Should I go for a larger MPPT to get more amps back into the battery?

[Johnny Nova]

Hi
I'm planning a small campervan setup using a 200Ah battery powered by just one 200W solar panel and just need to settle on the choice of Victron MPPT charge controller.

My question is if I want to get the most amps back into my battery should I go for the larger capacity Victron brand MPPT 100/30 charger controller in the following 2 choices below if my solar panel max power current Imp = 9.76A ?? or is the 9.76A the most that I will be able to put back in which case the 75 / 15 unit would suffice?

1. Victron charge controller MPPT 75 /15 rated at 15A
2. Victron charge controller MPPT 100/30 rated at 30A

Thanks in advance

 

[12vDC]

For a 200W panel, you can realistically expect 12A going into the battery under better conditions. You would be reaching the upper end of the 75/15 at the day max but it would work.

The 100/30 might run a little cooler and would allow expansion or upgrading panel(s) later.

 

[Johnny Nova]

For a 200W panel, you can realistically expect 12A going into the battery under better conditions. You would be reaching the upper end of the 75/15 at the day max but it would work.

The 100/30 might run a little cooler and would allow expansion or upgrading panel(s) later.

Ok thanks for clarifying that.
I wasn't sure if the Amps pumped back in was related to the rating of the MPPT or the solar panel.

 

[Sparks99]

Ok thanks for clarifying that.
I wasn't sure if the Amps pumped back in was related to the rating of the MPPT or the solar panel.

12vDC is correct, that's a small panel and won't produce much power. If you get 150W out of it (say) then 150W/13.5V = 11A into the battery (approx, ignoring losses). Your MPPT controller/charger can't deliver more power into the battery than the panels can provide (less, in fact) so there's no point in buying a huge charge controller, its capacity will be wasted and in fact it will draw a greater electronics current so for low input powers it will be less efficient than a sensibly sized one.
I'd also go for the 30A unit, Victron gear has a habit of thermally throttling so you don't want to be running it close to its limit or you may have to add forced cooling just to get the rated current out of it.
If you can pocket it, consider upgrading the panel to a higher quality monocrystaline one with a higher output, it will be money well spent. There are often good deals to be had on stock clearance or sub-spec ones which are still good panels. The main system limiting factor is usually the panel.

 

[Tomthumb62]

You don’t mention your loads or other charging sources.

But I would recommend the 100/30. Why? I have a 200Ah battery, the 100/30 and 4x100W panels. Another 2x100w on the ground when we’re camped in a good spot to deploy them.

90% of our load is running a fridge. 400W can keep up much of the time, but the total of 600W comes in handy. In September near the 45th north, we got 390W out of those 600W of panels. Angle matters and most of ours are flat.

What I’m saying here, you’re likely going to want more panels unless you list what your loads are (and if your think those might ever increase) and we can help you make a more informed decision.

 

[Johnny Nova]

You don’t mention your loads or other charging sources.

But I would recommend the 100/30. Why? I have a 200Ah battery, the 100/30 and 4x100W panels. Another 2x100w on the ground when we’re camped in a good spot to deploy them.

90% of our load is running a fridge. 400W can keep up much of the time, but the total of 600W comes in handy. In September near the 45th north, we got 390W out of those 600W of panels. Angle matters and most of ours are flat.

What I’m saying here, you’re likely going to want more panels unless you list what your loads are (and if your think those might ever increase) and we can help you make a more informed decision.

You don’t mention your loads or other charging sources.

But I would recommend the 100/30. Why? I have a 200Ah battery, the 100/30 and 4x100W panels. Another 2x100w on the ground when we’re camped in a good spot to deploy them.

90% of our load is running a fridge. 400W can keep up much of the time, but the total of 600W comes in handy. In September near the 45th north, we got 390W out of those 600W of panels. Angle matters and most of ours are flat.

What I’m saying here, you’re likely going to want more panels unless you list what your loads are (and if your think those might ever increase) and we can help you make a more informed decision.

Hi thanks for your reply
The main loads we plan to run are only a small 25 L Dometic fridge which quotes 0.92 Ah/h and Sirroco fan drawing 0.35A for possibly 8 hr period during hot summer nights. For lights we use small AA butteries running a string of fairy lights and that’s about it. The plan is to see how long a 200Ah lithium battery will work with the 200W solar panel charging as best as it can a loads quoted above.

 

[E. Cho]

And what will you do when there is no direct bright sunshine? Your travels could be influenced or dictated by weather forecasts and or finding the perfect campsite with no tree shading and no clouds and constant direct sun. Is that realistic or desireble? More panels with more watts / amps will help take advantage of short charging opportunities but not say cloudy days or shading or long thin wire runs and 12 volts.

Ir is very common to only plan system builds for ideal perfect sunny days with ideal perfect panels and angles and short wire distances and no wind, no tree or building shading, no cloudy days, no hot humid days, ideal parking spots, no noise and so on. Getting by with the minimum required in perfect sun and other conditions may not work well in the constant variables of the real world? Having more data of the variables could help planning? Solar means direct sun, not shade or any clouds or haze and efficiency drops as heat increases.

 

[littleharbor2]

If those ah quotes are in 120 vac numbers then you have a 10 to 1 factor to deal with. the fridge will draw 9.2 amps from your battery and your fan, 3.5 amps.

 

[chrisski]

I reccomend the 75/15. I have one of those which I use on a solar generator. I use this every week or two and it runs at 15 amps for hours on end. THe only time I've had it throttle back thermally is when the MPPT was exposed to the sun. I shade it now and even at 115F outside temp, it runs at 15 amps.

The other reason I think a 75/15 may be better is I don't see it powering a 200 ah battery very well and with limited space on a van roof, the next step may be putting out a couple of portable panels with a seperate charge controller.

IF you can fit a second panel on the roof at a later date, the 100/30 would be better for expansion.

 

[Bill Mac]

Hi
I'm planning a small campervan setup using a 200Ah battery powered by just one 200W solar panel and just need to settle on the choice of Victron MPPT charge controller.

My question is if I want to get the most amps back into my battery should I go for the larger capacity Victron brand MPPT 100/30 charger controller in the following 2 choices below if my solar panel max power current Imp = 9.76A ?? or is the 9.76A the most that I will be able to put back in which case the 75 / 15 unit would suffice?

1. Victron charge controller MPPT 75 /15 rated at 15A
2. Victron charge controller MPPT 100/30 rated at 30A

Thanks in advance

Choose the 100/30 Smart Blue tooth Version ( Always over size with expansion Capability.)
Victron is a solid choice with warranty.
These units come with removable fuses. Scan code and down load the app on face plate of unit.
Set battery type and parameters.

Typical PV wires are 10 AWG others are 8 AWG can handle bigger arrays.

Aims 100/30
The wire from charge controller to battery accepts 6 AWG ( do not go smaller ) undersized wires = resistors thus heat = power loss.
200 watt PV Insert a 15A DC breaker on PV Hot lead from CHARGE CONTROLLER to BATTERY. Should handle Higher PV voltage cold conditions

Battery to Inverter copper wire install (inverter amp draw matters) wire gauge reference.
Use size: 2awg 130amp 1/0awg 170amp or 2/0awg 195amp or 3/0awg 225amp or 4/0awg 260amp Cable for DC application.
Use basic Ohms law math for Amp divided by volts = watts for the inverter size used apply wire gauge here.

Solder all wire unless a cold compression Crimp type is fitted ( turning strands into blocks conformed to lugs) to ensure full wire contact
or use the best profession crimping method available to you to avoid power loss and resistance.

Battery to inverter fusing is suggested to be 125% of total inverter amp draw. This is complex due to inverter quality.
We NEVER Use / go over 75% of the inverters rating in power draw on Low Frequency Pure sine wave types. Longevity issue.
My wife insist on using the microwave while the Air Fryer is chugging away. ( Eye twitch ) Granted my systems a beast but still...

Modified sine / High frequency inverters terrify me ( that is all to say here. )
I cannot make any suggestions here when dealing with them.
Normally made cheap / affordable and cannot make 75% or even 50% of their rating continuous duty in my experience.
Insert AD here!!! ( " Quanjo professional make you feel good happy life 4000w modified sine wave run whole house!)<- no, just no.

Must use some type of copper wire corrosion inhibitor on all terminals ( Please step up advanced solar installers to help me here.)
I use dielectric grease because I'm poor. There are better options out there. I'm at least trying here.
Please correct me if anything is wrong of off. Hope this helps. You got this!

Hi
I'm planning a small campervan setup using a 200Ah battery powered by just one 200W solar panel and just need to settle on the choice of Victron MPPT charge controller.

My question is if I want to get the most amps back into my battery should I go for the larger capacity Victron brand MPPT 100/30 charger controller in the following 2 choices below if my solar panel max power current Imp = 9.76A ?? or is the 9.76A the most that I will be able to put back in which case the 75 / 15 unit would suffice?

1. Victron charge controller MPPT 75 /15 rated at 15A
2. Victron charge controller MPPT 100/30 rated at 30A

Thanks in a

 

[MiSh]

FWIW, Most campers run the fridge off their propane. If you run it off the battery it will be dead in no time. 3way refrigerators sip the propane when running.

 

[Johnny Nova]

If those ah quotes are in 120 vac numbers then you have a 10 to 1 factor to deal with. the fridge will draw 9.2 amps from your battery and your fan, 3.5 amps.

Hi
Just saw your comment and was wondering what you meant by........"120 vac numbers then you have a 10 to 1 factor to deal with" ???

Also are you quoting the total amp draw for fridge and fan for a 24 hr period?

 

[littleharbor2]

Hi
Just saw your comment and was wondering what you meant by........"120 vac numbers then you have a 10 to 1 factor to deal with" ???

Also are you quoting the total amp draw for fridge and fan for a 24 hr period?

If you are drawing that current from a 12 volt battery and inverting it to 120 volts ac then you need to multiply the amp hours by 10. 12 volts - 120 volts, get it.
I see you are in Australia and aren't sure what voltage you use down under but if higher than 120 volts, the 10 to 1 factor gets worse.

 

[Johnny Nova]

If you are drawing that current from a 12 volt battery and inverting it to 120 volts ac then you need to multiply the amp hours by 10. 12 volts - 120 volts, get it.
I see you are in Australia and aren't sure what voltage you use down under but if higher than 120 volts, the 10 to 1 factor gets worse.

Ok thanks. 230V household mains voltage used here. No plans to use an inverter at this stage. Just small 25L fridge, fan and phone charging