Newbie solar controller question

[FlyingScot]

We have 4 x 360wp panels. Each wired independently to their own Victron Smart 100/30.

The 100/30's are roughly $225 USD each. $900 total for 4.
The 150/100 is roughly $785. If you keep a spare now you have over $1500 in controllers. But you do get a display on the controller, but for me, ours are tucked away out of sight. The bluetooth app is easy to use. Since we keep multiple iOS devices on board, we can display the BMV and all 4 solar controllers at once if we want to. But it only take 3-5 seconds to swap between to any of the them using the app. Victron recently added 'trends' to the app which is also nice.

We don't keep a spare because we can easily live on 75% power.

We also have a BMV-712. The $25 optional battery temperature sensor is highly recommended. Otherwise the SC only look at temperature in the morning. Bluetooth network shares voltage and temperature to all 4 controllers.

We have an older iPad Mini that we use as our primary display. Normally showing BMV data.

Bottom line, if you have large panels that output high voltage, it makes sense to run one SC per panel.

Don't skimp on these items or you will be wishing that you took the time to buy highly efficient panels, controllers, wiring, etc.

[Paparuski]

Great question! Thanks for posting.

First, series vs parallel should not be part of the answer. The different in configuring these differ depends if you need more volts (e.g. 24 vs 12) OR if you need more AMPS.

Second, if all your modules (panels) are on the same plane (facing same direction) one solar charge controller will be fine. Get a good one that has MPPT ability in case of shading, etc. maximizes the energy collection.

If the modules (panels) are facing opposite direction, my understanding is that you will need separate charge controllers UNLESS someone knows of a special one that can handle this - it is my understanding most can not.

We all learn together!

[john61ct]

Originally Posted by moseriw

Sayin: "Oh thats no problem it'll work" is certainly not enough.

But in practice that is exactly the case.

There are enough real problems, this one does not need solving

[nilespf]

Not sure of the vintage of your panels but make sure they have bypass diodes.



Bypass diodes perform the function of bypassing current around a shaded PV cell(s). All the PV cells are wired in series. Any cell(s) that begin to impede and or reduce current output (typically due to shading) will begin to function as a passive device and as such will drop voltage across input to output. The value of the passive resistance will depend upon the amount of shading. Remember they are all wired in series. If for example the last cell in a panel fails OR you put your thumb across it and block sunlight the following happens. Let's say it is a 30V panel with 50 PV cells and it has been fabricated with 6 bypass diodes. Also lets say each PV produces .6 V volt so there is your 30V, At the input of the last PV the voltage level is 29.4V and at the output it is zero (because it has failed or you are shading it). Because the last PV is now (for all intents and purpose a passive circuit element) in a string of 50/6=5 diodes the output voltage drops to 30V-(.6 *5)-voltage drop of the bypass diode (typically .7V)= 26.3V. The bypass diodes function to bypass their respective string of 5 series PV's as needed.



Use the above and evaluate your particular installation variables. If your panels need to be wired in series because the Voc is not high enough (under shaded conditions) to support a decent voltage to charge your style of batteries then make sure you have a buck/boost controller. These are atypical in the less expensive realm of controllers.



Phil

[CatNewBee]

Originally Posted by moseriw

With 2 or more controllers you will face another problem. see the Victron DUO (btw. assistance from Victron does not exist. I believe Sterling is far better).

You have 2 Banks: 1 Automotive and one house so you connect The Stbd/Port DUO's to each bank.

DUO 1 decides to stop chargin completely to measure out if the battery is fully charged or not.

DUO 2 reckons that the battery has to be charged an rises to14,8V
and so on....


Technically I do not see a way to avoid the DUO's confusion and then, of course, malfunction.

And, of course, there is no believable statement from VICTRON.

Sayin: "Oh thats no problem it'll work" is certainly not enough.

It will work, don't worry, it's not rocket science...

[nilespf]

Originally Posted by CatNewBee

It will work, don't worry, it's not rocket science...

Actually unless the controllers do communicate with each other the feedback received by each is a effected by the voltage and current sensed by its respective bridge. When (and believe me they will) get out of sync with each other one will want to be in float and the other may have reached a conditioning phase. That is not necessarily bad only because the controllers do not/will not actively load the system (become a sink). But what it may do is affect the accuracy of the resulting comparison of battery energy (reported by the battery monitors) vs the charge controllers.



If both controllers are matched closely, load hogging will be minimized. If one seems to be always providing a bit more current than the other, it may not be due to performance of the respective panels.


Phil

[john61ct]

Charge sources are to be ignored for SoC information, once a proper BM is working.

And even the latter is rarely that accurate either, but at least keep you efforts resetting, calibrating etc to the BM.

[CatNewBee]

Originally Posted by nilespf

Actually unless the controllers do communicate with each other the feedback received by each is a effected by the voltage and current sensed by its respective bridge. When (and believe me they will) get out of sync with each other one will want to be in float and the other may have reached a conditioning phase. That is not necessarily bad only because the controllers do not/will not actively load the system (become a sink). But what it may do is affect the accuracy of the resulting comparison of battery energy (reported by the battery monitors) vs the charge controllers.



If both controllers are matched closely, load hogging will be minimized. If one seems to be always providing a bit more current than the other, it may not be due to performance of the respective panels.


Phil

It really does not matter, if one controller goes to float while the other keeps bulk or absorption program for a while, no need for synching or networking, they are networked at the battery terminals any way, they just make different decisions to what they measure.

In absorbtion there is a Amp drop any way, so it is sufficient if only one controller keeps charging, otherwise both or all controllers would have to turn down the output and may stop even charging because of low trailing Amp's. If some quitt earlier, the last controller has the real figures what the battery is acc epting and can properly end the absorption cycle.

You think too complicated, there is really no need to synch them, they elect the looser themselves who has to do the work while the rest is partying at float...

[nilespf]

Originally Posted by CatNewBee

It really does not matter, if one controller goes to float while the other keeps bulk or absorption program for a while, no need for synching or networking, they are networked at the battery terminals any way, they just make different decisions to what they measure.

In absorbtion there is a Amp drop any way, so it is sufficient if only one controller keeps charging, otherwise both or all controllers would have to turn down the output and may stop even charging because of low trailing Amp's. If some quitt earlier, the last controller has the real figures what the battery is acc epting and can properly end the absorption cycle.

You think too complicated, there is really no need to synch them, they elect the looser themselves who has to do the work while the rest is partying at float...

Everything was fine untill ..."You think too complicated" as a designer I can assure you that is something you don't hear or say in Preliminary through Final design reviews.


It was critical thinking that dictated system level specifications which allow these chargers to play nicely without needing to be networked AND allow you and I to chat about the subject at hand.



Some chargers may have certain parameters needing special consideration:


a ) Over Voltage Disconnect Voltage > Charging Limit Voltage ≥ Equalize Charging Voltage ≥ Boost Charging Voltage ≥ Float Charging Voltage > Boost Reconnect Charging Voltage.
b ) Over Voltage Disconnect Voltage > Over Voltage Reconnect Voltage
c) Low Voltage Reconnect Voltage > Low Voltage Disconnect Voltage ≥ Discharging Limit Voltage.
d ) Under Voltage Warning Reconnect Voltage > Under Voltage Warning Voltage ≥ Discharging Limit Voltage.
e ) Boost Reconnect Charging voltage > Low Voltage Disconnect Voltage.


I had to think about these settings the moment I chose to use two chargers and move away from default settings. If they are not setup correctly, trust me one charger can trip the other. It was my fault some parameters were too closely set and there is a small but measurable difference between voltages measured by the controllers. Now they do play nicely together.



Moseriw has a valid point in this thread.


Phil

[noelex 77]

Normally multiple charge sources do not present any problems.

Often one charge source will provide the majority of power in some circumstances. This upsets many users, but providing the battery is being fed with the right voltage at the right time, it is not detrimental if one charger source predominates.

There can be some conflicts that create minor issues. Often the absorption time is extended when multiple charge sources are used, potentially slightly overcharging the batteries.

There are also some specific issues for particular chargers. The popular Victron solar controllers have a tail amp termination of the absorption phase. There is no way to turn off this “feature” and it can, on occasion cause some issues.

[CatNewBee]

Originally Posted by noelex 77

Normally multiple charge sources do not present any problems.

Often one charge source will provide the majority of power in some circumstances. This upsets many users, but providing the battery is being fed with the right voltage at the right time, it is not detrimental if one charger source predominates.

There can be some conflicts that create minor issues. Often the absorption time is extended when multiple charge sources are used, potentially slightly overcharging the batteries.

There are also some specific issues for particular chargers. The popular Victron solar controllers have a tail amp termination of the absorption phase. There is no way to turn off this “feature” and it can, on occasion cause some issues.

Not really, except the cycle is shortened when two or more chargers charge almost in sync, so all of them notice low trailing Amp's and think the battery is full, while accepting 2 or more times higher Amp's,.

Stil academic and over complicated for the fanatics of exactly 100% SOC, and this is why:

* trailing Amp's as cut off parameter makes only sense in ideal setups, where there is only a charger and a battery with known capacity, chemistry, geometry of plates, temperature.

* in real world there are permanent, temporary, varying loads always connected to the battery as fridges, freezer, navigation instruments, autopilot, vhf, ssb radio, you name it. There is no ideal charge curve because the current and the resulting voltage at the battery varies independently of the charge sources all the time.

* there is no way to hit the point exactly, neither by voltage (voltage drops etc.) nor by current measurements at the controllers, not even at the battery shunt.

The controllers make a best guess, keep the voltage up for a while at absorption and then go to float. There the voltage is usually too high to discharge the battery but low enough to prevent high charging currents resulting in gasing and boiling to prevent SMF batteries from drying out the electrolyte. At float the charge sources may even pump significant Amp's into the system, directly consumed by the loads. If the loads exceed the sources Amp's, the voltage drops further and the battery contributes electricity to the system, eventually trickling another bulk phase.

The controllers set to the right chemistry take care of a good enough charge, even if some stop absorption charging earlier, because they would charge the remaining Amp's in float slower if alone, with multiple controllers, assuming all are set up and working properly, the battery will be charged properly to the specs, no matter if they are synced by communication protocols or not. They make the right decision and they revise it if something in the system changes, like voltage drop because of loads or increased voltage because of other charge sources like an alternator or another controller.

[noelex 77]

Originally Posted by CatNewBee

|
* trailing Amp's as cut off parameter makes only sense in ideal setups, where there is only a charger and a battery with known capacity, chemistry, geometry of plates, temperature.

A tailing amp cut off feature does not have any function on a marine system apart from rare instances (mainly if the boat is unsed with no draw).

It will only work with a single charge source and no load. This combination is rare on a boat. Unfortunately, the feature can cause minor and in some cases more severe disruption to the correct charging sequence. Tweaking the charge settings can diminish the disruption, but not eliminate the problem completely. Fortunately only a few charge sources incorporate the tail amp cut off feature, but it is present on the popular Victron solar controllers and there is no option to disable this feature, as there is in some other devices.

An example is a boat with a Victron solar controller and an alternator. This is only a simple system with only two charge sources. The tail amp cut off on the solar controller can still end the absorption phase much too early in some instances:

For example, early in the morning the solar controller will correctly be in the bulk, or absorption phase. If the engine is briefly started perhaps to motor out of the anchorage and the voltage setting on the alternator is slightly higher than the solar controller, the alternator output will cause the solar controller to drop to float if it is unfortunately equipped with the tail amp cut off feature. This is fine while the alternator is supplying enough power to charge the batteries correctly, but if the engine run is short, when the engine is stopped this charge source is lost. The solar controller will generally incorrectly stay in float mode even if the batteries are a long way from fully charged.

You may think setting both controllers to the same absorption voltage would solve this problem. Unfortunately it does not. Slight voltage calibration and voltage drop differences between the two different charge sources mean the voltages set points on the alternator and solar controller will not be the same even if they set to same numerical value.

The solution in the above example is to set the absorption voltage of solar controller just slightly above the alternator setting. This is an example of a simple tweak to help remove these conflicts.

Originally Posted by CatNewBee

The controllers set to the right chemistry take care of a good enough charge, even if some stop absorption charging earlier, because they would charge the remaining Amp's in float slower if alone, with multiple controllers, assuming all are set up and working properly, the battery will be charged properly to the specs, no matter if they are synced by communication protocols or not.

I don’t share this optimism. Many, perhaps even most, marine charging systems do not do a good job of caring for the batteries correctly. It has been said by others that most house battery banks don’t die, they are murdered .

Generally this is primarily the fault of the user, but the particular charge algorithm adopted by the manufacturer can make life difficult. Incorporating a trailing amps option that cannot be turned off is one example.

This is particularly a problem for solar regulators, as the same controller may be used by boats, RVs, home solar systems etc, so the algorithm is designed to work in a wide range of installations rather than a product that can be optimised for the conditions seen in a marine installation.

If you adjust your charge parameters to those recommended by the battery manufacturer you are doing much better than most, and deserve a passing grade, but there are significant and practical steps that can be taken to improve the system further. The tweak I have described above is just one example that can make a practical difference to battery life.

[CatNewBee]

Most batteries are murdered by too deep discharge, too frequent equalization and resulting loss of electrolyte or by poor maintenance not topping off distilled water frequently or over charging in storage when the yacht is not used, rarely by missing the 100% full charge and resulting sulphation, sometimes simply by choosing cheap starter batteries as house banks. The plates simply dissolve and brake, cause shortcuts and in massive parallel installations without proper fuses they destroy the other packs.

The permanent motions on rough seas also contribute to physical failures of wet batteries, not so much on spiral cell AGM, but they have other issues...

[FlyingScot]

We have 4 Victron 100/30s. It is my understanding the trailing amps feature was removed more than a year ago.
My Absorption voltage is set lower than it actually achieves. I do this to prevent overshoot above 14.4 or so.

I don’t think all 4 controllers need to be synched as in all be in the same mode at the same time. When our bank gets over approximately 92% it’s typical that one or two of the panels will drop to float. The other two will supply the needed power to cover house loads and finish charging the bank.

[nilespf]

Quote:
Originally Posted by CatNewBee
|
* trailing Amp's as cut off parameter makes only sense in ideal setups, where there is only a charger and a battery with known capacity, chemistry, geometry of plates, temperature.




My guess is the most widely used method (to gage transition to float) used by the recreational boating/RV industry. It is a logical and cheap method embraced by charging manufacturers (because of system level requirements) and endorsed by the battery manufacturers.



My boats house charger can keep the BM showing 100% only if the battery starts out at 100% and the only load is the 5A reefer. This occurs because the charger can adequately/accurately resolve the 5A load and has been designed/allowed to charge with a greater than 5A output during float mode.



My solar chargers usually do not do as well. They, (under the same conditions above) definitely can resolve changes in load currents but don't seem to always net out the system current draw from the battery to zero or slightly positive. As a result the battery is subjected to a very slow/shallow discharge rate.


Quote:
Originally Posted by CatNewBee
The controllers set to the right chemistry..................the battery will be charged properly to the specs, no matter if they are synced by communication protocols or not.


My guess is if the manufacturers ever realize the market is large enough to support the addional cost of hardware utilizing active feedback from BM's and purpose shunts (used to support truly smart charging) we will begin to see a blitz crieg of marketing articles questioning your contention.



I do believe using the dumbed down chargers we have to work with, an acceptable (not necessary optimum) charge system is easly created.


Phil