MPPT VS PWM

[Techno]

Nice analogy @Guigsy

 

[Diabalo]

Do the lunar panels benefit in the same way as the daylight panels with a MPPT controller?

 

[eddie]

Do the lunar panels benefit in the same way as the daylight panels with a MPPT controller?

No to get the most out of Lunar Panels you have to use a "Oh Please!" regulator

As in you look up at the amount of Moonlight, see how much your Lunar panel is producing and shout "Oh Please!"

 

[hilldweller]

Don’t open the lauded Schaudt

A resistor and a zenner diode ?

 

[Minxy]

Okay, being serious for a minute or two (difficult I know!) ...

In the 'real' world how much benefit does for example a Schaudt LRM1218 (MPPT) one give over a LR1218 (PWM) one? The PWM is about £70, the MPPT about £170, so what do you actually get for that extra £100 and would using a PWM one with an extra panel be more effective?

eg for the about the same cost you could have:

• a PWM controller and 2 x 100w panels
  OR
• a MPPT controller and a 100w panel

I suspect in the overall scheme of things you'll get more input from the PWM set-up than the MPPT set-up even though the latter can 'manage' the input better.

Has anyone any info on the stats to prove this one way of the other?

^{_{Subscribers  do not see these advertisements}}

 

[canopus]

Minxy don't you have any shopping to do or new van to titivate?

 

[hilldweller]

Has anyone any info on the stats to prove this one way of the other?

I've been asking for many pages now but in reality all we have are "impressions". And that is all we can expect, to do an accurate test would require a variable intensity light and a great deal of time.

My take is, only those keen types out in winter will benefit, in any weather we'd want to be camping there is no real difference.

 

[Minxy]

Minxy don't you have any shopping to do or new van to titivate?

 

[funflair]

Okay, being serious for a minute or two (difficult I know!) ...

In the 'real' world how much benefit does for example a Schaudt LRM1218 (MPPT) one give over a LR1218 (PWM) one? The PWM is about £70, the MPPT about £170, so what do you actually get for that extra £100 and would using a PWM one with an extra panel be more effective?

eg for the about the same cost you could have:

• a PWM controller and 2 x 100w panels
  OR
• a MPPT controller and a 100w panel

I suspect in the overall scheme of things you'll get more input from the PWM set-up than the MPPT set-up even though the latter can 'manage' the input better.

Has anyone any info on the stats to prove this one way of the other?

Out of your two proposed schemes the PWM and 2x100w would give the best output BUT I would not do it that way I would use a Votronic 250MPPT duo at £120 and 2x100w panels giving more output than either of your options for only £50 more

Martin

 

[Minxy]

Out of your two proposed schemes the PWM and 2x100w would give the best output BUT I would not do it that way I would use a Votronic 250MPPT duo at £120 and 2x100w panels giving more output than either of your options for only £50 more

Martin

Another option but would that give more output than say the 2 x 100w, an extra 50w panel and the PWM controller ... nobody knows and that's the problem! Its a minefield! Why is nothing simple with MHs!

^{_{Subscribers  do not see these advertisements}}

 

[funflair]

I've been asking for many pages now but in reality all we have are "impressions". And that is all we can expect, to do an accurate test would require a variable intensity light and a great deal of time.

My take is, only those keen types out in winter will benefit, in any weather we'd want to be camping there is no real difference.

Just run two systems side by side and back the inverter and microwave on, you will see the difference at all times of the year.

Martin

 

[funflair]

Another option but would that give more output than say the 2 x 100w, an extra 50w panel and the PWM controller ... nobody knows and that's the problem! Its a minefield! Why is nothing simple with MHs!

At that I think they would be pretty close but the 2x100w and MPPT could quite possibly win especially in lower light, then of course the extra weight and the cost of 4 more feet for the 50w panel would put it over so MPPT wins again

I know which way I would go anyway

Martin

 

[Burgo]

I'm finding this informative but wondering still if 'best practice' is to wire regulator direct to battery / ies or to wire through the elektroblock?

 

[tacr2man]

My technical understanding of the difference between MPPT vs PWM is (which is probably wrong):

If you don't connect significant load to a solar panel, it's voltage is pretty high (and gets higher as it gets brighter), but as you put load on it and pull more current, the voltage sags down. Voltage x current gives you power.

PWM controllers have a fixed load which they pulse on and off extremely quickly. This is dumped into capacitors to smooth out the power and get it down to the appropriate level to charge your battery. Once light levels get too low, the voltage sag under load gets too much and PWM stops providing juice.

MPPT controllers can actively adjust the load (and still do some PWM and capacitor tricks) on the solar panels. On nice sunny days, they pull the most load they can, just like cheaper PWM controllers. As light levels drop, they reduce the load so the solar panels' voltage doesn't sag as much so there's still a bit of power to be drawn. Basically they have much better efficiency in lower light.

MPPT is a bit like having gears in the van. When it gets steep (lower light), you can change down gears. You don't go as fast, but you still get somewhere. PWM only has a 6th gear.

It surprised me the voltage on the panels for example its raining and overcast this morning and the panels are showing 83Volts. going to the mppt , i have seen 109v on one of the two sunny days Ive had since installation

 

[Minxy]

I'm finding this informative but wondering still if 'best practice' is to wire regulator direct to battery / ies or to wire through the elektroblock?

I suspect it depends on what going through your electroblock will give you, some mean the hab and cab batteries will be kept topped up with the solar, whereas if you go direct to the hab batteries obviously your cab one won't be charged unless you have a bit of kit linking it. Also if you have an existing display which allows you to monitor your solar input this would usually need it to go through the electroblock.

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Lenny will confirm we have seen high charge amps even in almost foggy conditions. Like I did as pictured in Holland the other year

Fair comment but its not right to claim a PWM can deliver as well as an MPPT it is simply not possible

With the same regulator Andy uses I was getting 25 watts from 200 watts of panels in these conditions.

 

[Minxy]

With the same regulator Andy uses I was getting 25 watts from 200 watts of panels in these conditions.

View attachment 227738

Not disputing your or Andy's views for one minute but would welcome your view on how you think a PWM would have coped, I've no idea.

 

[hilldweller]

Another option........................

Get back into the real world. You aren't going to die due to this. The weather rules, if it wants to make you miserable and wish you never owned a MH it can and it will.

Now lets get thinking showers, if you fall down a hole in the shower that is getting serious.

 

[eddie]

A resistor and a zenner diode ?

I'll send you a picture on Monday when I am back in work

 

[Lenny HB]

Not disputing your or Andy's views for one minute but would welcome your view on how you think a PWM would have coped, I've no idea.

Same conditions you would get zero output. My first regulator was a Schaudt LR1218 in conditions far better than the photo got no output & the LR1218 is probably one of the best PWM regulators it has circuitry to boost the voltage in low light conditions.

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Okay, being serious for a minute or two (difficult I know!) ...

In the 'real' world how much benefit does for example a Schaudt LRM1218 (MPPT) one give over a LR1218 (PWM) one? The PWM is about £70, the MPPT about £170, so what do you actually get for that extra £100 and would using a PWM one with an extra panel be more effective?

eg for the about the same cost you could have:

• a PWM controller and 2 x 100w panels
  OR
• a MPPT controller and a 100w panel

I suspect in the overall scheme of things you'll get more input from the PWM set-up than the MPPT set-up even though the latter can 'manage' the input better.

Has anyone any info on the stats to prove this one way of the other?

Its not just about PWM & MPPT regulation with the Schaudt units.
The LR1218 is really only suitable for Gel batteries, that is what it was designed for. Once it reaches the charged voltage of 14.2v it maintains that voltage constantly, which will fry most batteries apart from Gels.

The LRM1218 has a proper 3 stage charger giving a bulk charge an absorption phase and a float charge & adjustable for Gel, wet cells & AGM.
If you are looking at getting a LRM1218 better to spend your money on a Victron or Votronic

 

[Lenny HB]

Another option but would that give more output than say the 2 x 100w, an extra 50w panel and the PWM controller ... nobody knows and that's the problem! Its a minefield! Why is nothing simple with MHs!

Still not going to work as well in the winter that is where MPPT controlers win hands down & 50 watt panels are not very cost effective nearly as dear as 100 watt panels then there is avalible space to fit them.

 

[Lenny HB]

Isn't there another variable in the equation, insofar as to whether the regulator is connected directly to the battery/ies, or connected via an Elektroblock? Just wondering if that could make a difference??

Solar connections on Elektroblocks are just straight through connections to the batteries just makes it easy to wire the solar into the system.

 

[Richard n Ann]

My first panel was a Bosch 40w with a PWM steca regulator. It produced nothing unless the sun was directly shining on it, even a bright day with white clouds.. Nothing.

 

[eddie]

If we get time next week i'll get one of our guys to set up two or three panels and meter everything up

We keep a range of PWM regulators in the shop, like a rouges gallery of crap so we will be able to provide some figures, not that anyone will take any notice as there has already been posts quoting before and after figures.

However, if a man has two panels on his roof and doesn't want to or can't add another panel and simply wants to replace a broken regulator, and asks the question which is better, MPPT or PWM the answer is MPPT

If the question was which is the cheapest, it would be different aanswer

If he felt confident enough to tackle the installation of a third panel as an option, he probably wouldn't have asked the question in the first place as he would have known.

Why buy a motorhome when you can buy a tent, its cheaper and apparently that is the most important thing!

To some!

^{_{Subscribers  do not see these advertisements}}

 

[Minxy]

Its not just about PWM & MPPT regulation with the Schaudt units.
The LR1218 is really only suitable for Gel batteries, that is what it was designed for. Once it reaches the charged voltage of 14.2v it maintains that voltage constantly, which will fry most batteries apart from Gels.

The LRM1218 has a proper 3 stage charger giving a bulk charge an absorption phase and a float charge & adjustable for Gel, wet cells & AGM.
If you are looking at getting a LRM1218 better to spend your money on a Victron or Votronic

Thanks Lenny, interesting ... now having investigate the camper more we have discovered we have 2 new 100ah Lion leisure batteries installed which are like the below, they're not 'standard' wet batteries as they have 'calcium' in them (sealed) so are apparently 'deep cycle' ones ... but I'm now at a loss as to what controller I should use to connect my solar panels:

According to the blurb for the LR1218 it says:

If the solar modules have sufficient charging voltage, the solar charge regulator allows the battery to be charged by up to 14.2 V. As soon as these voltage is reached, the charging current is reduced to fully charge the batteries without impairing them. If the charging voltage of the solar modules is insufficient (e.g. in the dark), an integrated isolation diode prevents the batteries from discharging.
​

So IS a LR1218 suitable for my batteries or not bearing in mind it does 'reduce'?

 

[Diabalo]

Comfy chair out and bucket of popcorn , I'm ready

 

[Lenny HB]

Thanks Lenny, interesting ... now having investigate the camper more we have discovered we have 2 new 100ah Lion leisure batteries installed which are like the below, they're not 'standard' wet batteries as they have 'calcium' in them (sealed) so are apparently 'deep cycle' ones ... but I'm now at a loss as to what controller I should use to connect my solar panels:

View attachment 227833

According to the blurb for the LR1218 it says:

If the solar modules have sufficient charging voltage, the solar charge regulator allows the battery to be charged by up to 14.2 V. As soon as these voltage is reached, the charging current is reduced to fully charge the batteries without impairing them. If the charging voltage of the solar modules is insufficient (e.g. in the dark), an integrated isolation diode prevents the batteries from discharging.
​

So IS a LR1218 suitable for my batteries or not bearing in mind it does 'reduce'?

Current is reduced but that would happen with any charger as the internal resistance of a battery increases as it reaces a fully charged state, the problem with the LR1218 is that the voltage doesn't reduce to a maintainance charge.

I thought you were getting another German van so why are you getting Lion batteries I always think as then as cheap & chearful. Also I think you will find they are just a rebadged starter batteries.
I know you do a lot of off grid camping so why not fit a couple of decent batteries. Also if the van has an Elektroblock the latest ones only have setting for Gel & AGM and will probably fry the Lion's. The AGM setting charges at 14.7v which is too high for wet cells & with the Gel setting the absorption phase is 16 hours again will probably fry the Lion's.

As for solar regulator I would go for either a Victron or Votronic MPPT my personal choice would be the Votronic maybe because I have one and they are a bit cheaper a 250 watt around £115 & 350 watt £165.

 

[funflair]

A few words pinched off the internet,

Martin

A Calcium battery is a still a lead acid battery; they are usually sealed maintenance free. Calcium replaces antimony in the plates of the battery to give it some advantages including improved resistance to corrosion, no excessive gassing, less water usage and lower self discharge. Silver is another additive used by some manufacturers, the addition of silver enables the battery to be more resilient to high temperatures.

Calcium batteries require a higher charge voltage than conventional batteries. If used in a deep cycle situation it is advisable to use a charger designed for calcium batteries of has a calcium charging mode to get the maximum life out of the battery.

 

[Minxy]

Current is reduced but that would happen with any charger as the internal resistance of a battery increases as it reaces a fully charged state, the problem with the LR1218 is that the voltage doesn't reduce to a maintainance charge.

So when it says it 'reduces' after the battery is fully charged, would that be the 'maintenance charge' or a different charge?

I thought you were getting another German van so why are you getting Lion batteries I always think as then as cheap & chearful. Also I think you will find they are just a rebadged starter batteries.

That's what the dealer put in when we told him we wanted 2 leisure batteries. After all the talk of AGM batteries failing I wasn't that bothered that he hadn't fitted a second AGM and though it might be better to have the ones we have.

I know you do a lot of off grid camping so why not fit a couple of decent batteries.

I can't see the point of throwing out 2 new batteries for the sake of it, if they give me grief then maybe but I suppose only time will tell.

Also if the van has an Elektroblock the latest ones only have setting for Gel & AGM and will probably fry the Lion's. The AGM setting charges at 14.7v which is too high for wet cells & with the Gel setting the absorption phase is 16 hours again will probably fry the Lion's.

I've got a Schaudt EBL 119 in the new camper which says it charges as follows, am I right to assume that 'lead-gel' means it is suitable for lead OR gel?:

As for solar regulator I would go for either a Victron or Votronic MPPT my personal choice would be the Votronic maybe because I have one and they are a bit cheaper a 250 watt around £115 & 350 watt £165.

Thanks, I really want to understand it all first before I plump for anything, not doubting you at all, I just don't like to put stuff in without knowing how/why it works as it does and that it's definitely the option I want to go for.

So ... trying to understand everything:

My Schaudt EBL119 Elektroblok has a setting for lead-gel so it appears won't necessarily 'fry' my Lion Calcium-Calcium batteries as they need a higher charge rate than standard lead acid ones ... have I got that right or wrong?

It appears that the LR1218 solar controller, whilst not ideal for standard lead batteries, shouldn't cause issues with my Calcium-Calcium batteries (assuming the reduced charge is the maintenance charge as mentioned above) - is that correct?

I've tried researching on the web but its still a bit confusing.

^{_{Subscribers  do not see these advertisements}}