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MPPT controller


Johny London

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Just starting to think about solar as otherwise I'll be missing out on "free" power this summer. Looks like I'll want an mppt type controller and a fairly hefty one at that. 60a Victron coming in at best part of £300, other much cheaper options available so I'm after your thoughts and suggestions, please. It may be that I'll be wanting to start of with one solar panel due to budget constraints and add them as I go - hopefully ending up with several 100/150w panels, or maybe more. That's if I can ever decide between flexi's and rigids. But the ability to just add on more panels would be good. I heard there is a thing called a combiner also? Or do some mppts do that too?

Am I correct in thinking that you can have more power (in terms of panels) than the mppt can use, so it just goes to waste rather than damages anything? As I'm thinking that the main advantage of having lots of panels would be not so much peak output under ideal conditions, but to still get something worthwhile out of them at other times.

thanks

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11 minutes ago, Johny London said:

60a Victron coming in at best part of £300,

300 quid for a 60A Victron sounds like a good price to me. I bought an MPPT (12 Volt) from Taiwan a few years back for 200 quid.

Edited by rusty69
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2 hours ago, Johny London said:

Am I correct in thinking that you can have more power (in terms of panels) than the mppt can use, so it just goes to waste rather than damages anything? As I'm thinking that the main advantage of having lots of panels would be not so much peak output under ideal conditions, but to still get something worthwhile out of them at other times.

Yes :)

You mustn't exceed the controller's maximum input voltage (ever!) but more power is not a problem. 

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Oh that's good then - I can keep adding panels to get the gloomier days producing something without blowing it all up if the sun comes out!

I presume most mppt controllers that are for 12v batteries would be able to handle the input voltages from most normal solar panels intended for the same. Here's a thought though - can you mix and match panels? I'm assuming they have a diode or similar to stop voltage going into them because in any case you could have two identical ones giving different outputs if one was in the shade... or does it depend on having a "combiner"?

I'd like to hear from anyone with multiple panels.

Another thought - can you just add on extra mppt controllers (with more panels).

Anything wrong with using one of these... at least it would get me up and running...

http://www.ebay.co.uk/itm/LCD-60A-80A-12V-24V-MPPT-Solar-Panel-Charge-Controller-Battery-Regulator-USB-SP-/401165507578?var=&hash=item5d6753dbfa:m:mt-_Rn2Xp8EwTtR0ahasXbQ

Edited by Johny London
Another thought
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You can get a Tracer 40A 100V MPPT plus a monitor and temperature sensor for abou £170. This would be good for a couple of 33V 245W panels, with capacity for one more if needed. 

Mix and match tends not to be advised for some reasons. 

The eBay job seems too good to be true, so something about it won't be right. 

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Mixing is not good, panels in series are limited to the current of the one with the lowest current rating.  For panels in parallel of different voltages at best only one will do any work, the other will just sit there, at worst one will never work again. Also remember panels in series only work well if all are in the sun, panels in parallel to not work as well

in low light as the volts are low, and the current being higher leads to more volt drop for the same size cable.

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2 hours ago, Johny London said:

Oh that's good then - I can keep adding panels to get the gloomier days producing something without blowing it all up if the sun comes out!

I presume most mppt controllers that are for 12v batteries would be able to handle the input voltages from most normal solar panels intended for the same. Here's a thought though - can you mix and match panels? I'm assuming they have a diode or similar to stop voltage going into them because in any case you could have two identical ones giving different outputs if one was in the shade... or does it depend on having a "combiner"?

I'd like to hear from anyone with multiple panels.

Another thought - can you just add on extra mppt controllers (with more panels).

Anything wrong with using one of these... at least it would get me up and running...

http://www.ebay.co.uk/itm/LCD-60A-80A-12V-24V-MPPT-Solar-Panel-Charge-Controller-Battery-Regulator-USB-SP-/401165507578?var=&hash=item5d6753dbfa:m:mt-_Rn2Xp8EwTtR0ahasXbQ

It will be PWM for that pirce.

You can connect controllers in parrallel. I have 3x 250W (in series) through a 60A mppt, and one 250W through a seperate mppt controller

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2 hours ago, rusty69 said:

It will be PWM for that pirce.

You can connect controllers in parrallel. I have 3x 250W (in series) through a 60A mppt, and one 250W through a seperate mppt controller

Just because they're cheap doesnt mean they wont be MPPT, but there may be some innefficiencies:

 

 

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41 minutes ago, Richard10002 said:

Just because they're cheap doesnt mean they wont be MPPT, but there may be some innefficiencies:

 

 

Well, I suppose it's possible you can get a 60A MPPT controller for less than 50 quid. 

The one in the clip is a 10A one and the guy is suggesting that that is less than 50 quid. 

 

I think if you are going to put potentialy large currents through a piece of electronics, particularly if it's to be left unattended you ideally want a quality one. 

Edited by rusty69
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1 hour ago, rusty69 said:

Well, I suppose it's possible you can get a 60A MPPT controller for less than 50 quid. 

The one in the clip is a 10A one and the guy is suggesting that that is less than 50 quid. 

 

I think if you are going to put potentialy large currents through a piece of electronics, particularly if it's to be left unattended you ideally want a quality one. 

I agree, and I think the guy in the clip suggests similar... it is MPPT, but not particular efficient, and it might suit some peoples purpose.

 

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That video set me off on rather an informative session, watching stuff about other mppt controllers, and it seems that these are pretty decent for the money, with several mostly positive reviews...

http://www.ebay.co.uk/itm/new-EPEVER-Tracer-MPPT-12-24V-20-40A-Solar-Charge-Controller-Battery-Regulator-/152268582466?var=&hash=item2373ea2e42:m:m8RrwRBN6BMyqw9JgGk2LmQ

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4 minutes ago, Johny London said:

That video set me off on rather an informative session, watching stuff about other mppt controllers, and it seems that these are pretty decent for the money, with several mostly positive reviews...

http://www.ebay.co.uk/itm/new-EPEVER-Tracer-MPPT-12-24V-20-40A-Solar-Charge-Controller-Battery-Regulator-/152268582466?var=&hash=item2373ea2e42:m:m8RrwRBN6BMyqw9JgGk2LmQ

Hong Kong supplier, and much cheaper than any other I can find... so could be fake, probably take a few weeks to arrive??

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14 minutes ago, Johny London said:

That video set me off on rather an informative session, watching stuff about other mppt controllers, and it seems that these are pretty decent for the money, with several mostly positive reviews...

http://www.ebay.co.uk/itm/new-EPEVER-Tracer-MPPT-12-24V-20-40A-Solar-Charge-Controller-Battery-Regulator-/152268582466?var=&hash=item2373ea2e42:m:m8RrwRBN6BMyqw9JgGk2LmQ

The other 40A tracer, although  a bit more cost, looks like it may be made in the  same factory as the Outback controller (in fact they look the same) 

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I guess it's the same old story - buy cheap buy twice, pay a premium for the best or try and find a middle ground (I think the Epever does the latter).

One last thing - as an alternative route, I could buy one panel (150w ish) at a time, each with a small mppt controller (15A victron readily available around 70/80 quid), which would be cost effective both in the long and short term. Does this route have any advantages? Ie if the panels all have separate controllers and some are in sun and some aren't, it would work better than having all panels on one large controller? Also could be quite a neat way of bringing all the wires together? Or will too many mppts make too much froth?

I'm planning to run in parallel I think, hadn't realised that serial was even an option!

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On 24/04/2017 at 13:18, Jambo said:

This one is a good, cheap 20A one:

http://www.ebay.co.uk/itm/350949943788?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

For every domestic panel you add, add on another one of those and you'll have a pretty cost-effective modular set up.

Actually not to impressed with the specification of this particularly the max open circuit voltage of 15-42 volts for a little more you could get a Tracer, in fact the new cheaper CN model tracer should be available soon, can't say what they are like but I have 3 of the Tracer BN series mppt controllers and and very pleased with them. 

In fact just found link to the new CN series which appear to have a max open circuit voltage of 100volts

http://www.ebay.co.uk/itm/Budget-20A-12v-24v-MPPT-charge-Controller-Cheap-Tracer2210CN-/302292215470?hash=item46620526ae:g:jIQAAOSwU8hY8fWj

Edited by reg
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Not sure why you'd want a higher voltage tbh. It can handle a 60 cell domestic panel no problem and a 250W panel would top out at a bit below 20A. If you wanted to hook up another panel you'd just put them in parallel. 

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22 minutes ago, Jambo said:

Not sure why you'd want a higher voltage tbh. It can handle a 60 cell domestic panel no problem and a 250W panel would top out at a bit below 20A. If you wanted to hook up another panel you'd just put them in parallel. 

The reason why a higher input voltage is desirable is because the trend over the last few years has been to produce higher voltage and lower amperage panels this trend has come about because of the ability of mppt controllers to handle the higher input voltages and the fact that the higher voltage panels will work better in low light situations. 

For example I am awaiting delivery of 2 175w panels with 30voc and 8.25a

I intend to wire these to give 60voc and 8.25a. As the light drops the voltage drops but a charging voltage should be available under low light conditions, a good mppt controller will then raise the charging current. If I wired it as 30voc and 16.5a then the point at which a charging current is no longer available, due to low light conditions, will come sooner than on the first example. 

Basically I should be getting some charge in low light conditions with the 60v configuration whereas the 30v configuration may have dropped below a charging voltage. As you may have deduced yourself this is particularly useful in winter low light conditions where, given the same conditions,  some charging could take place instead of zero charging taking place. 

Thisis where the beauty of the mppt controler technology scores

 

 

 

 

 

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1 minute ago, reg said:

The reason why a higher input voltage is desirable is because the trend over the last few years has been to produce higher voltage and lower amperage panels this trend has come about because of the ability of mppt controllers to handle the higher input voltages and the fact that the higher voltage panels will work better in low light situations. 

For example I am awaiting delivery of 2 175w panels with 30voc and 8.25a

I intend to wire these to give 60voc and 8.25a. As the light drops the voltage drops but a charging voltage should be available under low light conditions, a good mppt controller will then raise the charging current. If I wired it as 30voc and 16.5a then the point at which a charging current is no longer available, due to low light conditions, will come sooner than on the first example. 

Basically I should be getting some charge in low light conditions with the 60v configuration whereas the 30v configuration may have dropped below a charging voltage. As you may have deduced yourself this is particularly useful in winter low light conditions where, given the same conditions,  some charging could take place instead of zero charging taking place. 

Thisis where the beauty of the mppt controler technology scores

 

 

 

 

 

Higher voltage also means smaller, and hence cheaper cable runs. 

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Perfectly happy with my 30A Tracer Bn 3215 which according to Bimble are made by the same factory who make the Outback. Currently £145 from Bimble, I have 2 (& 4 165W panels)
http://www.bimblesolar.com/offgrid/mppt/Tracer3215BN

2 panels wired in series into 1 controller, & then the same again.

Link to panels showing their spec - http://www.ebay.co.uk/itm/301063511827

If price is an issue you can always start small say with just 2 panels & 1 controller, & then later add 2 more of the same with a 2nd controller. Like I said I have 4 of these panels on a 58' boat. I could fit 2 more, but then I'd have nowhere to put my coal & wood.

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4 minutes ago, Ssscrudddy said:

Perfectly happy with my 30A Tracer Bn 3215 which according to Bimble are made by the same factory who make the Outback

I have mentioned it before, but it looks identical to the Outback models.

I'm thinking of getting a couple of the 40A ones. The one I currently have has a noisy fan in it. 

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Wiring in series leads to shading issues though. I guess there might be a benefit to the higher voltage from series wiring in winter if you have a clear view of the sun but you're getting so little in winter anyway does it make a significant difference? 

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13 hours ago, Jambo said:

Wiring in series leads to shading issues though. I guess there might be a benefit to the higher voltage from series wiring in winter if you have a clear view of the sun but you're getting so little in winter anyway does it make a significant difference? 

The difference is that you get some charging in winter albeit an amp or 2 rather than no charge. IMHO Some is better than none. 

Having said that every set it has to take account of individual requirements e.g I have two unisolar stick on panels one on each side of a curved roof, initially I had them wired together through one controller but low angled light, typical in winter,  would drag both sides down. I have now separated these and each has its own tracer BN 10a controler. 

My new pair of additional panels will be flat and are only required for low light conditions so the high volt low amp set up is the ideal for this case. 

I do have another flat mounted 240w panel through a Tracer BN 20a controler so these together with the unisolar panels give me more than enough in summer. 

As I say it's all down to individual circumstances and configurations

 

 

 

 

 

 

Edited by reg
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