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electrical:solar:status [2023/09/22 11:35]
frater_secessus [setups with no float] |
electrical:solar:status [2024/08/22 17:22] (current)
frater_secessus [then observe the controller] |
| [[lifestyle:words_of_wisdom|Words of wisdom]]: | [[lifestyle:words_of_wisdom|Words of wisdom]]: |
| > "Watching how many amps a charging battery is accepting at absorption voltage, is very indicative of state of charge, the less the amps the more charged." -- sternwake((https://vandwellerforum.com/showthread.php?tid=673&pid=11316#pid11316)) | |
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| >If you want to see lots more amps coming out of the [charge controller], put on a [significant] load... in the middle of a sunny day. -- John61CT((http://www.cheaprvliving.com/forums/Thread-Troubleshooting-solar-issues?pid=343191#pid343191)) | >If you want to see lots more amps coming out of the [charge controller], put on a [significant] load... in the middle of a sunny day. -- John61CT((http://www.cheaprvliving.com/forums/Thread-Troubleshooting-solar-issues?pid=343191#pid343191)) |
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| ====== Is my solar working? ====== | ====== Is my solar working? ====== |
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| | ===== TL:DR ===== |
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| | * if the **panel voltage** shown on the controller is ≤Vmp then the controller is making as much power as it can |
| | * if the panel voltage is >Vmp then the controller is restricting panel power on purpose |
| | * solar only makes power on demand; if the battery is charged and there are no loads then **no power will be produced**((where would it go?)) |
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| | [[opinion:frater_secessus:pareto|about these summaries]] |
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| | ===== overview ===== |
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| Note: for simplicity's sake this article assumes [[electrical:nominal|nominal]] 12v [[electrical:solar:panels|panels]] and 12v [[electrical:12v:intro|house power]]. | Note: for simplicity's sake this article assumes [[electrical:nominal|nominal]] 12v [[electrical:solar:panels|panels]] and 12v [[electrical:12v:intro|house power]]. |
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| It is common for those with new solar configurations to worry about whether or not they are working. The worry is understandable because: | It is common for those with new solar configurations to worry about whether or not the solar is working. This is understandable because: |
| - solar is $$$; and | - solar is $$$; and |
| - solar can seem magical; and | - solar can seem magical; and |
| This page is to help solar beginners tell what their system is doing without special equipment. A [[electrical:12v:battery_monitor|battery monitor]] can be extremely useful but we can tell a great deal without it. The info here is oriented to typical 12v systems with lead-acid battery banks. Folks running other battery chemistries or nominal voltages are assumed to already know what they're doing. :-) | This page is to help solar beginners tell what their system is doing without special equipment. A [[electrical:12v:battery_monitor|battery monitor]] can be extremely useful but we can tell a great deal without it. The info here is oriented to typical 12v systems with lead-acid battery banks. Folks running other battery chemistries or nominal voltages are assumed to already know what they're doing. :-) |
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| ===== numbers rather than icons or lights ===== | ===== common issues and non-issues ===== |
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| | In rough order from most common to least common |
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| | - NON-ISSUE: the battery bank is already charged |
| | - NON-ISSUE: the battery bank was charged in [[electrical:solar:status#setups_with_no_float|a no-float charging profile]] and is settling toward the rebulk setpoint |
| | - ISSUE: the panels are shaded((don't do that)) |
| | - ISSUE: there is a connection issue between the panels and controller (if it worked in the past) |
| | - ISSUE: the panels are incorrectly spec'ed for the controller or wired in a way to make it so (probably has never worked) |
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| | ===== the gory details ===== |
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| | ==== numbers rather than icons or lights ==== |
| Icons and blinking lights are often misleading or oversimplied. [[electrical:solar:tracer|Tracer/Renogy controllers]] are infamous for confusing battery graphics. Others like [[http://amzn.to/2yP01Ob|the Victron 75/15]] accurately show which charging stage is running. | Icons and blinking lights are often misleading or oversimplied. [[electrical:solar:tracer|Tracer/Renogy controllers]] are infamous for confusing battery graphics. Others like [[http://amzn.to/2yP01Ob|the Victron 75/15]] accurately show which charging stage is running. |
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| ===== first collect a few numbers ===== | ==== first collect a few numbers ==== |
| To tell at a glance what your system is doing you need to find a couple pieces of info about your system. You will only have to look them up once; it might be worthwhile to write them down on a sticky note near your solar gear. | To tell at a glance what your system is doing you need to find a couple pieces of info about your system. You will only have to look them up once; it might be worthwhile to write them down on a sticky note near your solar gear. |
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| {{ https://www.researchgate.net/profile/Kanaga-Gnana/publication/237049790/figure/fig3/AS:299465748566018@1448409606696/Characteristic-Curve-of-The-Solar-Panel.png?125}} | {{ https://www.researchgate.net/profile/Kanaga-Gnana/publication/237049790/figure/fig3/AS:299465748566018@1448409606696/Characteristic-Curve-of-The-Solar-Panel.png?125}} |
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| ==== panel specs ==== | === panel specs === |
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| The [[electrical:solar:panels#specifications|specs]] we are interested in are: | The [[electrical:solar:panels#specifications|specs]] we are interested in are: |
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| ==== controller ==== | === controller === |
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| ===== then observe the controller ===== | ==== then observe the controller ==== |
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| These checks are admittedly crude but will help see if your system is getting it done. No [[electrical:12v:battery_monitor|expensive or specialized equipment]] is required.((but use them if you have them!)) MPPT controllers in particular will reveal a great deal of information by how they interact with the panels. For the purposes of this article, consider [[electrical:solar:shunt_tweaking|single-stage/shunt controllers]] to work the same way as PWM except they only have one voltage setpoint.((Absorption OR Float)) | These checks are admittedly crude but will help see if your system is getting it done. No [[electrical:12v:battery_monitor|expensive or specialized equipment]] is required.((but use them if you have them!)) MPPT controllers in particular will reveal a great deal of information by how they interact with the panels. For the purposes of this article, consider [[electrical:solar:shunt_tweaking|single-stage/shunt controllers]] to work the same way as PWM except they only have one voltage setpoint.((Absorption OR Float)) |
| Vbatt - measured voltage of battery bank'' | Vbatt - measured voltage of battery bank'' |
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| ==== in bulk ==== | === in bulk === |
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| * charge delivered to battery holds steady((assuming sunlight holds steady)) Note: in a lab environment with DC power supplies the current (measured in Amps) could stay steady as the battery approaches Vabs.((the charger would get more and more wattage from the wall socket)) When charging off-grid we are typically limited by charging wattage, say 300w from the alternator or panels. At 12.1v you would see ~25A charging (300w/12.v = 24.79A) but at 14v you'd only see ~21.5A (300w/14v = 21.43A) | * charge delivered to battery holds steady((assuming sunlight holds steady)) Note: in a lab environment with DC power supplies the current (measured in Amps) could stay steady as the battery approaches Vabs.((the charger would get more and more wattage from the wall socket)) When charging off-grid we are typically limited by charging wattage, say 300w from the alternator or panels. At 12.1v you would see ~25A charging (300w/12.v = 24.79A) but at 14v you'd only see ~21.5A (300w/14v = 21.43A) |
| * **Example:** Panel voltage at Vmp == 17v, battery voltage 12.9v and rising, controller output steady-ish at 4A. | * **Example:** Panel voltage at Vmp == 17v, battery voltage 12.9v and rising, controller output steady-ish at 4A. |
| | * Note: while MPPT will ride Vmp during Bulk, Vmp will likely decrease somewhat as the day warms up and [[electrical:solar:output#panel_temperature|the cells derate]]. See the orange Vpanel line in [[https://img.mousetrap.net/2024/Screenshot_2024-02-15-17-04-01-028_com.victronenergy.victronconnect.jpg|this screenshot]]. |
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| **During bulk charging with PWM** | **During bulk charging with PWM** |
| * **Example:** Panel & battery 12.9v and rising, battery charging amps 2.5A and rising. | * **Example:** Panel & battery 12.9v and rising, battery charging amps 2.5A and rising. |
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| ==== in absorption ==== | === in absorption === |
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| * **Example:** Panel and battery voltage held at Vabs == 14.6v, controller output 2A and dropping | * **Example:** Panel and battery voltage held at Vabs == 14.6v, controller output 2A and dropping |
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| ==== transitioning to float ==== | === transitioning to float === |
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| When transitioning from Absorption to Float the voltage needs to drop about a volt. The system will "free-fall" (make little or no power) to allow the voltage to fall.((with MPPT controllers you may see Vpanel go quite close to Voc)) The transition may take seconds or minutes, depending battery chemistry and how/if the system is loaded. | When transitioning from Absorption to Float the voltage needs to drop about a volt. The system will "free-fall" (make little or no power) to allow the voltage to fall.((with MPPT controllers you may see Vpanel go quite close to Voc)) The transition may take seconds or minutes, depending battery chemistry and how/if the system is loaded. |
| * when Vbatt reaches Vfloat the system will start making power to hold //that// setpoint. | * when Vbatt reaches Vfloat the system will start making power to hold //that// setpoint. |
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| ==== setups with no float ==== | === setups with no float === |
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| Configurations with no float ("charge and stop", found on some Lithium profiles) will | Configurations with no float ("charge and stop", found on some Lithium profiles) will |
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| - charge to the Absorption ("boost") setpoint | - charge to the Absorption ("boost") setpoint((with or without some amount of Absorption duration)) |
| - **stop charging** | - **stop charging** |
| - until voltage falls to the rebulk ("reboost", "boost return voltage") setpoint, typically 13.2v | - until voltage falls to the rebulk ("reboost", "boost return voltage") setpoint |
| - repeat | - repeat |
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| The fall to reBulk looks like the transition to Vfloat described above. In both cases the controller makes no (or practically no) power until the lower setpoint is reached. | The fall to reBulk looks like the transition to Vfloat [[electrical:solar:status#transitioning_to_float|described above]]. In both cases the controller makes no (or practically no) power until the lower setpoint is reached. Lithium self-discharge is so minimal that unless a load is imposed it might not hit the rebulk setpoint and restart charging until the next morning. |
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| === Renogy confusion === | A constant cycling 14.4v->13.2v->14.4v might seem extreme but in practice there is little actual cycling occurring. A fully-charged 4S LFP with no loads will rest somewhere around **13.6v**. So for actual SoC changes we are talking about the difference between 13.6v and 13.2v. With significant loads applied 13.2v observed could mean SoC as high as 90% and with trivial loads as low as 70%.((with trivial loads there might be only 1 cycle a day since voltage would not fall to reBoost)) In normal use the real cycling might be 100%->85%-100% and the solar is helping carry the loads during charging periods. |
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| By default Renogy Li profiles work this way, and cause much concern for Renogy users who have not read their manuals and/or do not understand how solar charge controllers work. The required information is present [[https://www.renogy.com/support/downloads|in the manuals]] but Renogy should spell it out for the unfamiliar. | |
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| * Rover series - the table on page 37 of [[https://www.renogy.com/content/RNG-CTRL-RVR40/RVR203040-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile. The "boost return voltage" field shows **13.2v**. | == Renogy confusion == |
| * DC-DC/MPPT combo charger - the table on page 2 of [[https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile. The "boost return voltage" field shows **13.2v**. | |
| * DC-DC charger (20A/40A/60A) | By default Renogy Li profiles work this way, and cause much concern for Renogy users who have not read their manuals and/or who are not familiar with how solar charge controllers / chargers work. [The required information is present [[https://www.renogy.com/support/downloads|in the manuals]] but Renogy really should spell it out for first-timers. -- secessus] |
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| | * **Rover series** - the table on page 37 of [[https://www.renogy.com/content/RNG-CTRL-RVR40/RVR203040-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile. The "boost return voltage" field shows **13.2v**. |
| | * **DCC-series DC-DC/MPPT combo charger** - the table on page 2 of [[https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile. The "boost return voltage" field shows **13.2v**. |
| | * **RBC40D1S** - the table on p11 of [[https://store-fhnch.mybigcommerce.com/content/RBC40D1S-US/Renogy%2040a%20dcdc%20user%20manual%20v1.0%2020240320.pdf|the manual]] shows there is no float and it rebulks ("recharging") at 13.6v. |
| | * **DC-DC charger** (20A/40A/60A) |
| * page 18 says "lithium batteries will only have an absorption charge and no float charge" | * page 18 says "lithium batteries will only have an absorption charge and no float charge" |
| * there is no setting for Float charge, as shown in the table on page 17 of [[https://www.renogy.com/content/RNG-DCC1212-60-BC/DCC1212-204060-Manual.pdf|the manual]] and it says "for lithium... there will not be a float voltage" | * there is no setting for Float charge, as shown in the table on page 17 of [[https://www.renogy.com/content/RNG-DCC1212-60-BC/DCC1212-204060-Manual.pdf|the manual]] and it says "for lithium... there will not be a float voltage" |
| * the manual does not state the 13.2v boost return setpoint [an egregious error - secessus] | * the manual does not state the 13.2v boost return setpoint [an egregious error - secessus] |
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| If users do not like this behavior they can set up the USER profile to their liking, for devices that support it. | Users uncomfortable with this behavior can set up the USER profile to meet their needs, including defining [[electrical:12v:drop-in_lifepo4#mythyou_shouldn_t_float_lithium|a quasi-Float setpoint]].((low temp charging cutoff, when available, may only be available in canned Li profiles)) |
| ==== in float ==== | |
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| | === in float === |
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| **During Float with MPPT** | **During Float with MPPT** |
| * **Example:** Panel and battery voltage holding at Vfloat == 13.8v, controller output < 1A. | * **Example:** Panel and battery voltage holding at Vfloat == 13.8v, controller output < 1A. |
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| ==== when adding loads ==== | === when adding loads === |
| Adding a load can help reveal how much untapped power your system can access, and also prove that your system is working. | Adding a load can help reveal how much untapped power your system can access, and also prove that your system is working. |
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| ===== or use some traditional rules of thumb ===== | ==== or use some traditional rules of thumb ==== |
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| These are general targets to ensure the system is working at the bare minimum to meet your needs. They give a big picture but no information about what is happening at a particular moment. | These are general targets to ensure the system is working at the bare minimum to meet your needs. They give a big picture but no information about what is happening at a particular moment. |
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| ==== morning ==== | === morning === |
| **Are your batteries at a reasonable [[electrical:depth_of_discharge|state of charge]] in the morning?**((≥50% or ~12.1v for lead batts, ≥20% for Lithium)) If so, continue to Afternoon. | **Are your batteries at a reasonable [[electrical:depth_of_discharge|state of charge]] in the morning?**((≥50% or ~12.1v for lead batts, ≥20% for Lithium)) If so, continue to Afternoon. |
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| * [And stop running things off an inverter! -- secessus] | * [And stop running things off an inverter! -- secessus] |
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| ==== afternoon ==== | === afternoon === |
| **Are your batteries starting Absorption by noon-ish** and completing Absorption by late afternoon?((depending on charging voltage and current Lithium may require no absorption at all to reach 100% SoC)) If so, continue to the next step. | **Are your batteries starting Absorption by noon-ish** and completing Absorption by late afternoon?((depending on charging voltage and current Lithium may require no absorption at all to reach 100% SoC)) If so, continue to the next step. |
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| If not, [[electrical:solar:nonessential|delay running heavier loads]] until Absorption is underway. | If not, [[electrical:solar:nonessential|delay running heavier loads]] until Absorption is underway. |
| ==== evening ==== | |
| | === evening === |
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| **Are you hitting sundown with //at least// 12.6-12.7v((depending on your particular battery)) in your lead acid bank?**((~13.2v for LiFePO4)) If so, you can relax; your system is working well enough. | **Are you hitting sundown with //at least// 12.6-12.7v((depending on your particular battery)) in your lead acid bank?**((~13.2v for LiFePO4)) If so, you can relax; your system is working well enough. |
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| ===== sudden voltage spikes ===== | ==== sudden voltage spikes ==== |
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| If you are seeing sudden voltage spikes and have lithium batteries, you may be seeing [[opinion:frater_secessus:lifepo4_charging_voltage|the BMS disconnect the charging circuit]]. When this happens the controller suddenly finds itself making too much power (the charging demand suddenly disappeared); voltage on the rest of the circuit will spike while the controller reacts to the new demand level. | If you are seeing sudden voltage spikes and have lithium batteries, you may be seeing [[opinion:frater_secessus:lifepo4_charging_voltage|the BMS disconnect the charging circuit]]. When this happens the controller suddenly finds itself making too much power (the charging demand suddenly disappeared); voltage on the rest of the circuit will spike while the controller reacts to the new demand level. |
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| ===== MPPT tracking sweeps ===== | ==== MPPT tracking sweeps ==== |
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| {{ https://img.mousetrap.net/2023/Screenshot_20230208-095220.jpg?150}} | {{ https://img.mousetrap.net/2023/Screenshot_20230208-095220.jpg?150}} |
