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Are there any 300V input (or higher) MPPT charge controllers available in SA?


tetrasection
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As the title says. Thinking of getting some more panels but it would be too much power for my Outback FM60 to handle. If I'm gonna upgrade then I would like to rewire my 3 parallel strings into one series string of 9 panels which comes up to around 260V at 8.1A and then add the equivalent Voltage (7 panels) worth of new 8.9A panels into a second series string.

So far this is the best alternative I've seen https://solarpanelenergy.co.za/p/958306/5kw-growatt-spf-5000-es-inverter but I'd much rather spend less on just the MPPT if they do actually exist, since I already have an inverter.

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19 minutes ago, tetrasection said:

As the title says. Thinking of getting some more panels but it would be too much power for my Outback FM60 to handle. If I'm gonna upgrade then I would like to rewire my 3 parallel strings into one series string of 9 panels which comes up to around 260V at 8.1A and then add the equivalent Voltage (7 panels) worth of new 8.9A panels into a second series string.

Yes there is a 600V MMPT that is hellish expensive, if you kept your max Voc of your string below 250V you would have many more options.

That answers your question.

It doesn't address the options available to you though.

1.) Is your Outback maxed out? - I don't mean on paper, I mean what is it's actual peak current? I have often found 30% headroom difference from theory and practice. 

2.) If it is, why not get another and keep it, MPPT's can be paralleled on the battery side. I have 4 Outbacks in parallel.

 

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48 minutes ago, Stanley said:

The MLT Inverters', Nomad charge controller has a maximum Voc of 375V

https://www.mltinverters.com/documents/nomad_manual.pdf

(In the manual it says the maximum input is 400V, but that just means it won't blow up at 400V. It will refuse to operate if the input is above 375V)

 

I saw that one, but it's like 18k rand... Growatt hybrid inverter is only 13k.

 

36 minutes ago, phil.g00 said:

Yes there is a 600V MMPT that is hellish expensive, if you kept your max Voc of your string below 250V you would have many more options.

That answers your question.

It doesn't address the options available to you though.

1.) Is your Outback maxed out? - I don't mean on paper, I mean what is it's actual peak current? I have often found 30% headroom difference from theory and practice. 

2.) If it is, why not get another and keep it, MPPT's can be paralleled on the battery side. I have 4 Outbacks in parallel.

 

I'm only utilizing around 25A so I have room where amps are concerned. Problem is I have 6x 29V panels (8.2A) and 3x 31V panels (8.1A) at the moment, set up in 3 strings of 2x 29V + 1x 31V.

The new panels I wanna get give 8.9A at 37V so adding more strings isn't really possible without loosing a lot of performance due to the mismatch.

Buying a second Outback might work... Though that would set me back around 12k, and around 3k for cabling (the panels are like 60 meters away from the batteries). Also, I wouldn't be able to sell my existing Outback to make up some of the expense. So it looks like that would also be more a pricey option compared to the Growatt hybrid inverter (which would replace both my Outback and my inverter, opening them up for resale).

 

Edited by tetrasection
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5 minutes ago, tetrasection said:

I'm only utilizing around 25A so I have room where amps are concerned. Problem is I have 6x 29V panels (8.2A) and 3x 31V panels (8.1A) at the moment, set up in 3 strings of 2x 29V + 1x 31V.

Just checking, these voltages are open circuit voltages (Voc) and not Vmp ( maximum power voltage)?

What is your DC battery voltage?

What are the panel dimensions?

Edited by phil.g00
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17 minutes ago, phil.g00 said:

Just checking, these voltages are open circuit voltages (Voc) and not Vmp ( maximum power voltage)?

What is your DC battery voltage?

What are the panel dimensions?

That's Vmpp.

I'm running a 48V system, 2 strings of 4x 200AH gels.

I have 6 of these 235W panels https://www.skyfireenergy.com/wp-content/uploads/2011/04/DS_Sovello_Project_Pro_P_V1.2.pdf.

Model number is the same but for some reason mine say 29V and 8.2A on the sticker but the PDF says 8A at 29.4V... maybe there are regional variants?

The other 3 panels (8.1 Impp, 31 Vmpp) are 250W "Sky-King" or something chinese.

The panels I'm thinking of getting are these 330W ones https://mcusercontent.com/1547c2fe7c9a7a2586f3e482b/files/75e7cc1d-8982-4f7e-a63f-b7e3d5420b1b/BYD_P6C_36_5BB_EN.pdf

Edited by tetrasection
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OK, an MPPT voltage rating is a hard limit, based on open circuit voltages. Not only that it is such a hard limit that you have to factor the temperature coefficient of your coldest day on the Voc.

Those panels have a Voc of 37.1V at 25C and a temperature coefficent of -.34%/deg

So if your lowest teperature was say -5C, then the Voc would be 37.1V + 30C x ( .0034 x 37.1) = 40.9V

An outback has a 150V limit, so the maximum panels in series would be 3 ( 3x 40.9 = 123V, which is less than 150V, so you're OK).

So you can easily do 3 parallel strings of 3 in series of your existing panels and unless your panels are perfectly aligned, I bet you don't even peak at 20amps.

So really you want to replace the Outback with a much cheaper 150V/20A or 150V/30A MPPT and reuse it for your more powerful panels.

(There are many options in this range, the MPPT's dont have to be the same brand, just the same settings).

Next thing, unless you really have to, don't buy an odd number of panels, and if you really have to buy an odd number, don't buy a prime number of panels.

These new panels will probably have a Voc of too close to 50V for comfort ( unless you live at the coast), so for the outback you'll need 2 panels in series strings, but you could easily 4 strings of 2 in series, probably up to 8 strings or so. 

All the strings don't have to face the same way if you have future expansion plans.

 

Edited by phil.g00
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Sorry I just want to correct my MPPT selection above.

I would estimate your existing peak of your 235W panels at probably 200W ( unless they are perfectly aligned and spotlessly clean).

So about a 1800W peak for 9 panels..

A 48V system probably charges around 53V ish, so 1800/53V = 34A, so a 150/35A MPPt is what you are looking for to free up your Outback.

(The Outback history data will be more reliable).

Edited by phil.g00
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5 minutes ago, phil.g00 said:

Sorry I just want to correct my MPPT selection above.

I would estimate your existing peak of your 235W panels at probably 200W ( unless they are perfectly aligned and spotlessly clean).

So about a 1800W peak for 9 panels..

A 48V system probably charges around 53V ish, so 1800/53V = 34A, so a 150/35A MPPt is what you are looking for to free up your Outback.

 

Awesome idea! Thanks for the advice! I do pull in over 2100W quite regularly, peak according to the outback's lifetime history is almost 2400W!

Edited by tetrasection
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I wouldn't size for 2400W, that will be a freak occurrence, but lets say 2200W.

Then 2200/53 = 41Amps, (It is is OK to exceed the output current limit), so a 40A MPPT will do. (The charging voltage is probably closer to 55V anyway).
 

One thing that will cost extra is you will need several wire runs to avoid the losses over that distance.

You may want to consider 60 cell panels that will allow you to put 3 in series and benefit from the higher voltage.

 

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12 minutes ago, phil.g00 said:

Then 2200/53 = 41Amps, (It is is OK to exceed the output current limit), so a 40A MPPT will do. (The charging voltage is probably closer to 55V anyway).

On the other hand, you are now into a size where you can keep your Outback where it is and size the MPPT just for the new panels if you go for either 6,8 or 9 panels.

( Depending on 72 or 60 cell variants).

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1 hour ago, phil.g00 said:

On the other hand, you are now into a size where you can keep your Outback where it is and size the MPPT just for the new panels if you go for either 6,8 or 9 panels.

( Depending on 72 or 60 cell variants).

 

Now we're back on the search for a high voltage MPPT that's cheaper than the Growatt hybrid inverter 😅

Or go with many parallel strings and find a "normal" voltage MPPT that works out cheaper after factoring in the cable run...

Edited by tetrasection
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Do have an inverter/charger or just an inverter?

Or alternatively, can you use a PV inverter (PV straight to AC), but it only works when there is a grid supply.

By that I mean only reduces the bill, it doesn't work when there is load-shedding.

PV inverters are relatively cheap and have very high voltage MPPT's built in.

 

 

 

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11 minutes ago, tetrasection said:

Think I'm just gonna go with that Growatt inverter... Will be a nice bump from 3kw to 5kw, will save me the hassle of wiring a new setup for high amps, will take care of the existing voltage drop and I can sell my inverter and charge controller to make up some cash...

 

I agree, in your instance it would seem the most attractive option.

Although the MLT has 2 MPPT's, the Growatt only one?

Edited by phil.g00
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I was planning on making 2 parallel strings.

Re-connect the 9 existing 8.1A panels in series (which comes to 266Vmpp) and then mount another string with 7 new 8.9A panels in series (comes to 260Vmpp).

So I'll end up with 8.1A + 8.9A = 17A @ 260V (power loss of 49 watts from the 6 volt mismatch).

Edited by tetrasection
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