to changing this setting? Daryl Ray, If you go to the Status FX Sell menu what is the disconnect reason when it does this? Also have you set the Grid Tie Authority from IEEE to User, when customers are all the way out at the end of the line sometimes the grid isn't as pretty and UL1741 and 1547 require so if the Grid Tie Authority is IEEE the inverter can disconnect prematurely. Changing this to User will open up the disconnect windows a bit so you don't disconnect prematurely. Steve Higgins. Sr Application Engineer. Sub-Saharan Africa Business Dev Mgr. Outback Power Systems. 19009 62nd Ave Ne Arlington Wa 98223 360-618-4313 -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org <x-msg://341/re-wrenches-boun...@lists.re-wrenches.org> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Tuesday, March 30, 2010 11:54 AM To: RE-wrenches Subject: Re: [RE-wrenches] Outback Grid Problems I considered that there could be something happening due to the grid, as this guy is way out on the end of the line going into his own utility transformer. But then the inverter should show a fault light, and it should try back again, once the grid voltage drops. Instead it initiates a full charge cycle and will not connect till the next day. R. Walters r...@solarray.com <x-msg://341/r...@solarray.com> Solar Engineer On Mar 30, 2010, at 10:57 AM, Brian Teitelbaum wrote: HI Ray, Have you checked the grid voltage to see if there is variation during the day which would be enough to kick the inverters out of connection? Brian Teitelbaum AEE Solar -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org <x-msg://341/re-wrenches-boun...@lists.re-wrenches.org> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Tuesday, March 30, 2010 9:43 AM To: RE-wrenches Subject: [RE-wrenches] Outback Grid Problems We currently have a Grid Tie system with a pair of Outback inverters that are regularly dropping out of sell mode, and letting the arrays spend all day charging the battery bank. It seems to do this several times a week, and the customer is losing substantial production, and gassing the batteries too much. It will reset itself the next day, or the customer resets it by turning off the inverters manually. The system is 24 v, with an old array of 1800 watts running through 2 FM60s, and a new array of 2800 watts running through another pair of FM60s. The battery bank is HUP about 4100 Ah @ 24 v (3 strings of 1375 Ah each) Big battery, I know, but the customer is an electrical engineer, who wanted maximum storage capacity. Outback tech support has not resolved the issue, and this has turned into several service calls, and customer frustration. We've tried running the controllers through the HUB, and also independently, and that doesn't make a difference. I have numerous Outback GT installs dating back to 2003, and have never had a problem like this. Any help or advice would as always be greatly appreciated. Thank you in advance fellow Wrenches, R. 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