MPPT vs PWM cotrollers?

[john61ct]

Originally Posted by missourisailor

Also most manufacturers, retailers and experienced installers recommend a controller for each panel to deal with shading issues.

I haven't come across a single one that does.

When I started advising this last year, I got a lot of pushback, and in other forums still do.

It is certainly far from mainstream advice.

[wiekeith]

Originally Posted by missourisailor

Also most manufacturers, retailers and experienced installers recommend a controller for each panel to deal with shading issues.

I must confess that I've never understood this approach. I'm not saying you're wrong, just that I can't get my head around it.

Let's say we have two panels with two controllers, A and B. A is in sunlight, B is in shade. A applies 14v, say, because of batteries low state of charge, B comes out of shade, sees battery voltage of 14v so just applies a float charge, hence 'wasting' the available charge from its panel.

That's an extreem example I know, but by my simple logic (which may be incorrect) it would apply in all cases i.e. whichever controller reacts first will cause the other(s) to back off.

I'm open to being persuaded that I'm wrong on this one

[hasse_A]

If you have a SSB or HAM radio on board you should be very cautious installing MMPT-regulators. I had 2 different brands both having fatal levels of RFI.
One of them was a 20 A Epever tracer, pictured in this thread.
I threw both out and replaced them with Morningstar PWM-regulators and they seem to be very quiet.
I have talked to several cruisers having difficulty with interference from MPPT- regulators killing their reception on the HF-bands.
I am not saying all PWM-regulators are quiet. Some may well not be, as these regulators also switch current.

[GTom]

Originally Posted by hasse_A

If you have a SSB or HAM radio on board you should be very cautious installing MMPT-regulators. I had 2 different brands both having fatal levels of RFI.
One of them was a 20 A Epever tracer, pictured in this thread.
I threw both out and replaced them with Morningstar PWM-regulators and they seem to be very quiet.
I have talked to several cruisers having difficulty with interference from MPPT- regulators killing their reception on the HF-bands.
I am not saying all PWM-regulators are quiet. Some may well not be, as these regulators also switch current.

Any feedback on the SSB compatibility of Victrons? SSB is one of the most power hungry stuff after aircons and freezers, I wouldn't want to turn off solar when on SSB...

[hasse_A]

Originally Posted by GTom

Any feedback on the SSB compatibility of Victrons? SSB is one of the most power hungry stuff after aircons and freezers, I wouldn't want to turn off solar when on SSB...

Yeeh, and to turn those off you would, if you comply with the manufacturers manual, need to first disconnect the panels and then the regulators.
The regulators don't like to have the solar panels attached if the batteries are not. This can be done with relays and a micro controller but who would go through the hassle of building such a device ?
It's better to find non RFI regulators.

My MPPT-regulators still generated a lot of RFI even with the solar panels where disconnected.

[john61ct]

Originally Posted by wiekeith

I'm open to being persuaded that I'm wrong on this one [emoji2]

I don't have a general theoretical reason, but in practice doesn't happen.

Any number of separately regulated charge sources of any type can be concurrently stacked in parallel on a bank, and it will get charged faster at a higher amp rate, nothing is harmed or wasted.

Ideally they would have similar charge profile settings but NP if they don't.

Just because one sees a higher voltage does not mean it instantly drops to float. Good SCs are fully adjustable anyway, so even if that happened you just change the minimum Absorb Hold Time and Bob's your uncle.

Finally many SC model lines can be connected in an array so their charge output is coordinated, either master-slave from one of the units, or from a separate central monitoring unit.

[john61ct]

Couldn't a cheap enclosure act as a Faraday cage?

[GTom]

Originally Posted by john61ct

Couldn't a cheap enclosure act as a Faraday cage?

An RF specialist might chime in, but I suspect the cables towards the panels would leak out the noise. Have to budget in shielded coax cables too for a cheap MPPT controller, to continue operating that 3k$ worth SSB set

[john61ct]

There are plenty of noisy units that are expensive too.

Probably worth starting a new thread for the topic

[hasse_A]

Originally Posted by john61ct

Couldn't a cheap enclosure act as a Faraday cage?

Maybe, but you probably would need to filter the power lines also. Otherwise they will pass the interference out of the box. These lines go a "far" distance since you probably do not want to place the solar panels in the locker where the batteries are located. The power lines will act as antennas broadcasting the Radio Interference. If serious they can also enter the power input to the Radio.

[wiekeith]

Originally Posted by john61ct

Probably worth starting a new thread for the topic

I'd be interested in that. Not used my SSB in anger since fitting the solar system, but going to need it later this year.

[missourisailor]

Originally Posted by john61ct

Bypass diodes are for the shade issue, not blocking diodes, and used for serial'd panels not parallel.

Blocking diodes aren't usually needed these days, built into SCs.

Thanks for the insight. I know the difference between the two and used the correct name for the application.

[missourisailor]

Originally Posted by john61ct

I haven't come across a single one that does.

When I started advising this last year, I got a lot of pushback, and in other forums still do.

It is certainly far from mainstream advice.

Well you for one.
Victron and Genasun for two and three.

Far too many retailers to mention.

Not far from mainstream. More like mainstream.

[missourisailor]

Originally Posted by wiekeith

I must confess that I've never understood this approach. I'm not saying you're wrong, just that I can't get my head around it.

Let's say we have two panels with two controllers, A and B. A is in sunlight, B is in shade. A applies 14v, say, because of batteries low state of charge, B comes out of shade, sees battery voltage of 14v so just applies a float charge, hence 'wasting' the available charge from its panel.

That's an extreem example I know, but by my simple logic (which may be incorrect) it would apply in all cases i.e. whichever controller reacts first will cause the other(s) to back off.

I'm open to being persuaded that I'm wrong on this one

The one thing that you are overlooking is that when you start to charge, the battery will drag the voltage down to...whatever. Untill the current starts to drop. Then the voltage will began to rise.

Because of this, all charging sources will see the lower voltage and contribute to the charge.

Samething happens when on shore power and you start the engine. If the battery is in a discharged state, both will try to charge.

[conachair]

Originally Posted by GTom

Any feedback on the SSB compatibility of Victrons? SSB is one of the most power hungry stuff after aircons and freezers, I wouldn't want to turn off solar when on SSB...

Just had a look with a fun cube dongle into sdr#.

Couldn't tell any difference between a 75/10 on or off @ 8Mhz.

Shame the fridge wasn't as well behaved.