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17 hours ago, Solaris said:

SUP... 

Tell us, what brings you to our world?

Solar panel newb here. Want to dive in and setup some test beds then eventually work things up to a larger scale.

Looking at buying in some panels soon so been looking at whats available online in SA.

Looks like the JA 405W, the Canadian Solar 410W, the Trina 405W Mono "Tallmax M" panels are about as big as we have here right now.

Some things I am wondering about. The VOC. From what I have understood this is really only an issue in certain conditions...such as early morning when its cool with clear sky conditions and bright morning sun. What I am wondering is in the area I am in where its very very hot all the time (never below about 25 C and usually in the low to mid 30's) if realistically I will ever hit that VOC from a panel ?

Trying to figure out how many panels I can safely put in a string for a given Mppt controller. Many of the newer inverters have Mppt onboard so lots to consider when selecting components for a new system from scratch.

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I also remember when solar panels were $900 ea! and batteries were cheap.....but then again racing was dangerous and sex was safe.. back then.

Now racing is a safe past time, sex is dangerous, panels are cheap and we need to sell a kidney to have batteries. Ahhh, progress..... you gotta love it.

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8 minutes ago, Stanley said:

Yep, when I started in this industry I remember solar panels were around R50/Watt

Now they are less than 1/10th of that, and the currency is worth much less so the actual price is much lower.

So Stanley, if you have been around that long then you most likely know a thing or two about solar panels. Will we ever hit a panels VOC in really hot parts of SA?

Edited by Delta9
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What is the highest wattage panel in SA at this time? Seems to be the 410W Canadian Solar from what I can see. Is Canadian Solar a good brand? The Trina Tallmax panel is 19.9% efficient. I would prefer to get the most efficient high wattage panels I can. What panel is favored by most here ? Is there any particular panel to avoid like the plague?

 

 Lots of questions I know. Still how else do we find these things out other then ask around from those who have already been down this road.

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VOC is the 'Open Circuit' voltage. Which means the voltage the panels produce when no current is being drawn from them. Panels don't need a lot of irradiance to generate their VOC just that with little irradiance you won't get much current before the voltage collapses. VOC will usually be reached every morning when the sun hits the panels and the MPPT is still 'sleeping'. The only real concern is that VOC is temperature dependant, so you need to calculate (from the panels data sheet) what the expected VOC will be on the coldest days in your area.

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1 minute ago, Vassen said:

You also have to consider what they call the cloud edge effect. When you have a clear day and suddenly large cloud comes over and shades your panels, the panel then has some time to cool down a bit and when the cloud moves away again you have a spike in voltage. 
 

it’s best to have some tolerances available. With string inverters, you can connect a fair amount of wattage on the mppt. If you go the Victron route, then the series panels are not that many but you have lots of them in parallel. 

 Hadn't considered that. Good to know. Thanks.

I have a Victron Inverter with AGM's but no panels nor have ever had any hence not much of an idea about them. That seems to be the thing against Victron from what I can see. Their Mppt controllers are expensive and fairly low voltage forcing parallel strings which I dont like the idea of.

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8 minutes ago, Stanley said:

VOC is the 'Open Circuit' voltage. Which means the voltage the panels produce when no current is being drawn from them. Panels don't need a lot of irradiance to generate their VOC just that with little irradiance you won't get much current before the voltage collapses. VOC will usually be reached every morning when the sun hits the panels and the MPPT is still 'sleeping'. The only real concern is that VOC is temperature dependant, so you need to calculate (from the panels data sheet) what the expected VOC will be on the coldest days in your area.

Thanks Stanely. Appreciate the guidance. 

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I have a 5Kva Quattro that has served me well for 10 years this year. Heavy load shedding over those years and on my second AGM bank. Cant complain, its all worked very well. Cant imagine life without it, the grid being what it is these days. I have used the Grid as the charging source for the batteries and the Quattro picks up the house load almost instantly when the grid goes down. 

However with the rising cost of energy and the uncertainty of just how far down things may go in the years ahead our thinking is to be energy self secure regardless of cost. Life is too short to let eskom dictate our lifestyle and when our life must go on hold because they cant manage things so well.

So this means panels are now mandatory. The Quattro is 10 years old. Its not giving any sign or hint of a problem but its probably not a bad idea to renew so the next 10 years are trouble free. 

So now to figure out the way forward.

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4 hours ago, Delta9 said:

However with the rising cost of energy and the uncertainty of just how far down things may go in the years ahead our thinking is to be energy self secure regardless of cost. Life is too short to let eskom dictate our lifestyle and when our life must go on hold because they cant manage things so well.

This is the exact same mindset I have. I don’t want my life dictated by when Eksdom decides to turn off or on. Life must go on regardless. I always see people talking about “return on investment” and I shake my head. It is not about how much you could save, it’s about life not being interrupted. Unfortunately we have all become far too dependent on government, let us now gain independence!  (Anyone reading this, please feel free to disagree) 

 

 

Another point to keep in mind.... I see you want to install the biggest panels available. If you, like me, do the installations yourself, keep in mind that a 72 cell panel measuring roughly 2m by 1m can get a little heavy. This is especially true when you live in a windy area like I do. When you are trying to mount panels on a roof and the wind comes up, that panel acts like a sail. It can be most frustrating when you get blown all over the roof trying to commandeer a 21kg panel that is catching wind like a kite. 🤬🤬🤬 It is easier to mount a smaller panel or alternatively get some help from a friend. 

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Loads of questions. Apologies in advance.

If I have a 5Kva Quattro and add another to each phase so that I have a 3 phase Quattro setup...is that a 3 Phase 5Kva setup or a 3 phase 15Kva setup?

Early days on this but the thinking on this is the original Quattro is 10 years old and we wonder what the actual life span of a quality Inverter actually is. If we bought 2 new 5Kva Quattro's and put one on each phase (of course would have to re-wire the DB to balance the loads) then when the original old Quattro lets go one day in the future there are still 2 phases UP for us to use ...its sort of a back up plan for inverters keeling over and dying on us (because you just know the inverter is going to die at 10PM on a Saturday night during a wild storm lashing the area in the middle of a very prolonged load shedding incident - and still have 2 phases up going strong...its a comforting thought).

If one were to opt for a single 3 phase inverter (that is one box with all 3 phases on the one inverter box) and that inverter dies, then its light out. More expensive to go for 3 single phase inverters all joined together, but as the saying goes....2 is 1 , 1 is none (or in this case 3 is 1, 1 is none ??)

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