MPPT VS PWM

ShiftZZ

ShiftZZ

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I have 2 x 100W solar and 2 x 100AMP batteries the 'controller' needs replacing..

Suggestions?
 
People will tell you to go MPPT due to the 'better' charging regime/input but the cost of it over a standard one means you could probably fit another solar panel instead and be quids in. :D
 
Minxy Girl said:
People will tell you to go MPPT due to the 'better' charging regime/input but the cost of it over a standard one means you could probably fit another solar panel instead and be quids in. :D
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Not strictly true Minxy. Fiitting a new solar panel will be futile if the existing controller isn't man enough, plus the existing cabling from roof to batteries may need increasing to carry the output of 3 solars.
 
canopus said:
Not strictly true Minxy. Fiitting a new solar panel will be futile if the existing controller isn't man enough, plus the existing cabling from roof to batteries may need increasing to carry the output of 3 solars.
Click to expand...
Not strictly untrue though ... as with all things it depends on the existing set-up and what's required.
 
A good quality MPPT regulator works far better, I recently fitted a Votronic regulator (MPP 350) having seen the results I wouldn't fit anything else now.

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Minxy Girl said:
People will tell you to go MPPT due to the 'better' charging regime/input
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Yes they will probably posting this on an iPhone. But just how much better in the real world ? Most definitely not better than your proposed upping the solar panels by a half.

I've just fitted a simple PWM one. I'll live with that. In some apologetic Southport haze it was putting 3.6A into the battery from the 200W panel.
 
Lenny HB said:
A good quality MPPT regulator works far better, I recently fitted a Votronic regulator (MPP 350) having seen the results I wouldn't fit anything else now.
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But can you produce meaningful before/after figures ?
 
Forgot to mention in previous post , you can also setup so that load goes thru MPPT controller , which allows setting cut off voltages for drain when solar not operating . It also shows whats going in to system and what is coming out separately . HTSH

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Both PWM and MPPT have a critical light level under which the controller will not provide any charge. With PWM the light levels have to be pretty high or you get zero. MPPT can adjust charging demand to balance the solar panel so you can keep squeezing power out under lower light conditions or when the sun is lower in the sky.

On a cloudless summers day, by sunset, PWM will have produced roughly the same amount of charge as MPPT. There won't be much in it. On a cloudly day in late autumn, MPPT will have pumped a fair few AH into the battery whereas PWM might not have given you anything.
 
hilldweller said:
But can you produce meaningful before/after figures ?
Click to expand...
Due to constant variation of the suns brightness, you would need a laboratory set up to produce accurate results. However I noticed a maked differance between my previous good quality MPPT regulator and the new Votronic one I just fitted and reckon it was well worth the £160.
Previously in Spain with 200 watts of panels the best I got during March was 95 watts, my current setup is 300 watts of panels with the Votronic unit and this March I often achieved 160 - 170 watts, that relates to a 15 - 20% increase.
 
Surely that's worse if you divide the panel by what it's producing, mind you mafs was never my strong suit, english ain't much better
 
Minxy Girl said:
Not strictly untrue though ... as with all things it depends on the existing set-up and what's required.
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Dave's already told us what we need to know. He has two panels and needs a new regulator. MPPT

I have three 150 watt panels on my camper and they are wired so I can easily make comparison between three different regulators simultaneously

MPPT is definitely worth the extra

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eddievanbitz said:
I have three 150 watt panels on my camper and they are wired so I can easily make comparison between three different regulators simultaneously

MPPT is definitely worth the extra
Click to expand...

I like numbers, have you ever done instant switch over and logged the results ?
 
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Lenny HB said:
Due to constant variation of the suns brightness, you would need a laboratory set up to produce accurate results. However I noticed a maked differance between my previous good quality MPPT regulator and the new Votronic one I just fitted and reckon it was well worth the £160.
Previously in Spain with 200 watts of panels the best I got during March was 95 watts, my current setup is 300 watts of panels with the Votronic unit and this March I often achieved 160 - 170 watts, that relates to a 15 - 20% increase.
Click to expand...

You'd need two identical systems, side by side, using different controllers but the same load to get a ‘proper’ comparison.

Interesting that your panels don't reach their claimed output.
Maybe the batteries were charged up, or you were just too far from the equator (insufficiently perpendicular to the sun)?
Do you know if the panels ever 'max-out' for part of the day?
I think there may be a point at which they cannot produce any more, before the sun is at its highest.
 
rogher said:
Interesting that your panels don't reach their claimed output.
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They are never going to do that with the angle of the sun in March, over 50% is pretty good going for the time of year I was well impressed.
Easy to get 100% out of flat mouted panels in June even with a poor regulator but that's not when we need the power, a good regulator comes into its own with lower sun angles and dull skyes.
 
hilldweller said:
I like numbers, have you ever done instant switch over and logged the results ?
Click to expand...
Hi Brian, with having three identical panels, all installed side by side I can easily test any regulator against what I have found to be my "gold" sample the Victron MPPT

Some of the cheaper PWM Chinese nasties that float around screen printed with different names on can be appalling. The worst I have seen was 2.2amps - 4.10amps - 4.08 amps side by side simultaneous tests across the three panels

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i have just set up a 100w solar panel with this controller Amazon product ASIN B075XFLVPYand fitted a compressor fridge although i havent used this setup in anger yet, just standing in the yard with the fridge on in rainy uttoxeter weather , its keeping the fridge working and by 10 o clock its showing the batterys at 13. 8 volts.
seems ok to me.
 
eddievanbitz said:
Hi Brian, with having three identical panels, all installed side by side I can easily test any regulator against what I have found to be my "gold" sample the Victron MPPT

Some of the cheaper PWM Chinese nasties that float around screen printed with different names on can be appalling. The worst I have seen was 2.2amps - 4.10amps - 4.08 amps side by side simultaneous tests across the three panels
Click to expand...

Interesting, Eddie, but what do those figures mean? I assume they are the output from three different controllers, but which ones&types? Have you compared a Victron model alongside a Votronic?

The measurement I’m interested in is the power that can be obtained from a panel at various levels of incidence, but no-one seems able to provide it.
All panels will work to a degree but some actual data would be useful to determine what size to get.
 
Minxy Girl said:
People will tell you to go MPPT due to the 'better' charging regime/input but the cost of it over a standard one means you could probably fit another solar panel instead and be quids in. :D
Click to expand...

canopus said:
Not strictly true Minxy. Fiitting a new solar panel will be futile if the existing controller isn't man enough, plus the existing cabling from roof to batteries may need increasing to carry the output of 3 solars.
Click to expand...

Dave said his controller needs replacing....and asked for suggestions as to which type.
 
Even comparing chargers side-by-side might be tricky. MPPT chargers tend to be smarter (and kinder) with the battery, so you might find it's pushing less into a battery because it's nearly charged.

For instance, at the moment my van has been sitting on the drive for a few weeks while it gets various modifications. The battery is pretty much charged up. The MPPT charger rarely shows more than 5% of the panel's maximum capacity being trickled into the battery in even the brightest sunlight. However, if I turn on the pump, it'll respond by pushing more juice, offsetting the demand pretty precisely. The most basic PWM chargers don't do this, they just ram in what they can until the voltage reaches a certain level.
 
pappajohn said:
Dave said his controller needs replacing....and asked for suggestions as to which type.
Click to expand...

The his big mistake, he should know better, was to ask on here.

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