I'm Greedy... Fastest Charge Controller? [ANSWER: Victron]

DougH

I have 300W in solar panels, 250Ah in AGM, a 2200W Giandel inverter, battery monitor, and 30A Epever Tracer MPPT charge controller with remote monitor.

It feels like my Epever is too cautious.  The MT50 remote display will show 20-40V, but the current being requested of the panels, or being allowed to flow, is based on the load, and what the Epever sees as the load on / state of the battery bank. 

So with only a fan or light on, the Epever and MT50 remote will show 20-40V based on sun direction, but hardly any current.  But under medium inverter load, when the battery monitor shows 60A being pulled out at 12.4V, the Epever is only sending 5-6A into the battery bank... or only 75W in perfect direct sun.  I want more.

The Epever does multiphase charging, and the overvoltage, boost voltage, float voltage, and a dozen other settings are appropriate for my bank... but there's no place in the control parameter settings where I can change the max current during bulk charge mode from 6A to 10-15A. I can only set voltage threshold values.  Since the inverter and solar controller hook up to the same battery lugs, if the inverter wants 50A and the solar could deliver 20A, I want the battery monitor to only show 30A net draw, if I'm saying all that in proper electrical terms.

It gets there eventually, and my batteries are doing well, but if I have 300W or more on the roof, I'd like to use more of the solar for air conditioning, rather than draw down the batteries and then recharge back up to 14.4V over the
course of hours once the A/C is off. 

It's like the Epever only monitors the battery voltage, not the current being asked of it, which makes sense, since as far as I know, nobody hooks a high power inverter to the load lugs of their converter.  So the Epever can't know the load accurately on the batteries.  It just knows the voltage has dropped from 14V to 12.5V because of some load, and it's not smart enough to assume there's a huge current going out so it should max out the solar going in.  Even Epever diagrams show the inverter should only be connected to the battery, not to the controller load connectors.  I'm guessing that even if I had 750W on the roof, it would only charge at 6A.  Maybe a mid-sized 250Ah bank is not supposed to be charged at 10-20A, but if there's 50A flowing out of those battery lugs, it's not like 20A going in would charge the batteries at all anyway... it would just flow from the panels to the inverter.  I guess I could cheat and tell the Epever I have a 1000Ah battery bank and see if it grabs more solar energy.

The Victron, Renogy, Epever MPPT controllers are all roughly the same price in this power range.  But for you folks with 200-400W of panels, do you have a controller that pulls more solar, or is smarter, or works with a battery monitor to bump up the solar draw appropriately?  Does a Victron battery monitor feed both the voltage and current and bank temperature to the Victron controller so it will grab every watt it can from the solar panels when called upon to do so? 

Cbusguy

Personal experience......victron is much faster than the renogy that it replaced.    The victron is able to replenish the shed battery bank by noon and finish absorption before I am home from work at 5pm.     The renogy would still be in bulk when I get home from work and would never exit abosorption and enter float

Nothing was changed in the system other than the charge controller. Yes the voltages are set the same for bulk absorption and float

What is interesting is the renogy reports higher current delivery than the victron,. No idea other than the reviews say that the victron switches power points quicker.   No idea

Keep in mind with lead acid you need to be concerned about max charge current.   Refer to your manufacturer s recommendation.     I know that when I select agm the default max charge current is 20 amps in the victron.   

Life4 can take 1c or 100 amps charge current.   That is at the expense of longevity

I did add the victron temp sensor for the battery.  It serves two purposes, it reports battery temperature and the real time battery voltages with no cable loss.   My understanding is with out the external sensor the solar controler only measures temp once a day.   Far as the voltage difference I have noticed it under very heavy loads.

I did network the two together within the victron app

DougH

@Cbusguy : Thanks, that's what I wanted to hear.  The Vmax battery spec says 8-35A.  Sounds like a Victron SmartSolar 100/20 or equivalent is in my future.

Cbusguy

I wouldn't charge it beyond 80 percent of max rates shortens the life......of course you are talking what.....28 amps.    

That is a bunch of current.

DougH

300W max will get close to that, but I'd be happy if an alternate controller approached 20A.  Thanks again.

pthomas745

So, after all this...you get to full charge 15 minutes faster?  What are the real world implications here?

Cbusguy

Better charging under less than optimal conditions and it will save more than 15 minutes

pthomas745

How much more? 

jkjenn

I think your boost could be limited by your solar setup, too. 300w can be either 1 panel or multiple panels. MPPT panels do a really nice job with higher voltages. So, if you are running a single 300w panel at a lower voltage capability than 3, 100w panels in series with greater voltage capability.

So, for example, if you are running a singular Renogy 300w 24v panel, you are maxing out at 24v. If you are running 3 ,12v panels in series at 12v, totalling 36v with a controller capable of 36v, you can get a little higher voltage. .

My Victron Blue Solar was a 48v and I think it was a little more efficient than my Victron Smart Solar. I was only using 24v but wanted it to be expandable, at the time. 

DougH

If it helps, it's three BougeRV ETFE 12V/18V panels in series.  I'd frequently get 36V with just two panels on a clear day, and recently added a third panel.  I'm hoping not just for faster recharge before float, but primarily less juice taken out of the batteries when the panels could provide more.  Thinking of the Victron 100/20 if I can find a non BT model with a physical monitor with decent UX/UI. 

rfuss928

IMO - A controller change will not make any significant difference.  The reality is PV panels output is rated under ideal conditions very rarely experienced.  With few exceptions you will seldom see more than 50% of a panels rated wattage.  Temperature, humidity and angle of incidence are all significant factors reducing a panels performance.  A perfectly aligned panel on a clear winter day at noon in Denver could come close to achieving rated output.  A curved roof mounted panel on your T@B in the sun in the northeast will produce much less.

I would have expected more than 75 watts from a 300 watt system under the conditions described but other possible influencing factors are unknown.  A different controller could possibly make a 1-2% difference but in this case it seems the power just isn't available.

In 7 years with 136 watts of PV panels on my T@B I have rarely seen more than 60 or 70 watts output.

BrianZ

I'm curious how your panels are wired - in series or parallel, and whether it could/would make a difference to your controller.  We've only got one panel, so I've never really been forced to think much about that, other that the fact that series wiring would result in lower current & less power loss in the transmission line.  

Our trojan battery guide shows this graph of the charging profile where max bulk current should be at least 10-13% of C-20..

For our 150AH battery, I assume that would mean charging at around 15 Amps.  We've only seen around 7 amps max with our Victron 75/15 SCC, but then our state of charge was typically never below about 80% on our Victron 712 monitor during our limited boondocking experience, nor did we ever have anything even close to your high power consumption.

rfuss928

jkjenn said:

So, for example, if you are running a singular Renogy 300w 24v panel, you are maxing out at 24v. If you are running 3 ,12v panels in series at 12v, totalling 36v with a controller capable of 36v, you can get a little higher voltage. .

 The output voltage of a charge controller is determined by its microprocessor and it is independent of the input V from the panels as long as the input exceeds the desired output V.  The greater the difference between input V and output V the more work the DC to DC converter has to do (assuming MPPT)and efficiency suffers.  The big advantage to series connection of the panels is the lower wiring losses resulting from the lower current for a given wattage.  If the controller is working properly, higher input V will not result in "a little higher voltage" output.

jkjenn

rfuss928 said:

jkjenn said:

So, for example, if you are running a singular Renogy 300w 24v panel, you are maxing out at 24v. If you are running 3 ,12v panels in series at 12v, totalling 36v with a controller capable of 36v, you can get a little higher voltage. .

 The output voltage of a charge controller is determined by its microprocessor and it is independent of the input V from the panels as long as the input exceeds the desired output V.  The greater the difference between input V and output V the more work the DC to DC converter has to do (assuming MPPT)and efficiency suffers.  The only advantage to series connection of the panels is the lower wiring losses resulting from the lower current for a given wattage.  If the controller is working properly, higher input V will not result in "a little higher voltage" output.

Sort of difficult to debate a generalization. But I definitely returned to full capacity running my panels in series than I did in parallel. I think the degradation of efficiency, in my own experience, is outweighed by higher performance, in real life.

rfuss928

jkjenn said:

Sort of difficult to debate a generalization. But I definitely returned to full capacity running my panels in series than I did in parallel. I think the degradation of efficiency, in my own experience, is outweighed by higher performance, in real life.

I agree, you likely got little higher power.  Significant power losses can be avoided by reducing wiring current to 1/2 or 1/3 of that in the same panels used in parallel.  Quite possibly the biggest advantage of MPPT controllers with high input V limits.  In comparison, the controller (DC to DC) efficiency differences are very small.  I would definitely run series with remotely placed arrays.

In the case of a system not keeping up with expectations, a controller change is very unlikely to make a significant difference in the systems capability.

DougH

Yup I'm in series, and I like these panels so far.  When I got the first two, I tested each stand-alone before VHB-ing them in place with a different PWM controller.  The voltage starts to come up before the sun does with these things, above 12V even without direct sun, and the PWM showed 15V or more once the sun hit them, and 4-6A for each panel.  That's what made me buy them.  Several reviewers said they were more resistant to hail than average, and were the first panels they had bought that matched spec. Radically better than first pair I had on the T@B.  The newest one I just put on is just a matte flat surface, not covered in tiny 1mm lenses, so I don't know if it will be as good with indirect sun.

https://www.amazon.com/dp/B07C94TPLT

I'm broke again, but will report back once I can afford the Victron 100/20.  I'm hopeful, and that's usually all that's required.

Didn't see a physical remote panel for the 100/20 where I can just glance and see PV amps and voltage, with same for battery.  Only the Bluetooth where you have to find phone, pair up, and scroll through screens.  Victron has something with all four numbers on a wired display, but just for the bigger models.  Bummer.

rfuss928

DougH

I agree,  maybe "old tech" but here is Battery Amps, Solar Amps, and Battery Voltage at a glance!

It even helps me remember which day of the week it is.........

Have fun!

jkjenn

DougH said:

Yup I'm in series, and I like these panels so far.  When I got the first two, I tested each stand-alone before VHB-ing them in place with a different PWM controller.  The voltage starts to come up before the sun does with these things, above 12V even without direct sun, and the PWM showed 15V or more once the sun hit them, and 4-6A for each panel.  That's what made me buy them.  Several reviewers said they were more resistant to hail than average, and were the first panels they had bought that matched spec. Radically better than first pair I had on the T@B.  The newest one I just put on is just a matte flat surface, not covered in tiny 1mm lenses, so I don't know if it will be as good with indirect sun.

https://www.amazon.com/dp/B07C94TPLT

I'm broke again, but will report back once I can afford the Victron 100/20.  I'm hopeful, and that's usually all that's required.

Didn't see a physical remote panel for the 100/20 where I can just glance and see PV amps and voltage, with same for battery.  Only the Bluetooth where you have to find phone, pair up, and scroll through screens.  Victron has something with all four numbers on a wired display, but just for the bigger models.  Bummer.

You can get an MPPT monitor for your older Victon solar controller and use a cable to connect them. 

DougH

@jkjenn : OK thanks, I'll try to find the non blue / non smart model at my power level, if still being sold, and go that way. 

DougH

@rfuss928 : I was looking on Amazon at the remote display for a Victron controller that would show PV amps, voltage, etc. with a glance.  You mentioned "old tech".  Tell me I'm wrong, but is that a 1980s DB9 connector on the back of the SmartSolar display unit?!?!

jkjenn

DougH said:

@rfuss928 : I was looking on Amazon at the remote display for a Victron controller that would show PV amps, voltage, etc. with a glance.  You mentioned "old tech".  Tell me I'm wrong, but is that a 1980s DB9 connector on the back of the SmartSolar display unit?!?!

I believe that there are a few models this works with but not all.

Cbusguy

Db9s are still an industry standard.    I connect to various hardware at work using them.  Secure and quick for a terminal link to see what's up with a device.


Much more secure than Bluetooth,.  Have you changed your default victron or renogy  Bluetooth access code?   

DougH

Won't buy the 100/20 until September.  Tiny pension, so I have to space out purchases. But is that a thing at campgrounds?  Go around changing settings on default coded Victrons as a prank?  Might be funny if a friend did it, but not so much if done by some bored random kid in the park.

DougH

@jkjenn ; @rfuss928 ; @Cbusguy :  Well finally bought and installed the Victron 100/20 controller this morning.  50% more juice already!!  Woo-hoo!!! 

THANKS, you folks were right, the Victron does charge faster.  With the sun hitting the panels at 60-70 degrees off-normal late this morning (back of trailer facing West), I was already seeing 9A going to the battery bank. This was while I was pulling 60A with the inverter. The best I ever saw with the Epever 30A controller (which is three times the physical size of the Victron) was 6A in almost perfect sun on 300W of fairly new ETFE flex panels.  The Victron is currently set to a max of 20A with the default AGM spiral setting on the bluetooth app so far (I'll have to look up the suggested voltage thresholds for the VMax Solar Tank batteries), but even at 9A it is already worth the $150 to switch over to Victron.

Thanks Again!



P.S.  I have two of the BougeRV version 2.0 panels that show up to 20V, and my oldest one is one of the original kind that only shows 15V (tested all three this morning), so since I'm running these in series (to charge early in the morning and late in the evening), I guess I should really replace that oldest one next month so they're all the same kind and voltage. 

Cbusguy

Glad it worked out and your findings are very similar to what I experienced upgrading solar controller.    I am interested to hear what your daily average turns out to be and how quickly you are able to replenish you batterys.

jkjenn

Great to hear!

Newbomb_Turk

Does anyone know if it’s possible to connect cables THICKER than the AWG 10’s listed in the Victron 75/15 Users Manual?  Say, AWG 8?

I’m a little obsessive (okay, a LOT obsessive) about voltage drop, and I want to connect the thickest possible cables between panels / controller and controller / batteries.

If there are any 75/15 owners out there that have tried using thicker cables (successfully or otherwise), your experienced counsel would be appreciated.

Cbusguy

You mentioned voltage drop.....do you have a nucamp installed system or a number of ground mounted panels.

Is the voltage loss in the wiring an issue?   If so how did you arrive at that conclusion?

Looking for additional info before posting my thoughts

Newbomb_Turk

@Cbusguy, I’m considering a do-it-youself system.  So far, the only things I’ve installed are two Trojan T-105’s and a Victron BMV-712 monitor.  (I’ll field verify our daily usage using the 712 before purchasing a controller and panels.)  

That said, I strongly suspect that I’ll go with the 75/15 Smart controller and a monocrystalline suitcase panel kit. (Panel size, rating, and brand TBD.) Victron seems to be controller the brand of choice, and I definitely want to go MPPT due to greater efficiency.

My voltage drop obsession comes from basic electrical engineering and my gut-level cost analysis. The additional cost of thicker cable is a one time, minimal factor, and if I can squeeze only 5% additional charging efficiency by using #8 cable, I’d consider it money well spent.  As you might guess, I’m trying to minimize cable length as well.

All I’m really trying to figure out is whether or not the cable ports on the Victron 75/15 are big enough to accommodate #8 cable.  

Sharon_is_SAM

It does say Max AWG 10.  How long of cables are you planning?  If it were me, I would put the extra coin into a more pliable marine wire extension.  Our 30 feet of 10 gauge wire is stiff and a challenge to store.

Newbomb_Turk

Sharon_is_SAM said:

It does say Max AWG 10.

Ah.  There you go.

Thanks, @Sharon_is_SAM!

(I’ll look at the marine wire extension.)