Solar charge controller?

rcharrette

Adventurer
Hi all, for the past 2 years now I've been slowly building our solar system for our camper. I initially purchased a Renolgy 100W starter kit

(Renogy 100 Watts 12 Volts Monocrystalline Solar Starter Kit w/ 100W Solar Panel + 30A PWM Negative ground Charge Controller)

Next purchase another 100W panel and installed it on the roof, so I now have 200W on the roof.

Then finally I just installed a Victron BMV-712 battery monitor system.

Now I'm wondering if I should upgrade the charge controller to a MPPT? It seems that the MPPT is far superior to the PWM controller. More efficient and able to squeeze more power out of the panel to the battery.

My question is would it be worth upgrading to a MPPT controller?

If it is should I stick with a 30amp controller? Is there a reason to go bigger. My converter is 55amps.

The one I'm considering is a Victron SmartSolar MPPT 100/30https://www.amazon.com/Victron-SmartSolar-Charge-Controller-Bluetooth/dp/B073ZJ3L13/ref=sr_1_3_sspa?s=lawn-garden&ie=UTF8&qid=1548819079&sr=1-3-spons&keywords=victron+SmartSolar+MPPT+100%2F30&ps c=1&smid=AERMGYAT5R869

Finally, I have 2 - 6Volt batteries giving me 215 Amp/hrs
 

another_mike

Adventurer
Im curious to see what people here think of the Victron Smartsolar's also. Im considering the 100/50 for my project. Did a search and found a handful of posts and saw nothing bad.

I suppose a question which will come up from the more knowledgeable people are. Your Solar Panels, wired in series or parallel?
 

dwh

Tail-End Charlie
I have a 100/30 with a 300w 36v panel.

First of all, your converter has nothing to do with it.

With the Victron, 100/30 means it can handle an input voltage of up to 100v from the solar and output up to 30a to the battery. Those are the max limits.

The 55a rating of the converter means it can supply up to 55a output on the 12v side.

Victron makes a bloody good product at a decent price, plus you can add a bluetooth dongle so you can talk to it with their app.

But MPPT doesn't gain you all that much with solar less than 200w, so l probably wouldn't spend the money to replace a good PWM controller for only 200w of panels. I had to use MPPT because my panel is 36v.
 

rcharrette

Adventurer
@another_mike , well this is how "ignorant" I am with solar (but trying to learn!!). I have no idea if I'm series or parallel. I bought my fist Renolgy Panel as a solar kit with charge controller. I then bought a second 100Watt panel and it came with 2 connectors to simply tie the panels together.
https://www.amazon.com/gp/product/B00Q5W30FY/ref=ppx_yo_dt_b_asin_title_o01__o00_s00?ie=UTF8&psc=1

@dwh Thank you for the explanation. That makes sense. I'll probably hold off for now and see if I add any more panels in the future then revisit it.
 

dreadlocks

Well-known member
If you use PWM then you wire your panels up in parallel, if you use MPPT then you'd probably want to wire em up in a series, this will take advantage of higher voltages for less losses and better output.

Victron Chargers provide datalogging and a bunch of stats via bluetooth, which is really nice and IMO worth it alone.. MPPT is also nice, usually most of us want/need more solar than we have the room to carry, so squeezing out every drop of efficiency from what you can get to fit starts to become a rather worthwhile expenditure.
 

dwh

Tail-End Charlie
so squeezing out every drop of efficiency from what you can get to fit starts to become a rather worthwhile expenditure.

Most would be a lot better off tilting their panels rather than worrying about a few extra watts from MPPT.

But how many bother with that? Not many. So they flat mount the panel and then worry that they need MPPT to improve efficiency?

Meh.
 

dreadlocks

Well-known member
shrug, with non fixed panels I chased the sun with em all day and found it obnoxious.. but I needed alot more solar than I could carry at the time so I kept panels nice and clean and drug em around the forest seeking out direct sunlight.

I may be totally abnormal, but I accepted that decades ago.
 

Rando

Explorer
If you use PWM then you wire your panels up in parallel, if you use MPPT then you'd probably want to wire em up in a series, this will take advantage of higher voltages for less losses and better output.

Victron Chargers provide datalogging and a bunch of stats via bluetooth, which is really nice and IMO worth it alone.. MPPT is also nice, usually most of us want/need more solar than we have the room to carry, so squeezing out every drop of efficiency from what you can get to fit starts to become a rather worthwhile expenditure.

Agreed entirely. The Victron Smart Solar are worth it for the data interface alone, the MPPT is a bonus. Do you need one of these? No. But you don't actually NEED any of this junk, it is a hobby and watching your solar charge controller through the app adds to the fun.
 

another_mike

Adventurer
I have a 100/30 with a 300w 36v panel.
.
Curious, Do you have a link to your build? Im planning on also doing A Victron with a single 300 watt panel and the formula I found online showed I should account for possibly 32amps of output. Since youre well respected here, I dont doubt your system works, but If I can save $100 by getting the 100/30 over the 100/50 im all for it! I dont want to derail this thread with my build discussion.
 

dwh

Tail-End Charlie
Curious, Do you have a link to your build? Im planning on also doing A Victron with a single 300 watt panel and the formula I found online showed I should account for possibly 32amps of output. Since youre well respected here, I dont doubt your system works, but If I can save $100 by getting the 100/30 over the 100/50 im all for it! I dont want to derail this thread with my build discussion.

Hey, thread drift is what we do around here, no worries.

I don't have a build thread. I have a 1976 Ford camper van that I paid $200 for many years ago. It's a beater. I suppose I could try and pimp up its image and call it a "rat rod" camper van, but the truth is I just decided I would never put a dime into a $200 camper that I didn't absolutely have to...so I didnt.

I have another project, a 1972 Superior 2200 RV that I plan to restomod one of these days. Since the van is on its last legs, I will strip off the bits I want to keep and junk it. Eventually. Maybe this year. Maybe next. We'll see.

I ended up with a 300w panel and 400ah of AGM because a guy here on ExPo who was a documentary filmmaker built a van for camping in while shooting something or another in the desert. After like a year and hardly any use and the project was done, he stripped the stuff off the van and sold it. The charge controller was a 30a Midnite Kid and it sold fast. Months later, he still had the panel and batteries.

My nephew wanted to build a solar powered backup system for his home computer network (he's an IT guy that I trained in networking), so I pointed him at the ExPo guy who was local. Told my nephew how to check the stuff. It checked out, so he grabbed 2x 4D 200ah 12v AGMs (Chinese), and the 300w panel for $300 cash out the door.

Six months later, the stuff was in his garage, unused, and he took a job out of state and was going to be in an apartment, so he no longer needed the stuff. Tried to just give it to me, but I said no, and paid him the $300 he paid for it and did a quicky install on the camper van.

But I needed a charge controller. The 100/30 plus a meter was around $300, so I bought it. One reason was Victron is good stuff at a decent price. Another was I needed MPPT because the panel is 36 Vmp. Had it been 18 Vmp, I probably would have went with a 25a Morningstar SunSaver Duo PWM. Another plus was the Victron has several default charge profiles builtin (can be reprogrammed with the app if needed). One was the perfect 14.7v bulk, 14.7v absorb that my Chinese AGMs wanted.

The 40y.o. Norcold 323 fridge was acting up (pilot would go out at random unexpected times), so some mechanics at work (Penske Truck Leasing) kept an eye out and snagged me a 12v fridge from a lease turn-in and I put that in the camper.

Which is how I ended up with a $1,000 solar system and an $800 fridge - that I paid a total of $600 for - in a $200 camper. :D

(Well, okay...the fridge did come at a price...a few dozen Krispy Kremes for the shop crew. A bloody good investment, since they later snagged me another identical fridge, somewhat beatup but working, so now I have a spare.)

Had the solar about a year and half, but I was working (retired, but still like to work some), and it just basically sat around, keeping the batteries topped up and keeping the 12v TruckFridge cold.

I've had some time to fool around with it this winter (southern California). Took the battery bank down for a capacity test (tested out at 370ah @ 20hr rate), then let the solar do its thing. Did it a couple times.

The most I saw with the panel flat mounted and winter sun angle was maybe 180w, and that didn't happen until the battery got up over 12v and hit its lowest resistance.

I did note that the Astroenergy panel performed just as well, if not better, in hazy conditions, than it did with bright clean sun, which was a pleasant surprise. I chalk it up to a lower operating temp for want of a better explaination.

Theoretically, this panel could exceed 30a by a bit. But it's flat mounted, so that's a negative factor, and during summer it'll be hot, which is another neg. True, the 100/30 won't allow more than 30a to flow to the battery...even IF the solar could produce that (I doubt it ever will), AND the battery could absorb it (my 400ah bank could, at least for part of the bulk stage).

So really, a 30a charge controller is just about perfect for a 300w panel, and 90% of the time (or more), is never going to hit the limit anyway.


Eventually, I'll move the system over to the RV project. But the Superior has a battery compartment with a sliding shelf that can hold two batteries, period. It is just barely tall enough for a group 31 to fit. It's wired for both starting and house batteries to be in that compartment, and I don't really want to change that. At this point I'm thinking to just keep that setup, and add maybe 200w of panel (anyone else notice that Home Depot now sells Renogy?), plus a SunSaver Duo, and keep the lights and water pump on a single 100ah battery.

Then I can use the big panel and battery bank to feed a 12v fridge. The RV has a 7cu' Dometic ammonia fridge right now, so I'll either need one big one or a couple of smaller ones. Most likely a fridge with a door, and below that a drawer type freezer.

I'll probably add a big inverter/charger as well...not that I'd really need it, but just because.
 

jonyjoe101

Adventurer
With 200 watts of power the most you will get out of them with mppt is about 13 amps if you connect them in series and your battery is depleted and the sun is right overhead, normally if you get 10 amps that would be good. If you are getting less then 10 amps in your current system maybe mppt will be a good upgrade for you.

If you need an mppt, for your system I recommend the ecoworthy 20 amp mppt (100 dollars), it has lcd screen and all the voltage parameters can be programmed on the unit. I had mine for almost 6 years and used it with lead acid and now on lifepo4. I seen it go as high as 15 amps from my 240 watt panel when charging lithium.
The price on the victron 100/30 is 226 dollars, I dont like that it has no lcd screen and you need a smartphone to program it, those would be dealbreakers for me.

It never hurts to have 2 charge controllers always available just in case one goes bad. I have a small inexpensive 20 amp pwm that I can install right away. You never want to be without power.
 

dreadlocks

Well-known member
fwiw the victron 20A is $160, and 15A is under $140 and you dont have to use the app.. you can purchase an external panel mount display if you like and program it through that.. he already has a Victron BMV so they would match nicely and use the same app and could even share like battery temp with eachother.

however its better to buy once, if OP has any concerns about expanding solar further down the road its better to buy bigger than he needs now.. itd make going to 300W alot more expensive later if he builds with a 200W ceiling.. just keep that in mind, I've got a 10A MPPT controller on the shelf I outgrew.
 

Howard70

Adventurer
I'm not sure if this has been mentioned up thread or not (didn't find with a quick read) but the advantage provided with MPPT decreases with increasing temperature. In other words I see the greatest increase in amps to batteries versus amps from panels in the coldest temperatures. That's fine with us as cold winter conditions (low angle sun, often cloudy skies, short days) combined with greater use of stored energy (more furnace time, heating water, more interior lights, rare use of block heater,etc) combine such that we like every amp we can get.

When it is hot, the amps from panels and amps to batteries converge such that we don't notice a great difference. Another advantage of MPPT is the potential for high voltage panels which allow for smaller gauge wire between panels and controller. If you have a large truck or like to run portable panels from a shaded truck out to the sun, thinner wire is nice.

Howard
 

another_mike

Adventurer
Hey, thread drift is what we do around here, no worries.

I don't have a build thread. I have a 1976 Ford camper van that I paid $200 for many years ago. It's a beater. I suppose I could try and pimp up its image and call it a "rat rod" camper van, but the truth is I just decided I would never put a dime into a $200 camper that I didn't absolutely have to...so I didnt.

I have another project, a 1972 Superior 2200 RV that I plan to restomod one of these days. Since the van is on its last legs, I will strip off the bits I want to keep and junk it. Eventually. Maybe this year. Maybe next. We'll see.

I ended up with a 300w panel and 400ah of AGM because a guy here on ExPo who was a documentary filmmaker built a van for camping in while shooting something or another in the desert. After like a year and hardly any use and the project was done, he stripped the stuff off the van and sold it. The charge controller was a 30a Midnite Kid and it sold fast. Months later, he still had the panel and batteries.

My nephew wanted to build a solar powered backup system for his home computer network (he's an IT guy that I trained in networking), so I pointed him at the ExPo guy who was local. Told my nephew how to check the stuff. It checked out, so he grabbed 2x 4D 200ah 12v AGMs (Chinese), and the 300w panel for $300 cash out the door.

Six months later, the stuff was in his garage, unused, and he took a job out of state and was going to be in an apartment, so he no longer needed the stuff. Tried to just give it to me, but I said no, and paid him the $300 he paid for it and did a quicky install on the camper van.

But I needed a charge controller. The 100/30 plus a meter was around $300, so I bought it. One reason was Victron is good stuff at a decent price. Another was I needed MPPT because the panel is 36 Vmp. Had it been 18 Vmp, I probably would have went with a 25a Morningstar SunSaver Duo PWM. Another plus was the Victron has several default charge profiles builtin (can be reprogrammed with the app if needed). One was the perfect 14.7v bulk, 14.7v absorb that my Chinese AGMs wanted.

The 40y.o. Norcold 323 fridge was acting up (pilot would go out at random unexpected times), so some mechanics at work (Penske Truck Leasing) kept an eye out and snagged me a 12v fridge from a lease turn-in and I put that in the camper.

Which is how I ended up with a $1,000 solar system and an $800 fridge - that I paid a total of $600 for - in a $200 camper. :D

(Well, okay...the fridge did come at a price...a few dozen Krispy Kremes for the shop crew. A bloody good investment, since they later snagged me another identical fridge, somewhat beatup but working, so now I have a spare.)

Had the solar about a year and half, but I was working (retired, but still like to work some), and it just basically sat around, keeping the batteries topped up and keeping the 12v TruckFridge cold.

I've had some time to fool around with it this winter (southern California). Took the battery bank down for a capacity test (tested out at 370ah @ 20hr rate), then let the solar do its thing. Did it a couple times.

The most I saw with the panel flat mounted and winter sun angle was maybe 180w, and that didn't happen until the battery got up over 12v and hit its lowest resistance.

I did note that the Astroenergy panel performed just as well, if not better, in hazy conditions, than it did with bright clean sun, which was a pleasant surprise. I chalk it up to a lower operating temp for want of a better explaination.

Theoretically, this panel could exceed 30a by a bit. But it's flat mounted, so that's a negative factor, and during summer it'll be hot, which is another neg. True, the 100/30 won't allow more than 30a to flow to the battery...even IF the solar could produce that (I doubt it ever will), AND the battery could absorb it (my 400ah bank could, at least for part of the bulk stage).

So really, a 30a charge controller is just about perfect for a 300w panel, and 90% of the time (or more), is never going to hit the limit anyway.


Eventually, I'll move the system over to the RV project. But the Superior has a battery compartment with a sliding shelf that can hold two batteries, period. It is just barely tall enough for a group 31 to fit. It's wired for both starting and house batteries to be in that compartment, and I don't really want to change that. At this point I'm thinking to just keep that setup, and add maybe 200w of panel (anyone else notice that Home Depot now sells Renogy?), plus a SunSaver Duo, and keep the lights and water pump on a single 100ah battery.

Then I can use the big panel and battery bank to feed a 12v fridge. The RV has a 7cu' Dometic ammonia fridge right now, so I'll either need one big one or a couple of smaller ones. Most likely a fridge with a door, and below that a drawer type freezer.

I'll probably add a big inverter/charger as well...not that I'd really need it, but just because.
I only half the batteries you do.. two 31 series 105ah AGM's.... I was more worried about the solar panel matching the controller, but maybe I misunderstand something...

Lets say you have 100/30 MPPT and you have less than the 100v's going in, but a panel setup is still capable of producing say 40 amps of output (lets not pay any attention if the battery bank can receive this much or not at this point).... Would the 30amp output controller still work? just be limited to 30 amps of output? or would this cause a problem for the controller?
 

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