@plonkster, @Jaco de Jongh

How is this looking for a change in equipment?

I know the battery bank is smaller, but the rest seems pretty decent

 

Is it possible to move this thread to the solar energy section instead of showcase?

8 minutes ago, stoic said:

How is this looking for a change in equipment?

Well now you're playing in a different price class, so certainly no complaint in that dept! :-)

Why not Multiplus-II? The quiescent draw on those units are significantly less on the Multiplus-II, and the price should be a little lower too (Current Automation were selling them around 12.5k a while ago).

Do you have space for 24 panels? You're going to need a good 50 square meters to fit them (plus some service space between them). Also that is almost 8Kwp of PV, at roughly 50V that's 160 amps, but you only have MPPTs for a little over half of that. Unless you're planning on oversizing, but 60% oversizing is a bit much. You should probably look at 150/60 controllers, or at least 2 x 150/70 if you want to go for 140A with a bit of oversizing.

The voltage also has to be kept in mind. For the 150V controllers, you can only put 3 modules in series, so you will have to make 8 strings of 3 panels each. Each string will push up to 9A, so that's around 35A per controller on the PV side (if you use two controllers) or 25A if you use three controllers. If you go for the 250V controllers, then you can series up to 5 panels (so you'd go for either 20 modules or 25 modules total), then you could probably go with 2 x 250/100 controllers, 5 strings of 5 panels each, and your cabling becomes simpler and less expensive, but the MPPTs cost more.

You are also (as you admit) a little bit underbatteried. With 8Kwp of PV, and the Pylons really want to charge at C/2, you need 16kwh, 4 times more than you have now, although I'd say you want to go with at least 4 battery modules if possible.

I think if I were you I'd put up less PV and spend a bit more on batteries at this point, and then later expand with more PV.

 

23 minutes ago, plonkster said:

You are also (as you admit) a little bit underbatteried. With 8Kwp of PV, and the Pylons really want to charge at C/2, you need 16kwh, 4 times more than you have now, although I'd say you want to go with at least 4 battery modules if possible.

I think if I were you I'd put up less PV and spend a bit more on batteries at this point, and then later expand with more PV.

12 panels, 3 batteries? 

I'd like to stay in his price range in order to have at least 16k for rails and connectors and so fouth

4 minutes ago, stoic said:

12 panels, 3 batteries? 

Yup, that was my idea as well, though I didn't do the math. 4KWp o f PV, that's 80A, and 3 Pylontech modules wants 75A charging. So this is spot on, perfectly matched.

Now you can also look at 2 x 150/45 controllers, 4 strings of 3 panels each, two strings on the one controller and two on the other. The 150/45 controller is hardware wise a bit newer and more advanced than the 150/35.

And see if you can use the Multiplus-II inverter, as I said, I saw better prices for that one. You can save a good 10k if I'm right (though of course I may not be... exchange rates change... stock gets sold out).

 

 

3 minutes ago, plonkster said:

And see if you can use the Multiplus-II inverter, as I said, I saw better prices for that one. You can save a good 10k if I'm right (though of course I may not be... exchange rates change... stock gets sold out).

Just placed requested a quote for the 3 multiplus II's, they will only have stock in jan ... but it is a 9k saving so it is worth the wait

3 hours ago, plonkster said:

2 x 150/45

Why not Smart Solar 250/100. Allowing for 4 series and 3 parallel  for now and 1.8kw expansion for future use. And basically latest on the market if i am not mistaken.  

150/45 allow for 2600 watt panels (In future you can add 3 panels to each controller and oversize the array by 14.2% on each controller)

250/100 allow for 5800 watt panels (in the future you can add 8 panels to the controller and oversize the array by 13.8%)

2x 150/45 + less than 1k = 250/100. 

3 hours ago, stoic said:

Is it possible to move this thread to the solar energy section instead of showcase?

Done.

1 hour ago, Jaco de Jongh said:

Why not Smart Solar 250/100

I second this, but for the reason that 3 panels in series comes a bit too close to exceeding the 150V limit. 

Prior to installation, and on the ground quick test of panels we measured over 50V on a 72 cell. (Granted not a calibrated meter).

Plenty of headroom for a 4 panel string on the 250V capable version.

 

Just now, phil.g00 said:

Prior to installation, and on the ground quick test of panels we measured over 50V on a 72 cell. (Granted not a calibrated meter).

Oookay. Cause I have a 3-module string on a 150/35. I've never seen more than 135V. I suppose it might depend on the kind of panel as well. @The Terrible Triplett, what's that spreadsheet tool you use again? I should probably know... I just don't :-)

2 minutes ago, plonkster said:

what's that spreadsheet tool you use again?

That'll be this one found here

Had it because I'm busy with it at the moment 😂

Yes, very panel dependent, very temperature dependent and very reliant on manufacturer spec and having no variation.

From what I read on other MPPT literature it is a very hard 150V limit, no leeway.

There may also slight variations in the withstand capability of these MPPT components too. Bear in mind the panels are there for 25 years.

I don't like to be reliant on a 3V safety margin for that length of time.

Incidentally, the panels I measured exceeded their stated Voc, which was around 48 voltsish. Probably would've passed the spreadsheet test.

 

Edited December 12, 20187 yr by phil.g00

27 minutes ago, phil.g00 said:

I don't like to be reliant on a 3V safety margin for that length of time.

Me neither, but I am okay with 15V (that's like a whole 10% :-) )

This from the Outback MPPT manual:

 

49 minutes ago, phil.g00 said:

This from the Outback MPPT manual:

That's like -20°C. I don't think Sutherland manages that most years :-)

1 hour ago, plonkster said:

... spreadsheet tool ...

At the risk of repeating myself ... when you play with 12/24v, you are pushing the limits.

In the words of Victron SA: If in Africa, do not oversize, even if the VE-MPPT-Calc allows that.

I pushed the calcs, big panels, small controllers, all allowed. Yet my query went all over Victron Europe, back to Victron SA ending at a very experienced dealer that explained to me in terms I understood as by then I had found the problem, so I could relate to "why not", and not just "Don't".

It boils down to that in i.e. Europe, colder climate and shorter sun hours, you can oversize yes ... wisely.
But when in Africa, just don't.

The problem comes in not with the volts, as one is wise. It has everything to do with the heat the controller is going to have to deal with.

On my previous 150/35, AND the new 150/100, I had to put a fan on them both. You cannot hold your hand on them for more than a few seconds, running at full tilt in an ambient temp of +-30deg Celsius.

Yes, the 150/35 and 150/100 CAN handle the temp yes, but at the heat they are generating, it is not good for the lifespan of the controller.

But it is each and everyone's call, me, I'm putting a fan on them now, as they are working flat out. 

On the volts, see below my config, the installer disagreed with that and he was right. Have not seen anything above 135.4v max. But the HEAT ... it is serious.

Edited December 12, 20187 yr by Guest

Outback are a global brand, I think the stipulation is for the Canadianese.

I just wanted to illustrate the point that a there is fairly large voltage swing with temperature.

If a 25V safety margin is recommended at -20°C, some proportional safety factor applies if you get frost/snow in your area. 

2 minutes ago, phil.g00 said:

I just wanted to illustrate the point that a there is fairly large voltage swing with temperature.

And I concur. Outback, Monrnigstar, Victron ... all have warnings about the temp, and each panel manufacturer has their own values. Be wise.

My case, what got Victron's attention very quick was when I sent them this, asking, IS this really "Accepted"?

Edited December 12, 20187 yr by Guest

@The Terrible TriplettThat's exactly my point, it is cutting it too fine, hence my recommendation for a 4 panel string on a 250V MPPT.

Edited December 12, 20187 yr by phil.g00

4 hours ago, Jaco de Jongh said:

Why not Smart Solar 250/100. Allowing for 4 series and 3 parallel  for now and 1.8kw expansion for future use. And basically latest on the market if i am not mistaken.  

150/45 allow for 2600 watt panels (In future you can add 3 panels to each controller and oversize the array by 14.2% on each controller)

250/100 allow for 5800 watt panels (in the future you can add 8 panels to the controller and oversize the array by 13.8%)

2x 150/45 + less than 1k = 250/100. 

I did not know that i can get by with one mppt on the three inverters in parralel.

But this works out more orr less the same as three of the ones i wanted. @plonkster is it possible to tun one charge controller one three multiplus-II inverters for three phase power?

 

Edited December 12, 20187 yr by stoic

10 minutes ago, phil.g00 said:

@The Terrible TriplettThat's exactly my point, it is cutting too fine, hence my recommendation for a 4 panel string on a 250V MPPT.

We agree ... but see the first pic ... CoCT does not go below 10 degrees on a full blast sunny day. :-) 

So it is a gamble, as I don't want to drop it to 100v if I go 2 in series and 3 in parallel. 

EDIT: But I will if I see the volts touching 148v on sparkling day.

Edited December 12, 20187 yr by Guest
Added T&C's

Unfortunately, a bit further inland we are not so blessed.

3 hours ago, stoic said:

I did not know that i can get by with one mppt on the three inverters in parralel.

Hi Stoic, please remember, the charge controller connects to the "battery" in principle, not the inverter. you will share the battery bank between the three, so actually they "don't know" what charges the battery, as long as it is charged for them to use.  

24 minutes ago, stoic said:

... is it possible to tun one charge controller one three multiplus-II inverters for three phase power?

Yes you can. DC side versus AC side, the two are mutually exclusive.

 

Titbit. Morningstar was the first manufacturer to say you can add more than one of their controllers onto the same battery bank PROVIDED the two controllers are identically programmed. First they said identical models, but that was changed later. 

Today it is commonly used, became a fine art, like East/West facing arrays and all that ... 

I pushed that envelope. Had various MPPT's, all programmable, on the same battery bank for years, set identically because of a 400w and a 930w array. At times I got the full potential out of both arrays, IF the inverter required that. 

 

Edited December 12, 20187 yr by Guest

1 hour ago, The Terrible Triplett said:

The problem comes in not with the volts, as one is wise. It has everything to do with the heat the controller is going to have to deal with.

Honestly, I still think too much is made of this. These devices are rated at 40°C (as opposed to 25°C that is often used for inverters), and they derate further as they get hot. If they overheat they protect themselves and stop charging. Hand-burning temperatures should be around 60°C, if I judge from my experience with CPU chips (at 85°C you start talking blisters). And honesty... that is not that much.

Sure... it might not last a decade, but it should last the 5 years of warranty :-)