MPPT Solar Controllers?

I was speaking to a chap from this company who recommended a Victron 75/15 for me 2 x 120W panels in series.

http://www.windandsun.co.uk/product...lers-/Victron-Charge-Controllers#.Vq91DfFy5iY

Anyway the controller is rated at 200W so he said that on the rare occasion you get more than 200W then you'd get clipping but he said you'd so rarely see more than 200W of power that it would be a waste getting a bigger controller.

Does that sound like good advice or will I benefit from that extra 40W sufficiently frequently to be getting a bigger controller?
 
northcave said:
Ok so was going to wire my new panels in parallel and update the wiring but after some consideration I might wire them in series and buy an MPPT controller to replace my standard on (which I will use elsewhere). Hence keep the amps the same and not needing to upgrade existing solar cable.

Anyway, people always warn of watching out for some MPPT being rubbish and not actually MPPT. On eBay there are tonnes of them all claiming to be fully MPPT. Can anyone recommend a model and / or if these £40 ones in eBay are what they say they are?
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Ah - I was just penning a reply to your other post - I was concerned that your 16amp PWM controller would be operating at its limit - which I don't think is a good idea. Perhaps you could go to a 30 amp (Steco - £45 on ebay) - it has all the digital displays to let you know what is coming from the panels to what is actually going into the batteries. Alternatively, wiring in series you could go to an MMPT controller (much more expensive). But do have a decent margin in the spec - you may want to add another panel. Also make sure the wiring is a good size. I saw a Norwegian yacht in Leros that had doubled its panels size but not the wiring - go up in flames.

I get 8 - 9 amps between 11 and 4 from my 2 x 85 watt panels. I would increase it to 10 with an MMPT controller probably.

Question: Which wiring method would be best to reduce the loss of power due to a shadow on one panel.
 
North cave: looking at the link I see the blurb specifies 75V input for that regulator. The 100/15 model specifies 100V. I'm very far from being a sparks but most good MPPT controller specify any input voltage up to a certain maximum (which is often as high as 150V). Why do Victron describe their controllers in this way, particularly as the bloke from Wind & Sun evidently said you could ignore the voltage and use it for two-panel a set-up with around a nominal 40V. I'm puzzled and would value an opinion (as I daresay would the OP), from anyone more knowledgable.

That's one part of my response, related to the other: In your particular situation I'd think carefully about splashing out on kit which doesn't have a degree of future-proofing. What happens if you decide to add another 120W panel? To some degree this harks back to my comments on a previous related thread, where you seemed not to grasp the cabling latitude that an elevated voltage/MPPT set-up can offer. I appreciate that you're going to considerable lengths to try to get the best guess as to your power needs, but until you're actually out there, that's all it can be: a guess.

Good luck.
 
macd said:
That's one part of my response, related to the other: In your particular situation I'd think carefully about splashing out on kit which doesn't have a degree of future-proofing.
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Thanks. Yes I was considering future proofing with a larger controller but it could be limited.

For example assuming i run these latest 2 x 120W panels in series then any additional panels in the future will have to go in series would could cause an issue if they are on a different place on the boat. I.e. A series setup will only run as god as the least performing cell. That has fail all over it.

I could then rig them in parallel but arguably I don't need an MPP controller then and I'm unsure of the consequences of putting multiple solar panels into one regulator, potentially of differing powers, which are located on different parts of the boat.

My conclusion is that one big high capacity controller is not a good one. I'd be best having a separate controller for each array as such. I.e. one for the two on the goal posts and another for those on the coach roof for example.
 
I'm following various solar panel discussions with interest since I decided to fit a couple of probably 150-180W panels instead of a bimini on my motorboat.

Question is slightly different to what I'm seeing here:

do I need split charger diodes or just chuck everything in the battery bank?
Currently have port engine alternator charging the service bank (2X2X12V/180Ah lead acid batteries), a generator/shore power charging said bank through a Victron intelligent charger and now probably an MPPT pumping more current to the system.
Boat is in the Med, panels are unobstructed so hopefully get enough current in.

How do I deal with various sources running concurrently? Ignore them and assume they work, or what?

cheers

V.
 
vas said:
I'm following various solar panel discussions with interest since I decided to fit a couple of probably 150-180W panels instead of a bimini on my motorboat.

Question is slightly different to what I'm seeing here:

do I need split charger diodes or just chuck everything in the battery bank?
Currently have port engine alternator charging the service bank (2X2X12V/180Ah lead acid batteries), a generator/shore power charging said bank through a Victron intelligent charger and now probably an MPPT pumping more current to the system.
Boat is in the Med, panels are unobstructed so hopefully get enough current in.

How do I deal with various sources running concurrently? Ignore them and assume they work, or what?

cheers

V.
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A diode splitter is for splitting the charging between two different batteries or battery banks. Between an engine start battery and a domestic services battery bank for example.

It is not a device for combining the outputs of two or more charging devices to charge one battery or battery bank. . You would just connect them in parallel with each other. The battery will take what it needs but it wont necessarily be drawn equally from all sources.
 
VicS said:
A diode splitter is for splitting the charging between two different batteries or battery banks. Between an engine start battery and a domestic services battery bank for example.

It is not a device for combining the outputs of two or more charging devices to charge one battery or battery bank. . You would just connect them in parallel with each other. The battery will take what it needs but it wont necessarily be drawn equally from all sources.
Click to expand...

doh!
been a long day, thanks VicS.

I have a split charge diode lying around after clearing up the electrics during the rebuilt, but looks like it'll remain unused (unless I decide to use it to split the solar panel output into charging both service and engine bank...)

cheers

V.
 
vas said:
doh!
been a long day, thanks VicS.

I have a split charge diode lying around after clearing up the electrics during the rebuilt, but looks like it'll remain unused (unless I decide to use it to split the solar panel output into charging both service and engine bank...)

cheers

V.
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dont forget diodes drop about 0,7 volt.

If there are other charging devices in use a controller with two outputs may be a better choice
 
northcave said:
1. A series setup will only run as god as the least performing cell. That has fail all over it.

2. I could then rig them in parallel but arguably I don't need an MPP controller then and I'm unsure of the consequences of putting multiple solar panels into one regulator, potentially of differing powers, which are located on different parts of the boat.
My conclusion is that one big high capacity controller is not a good one. I'd be best having a separate controller for each array as such. I.e. one for the two on the goal posts and another for those on the coach roof for example.
Click to expand...

1. As said, I'm no expert and wiser heads might say otherwise. However, I believe it's quite wrong that panels run only as well as the least performing cell...any more than a battery of five good cells and one failed cell runs in the same way. And I can assure you that my series panels absolutely do not behave in that manner.

2. Yes, plenty of boats run satisfacoriy with more than one controller, and I've done it myself. However, there is an issue that the performance of two 'smart' controllers will interfere with each other towards full charge. I'd put it no more strongly than that.
 
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Chris_Robb said:
I would not bother charging the engine battery especially with a splitting diode.
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my thoughts as well, there's NOTHING connected on the engine batteries, they don't drop even after 3months uncharged but connected which cannot be said for the service batteries.
So yes, will just connect and charge the service ones only and leave the splitting diode where it belongs (shelf in the garage...)

Now the point is to find the right (size and pricewise) panels

cheers

V.
 
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