43 minutes ago, viper_za said:

But now say you have three 72-cell panels in series and one panel gets shaded.

Also then how would one tell if the diodes couldn't prevent damage.
Can you by looking at the cells see physical damage?
Then will the non shaded ones show the damage or the shaded ones?

Sorry @plonkster using you as an encyclopedia

It's more a question of having 6 72-cell modules in two strings of 3 each. So what you really have is 216 cells in each string. Now shade a fraction of the second string. That's when the potential for trouble arises.

I have no idea what happens. Never tried it. I think in the worst cases you get fire, but in the more generic case it just stops working with no real visible indication.

Put a Zener diode (of less than 9V) on a 9V battery for example. A Zener is designed to break down (and not die), but the idea is the same. Put too much current through there and that thing will desolder itself it gets so hot. When it dies, it's often not even visible. I had a Zener fail on my in my Microcare Charge Controller and you could not see it visibly, you could only see it was shorted when you measured it. I expect the same thing will happen with a solar cell.

A solar cell is essentially a diode, and behaves in the same way. If you put it in circuit and bias it with enough voltage, it conducts like any diode. Sure enough, if you shine some light on it it sommer biases itself forward and push out some power... which is the ideal, but in the dark at least they behave like diodes. If you put it in reverse, it breaks down if you go high enough. I expect it will fail in the same manner.

30 minutes ago, HeinTheTerrible said:

Everything is on Pre-Order  

Jip, they send a email out that the $/R exhange rate is causing a huge dilemma ... Dankie Z'Inc!!!

Just replace the fuse, you have the right holders.

21 minutes ago, plonkster said:

A solar cell is essentially a diode, and behaves in the same way.

I can confirm to that. No fire but panel did heat up at the one spot in the junction box and literally de-soldered a diode ... replaced the diode and the panel is working again.

27 minutes ago, plonkster said:

It's more a question of having 6 72-cell modules in two strings of 3 each. So what you really have is 216 cells in each string. Now shade a fraction of the second string. That's when the potential for trouble arises.

Thanks Plonkster.
Would you suggest putting diodes in with parallel strings like mine? (I do get shade on them in the mornings)
If yes what should I be looking at?

1 hour ago, HeinTheTerrible said:

So you guys recon a 16A DC circuit breaker is too big for a single panel too? Can anyone send me a link to a online shop that sells the correct size fuse or circuit breakers?

Go to Rubicon in Reith Rd and speak to Ryno or Wesley. A 10A DC breaker should do. Rubicon have DC breakers, fuses and fuse holders. They may even have the inline MC4 fuse holders which will make the installation a doddle.

3 minutes ago, viper_za said:

Would you suggest putting diodes in with parallel strings like mine?

It has diodes already. Just put in the fuses (if you don't have them already) so that a reverse breakdown blows a fuse instead of a panel :-)

4 minutes ago, plonkster said:

It has diodes already. Just put in the fuses (if you don't have them already) so that a reverse breakdown blows a fuse instead of a panel :-)

Got the fuse

17 hours ago, HeinTheTerrible said:

Currently there are only two fuses for the 4 panels and each individual panel is supposed to be fused. 

I have two bussmann fuse holders at the moment.

Those are perfect, just add 2 more holders if you feel like it and use 12A fuses. If you want to work on the charge controllers etc. during the day and you need to disconnect the PV input, just open the fuseholders - no need to pull the fuses as well. At around 8A and a rather low voltage (+-40V) the tiny spark won't cause havoc if you open and close the fuseholders occasionally. If you do it a couple of times a day it is a different story though.

@The Terrible Triplett I got the data sheet on the batteries for you.

 

Not as good as I hoped it would be but it'll do for now.

Jip, I was worried for this.

To give you an example, Trojan T105RE batteries, at 20% DOD, gives you 4000 cycles.

At 50% DOD, if you want to go there, they give you 1600 cycles.

 

At the moment I've set the inverter to cut off/switch over at about 55% DOD.

This makes me sad

6 minutes ago, HeinTheTerrible said:

At the moment I've set the inverter to cut off/switch over at about 55% DOD.

This makes me sad

Jip, me too.

When people say they are wanting batts for solar and the batt people sell them maintenance free batteries, knowing full well they are NOT deep cycle with MAYBE a few hundred cycles versus a few hundred more per batt and they don't see you for many years ... they will sell you the maintenance free ones.

Sad thing for THEM is you will not return to buy more if you hit forums like this.

2 minutes ago, The Terrible Triplett said:

Jip, me too.

When people say they are wanting batts for solar and the batt people sell them maintenance free batteries, knowing full well they are NOT deep cycle with MAYBE a few hundred cycles versus a few hundred more per batt and they don't see you for many years ... they will sell you the maintenance free ones.

Sad thing for THEM is you will not return to buy more if you hit forums like this.

School fees hey  

5 minutes ago, HeinTheTerrible said:

School fees hey  

Yes, good point of view to take BUT the battery guys SHOULD not do it. 

After I had 3 sets of maintenance free batts, getting really gatvol of having to replace them, I met a crowd that sell batteries.

So when I met them, I asked the question, solar and what batts, wanting more of what I had? 

They refused to sell me anything bar Trojan for as they said, they will lose me for life if they sell me the wrong batt as the others did.

 

On 8/31/2016 at 2:42 PM, HeinTheTerrible said:

Currently there are only two fuses for the 4 panels and each individual panel is supposed to be fused. 

I have two bussmann fuse holders at the moment.

Got 4 of these babies with 12A fuses. Will install them over the coming weekend.

I might add 2 more panels soon, the 1kw array may not be enough come winter time. With the two extra panels Ill change to array from all in parallel to 2 panels in series that'll give me 3 sets. The new charge controller can handle 100v 60amp and the panels are 37v open curcuit so the best solution that my thick brain can come up with is the 3 sets of series panels. Btw, Ill change the fuses so each set of panels has a 20amp fuse.

Any input from the guru's?

39 minutes ago, The Terrible Triplett said:

Yes, good point of view to take BUT the battery guys SHOULD not do it. 

After I had 3 sets of maintenance free batts, getting really gatvol of having to replace them, I met a crowd that sell batteries.

So when I met them, I asked the question, solar and what batts, wanting more of what I had? 

They refused to sell me anything bar Trojan for as they said, they will lose me for life if they sell me the wrong batt as the others did.

 

My old toppie has a contact in the battery industry that deals with Trojan batteries. He bought a 48v 170Ah bank (T-875 model number) for his golf cart a couple of years ago at a very decent price. Next upgrade: Trojan batteries

I've connected mains supply to the inverter and changed some setting. 

When the batteries reach 23.5v the mains take over until the batteries are charged up again (via solar) to 24v or higher, then it switches back to the battery bank. Ill give this a try and see how it goes. This should extend the life of the batteries a little or am I missing something.

2 minutes ago, HeinTheTerrible said:

Ill give this a try and see how it goes.

Yes, you will be back. 

If you used SOC, using a BMV, you would be set, using volts to switch, naaaa, not working so well.

2 minutes ago, The Terrible Triplett said:

Yes, you will be back. 

If you used SOC, using a BMV, you would be set, using volts to switch, naaaa, not working so well.

Can anyone give me a small loan of a million rand so I can buy a full Solar edge system and just not worry

1 minute ago, HeinTheTerrible said:

Can anyone give me a small loan of a million rand so I can buy a full Solar edge system and just not worry

Cheques, in the post, or vouchers? 

Ask Camel for some awesome prices on BMV's, BEFORE you buy more batts, to make what you have last as long as you can.

Also Gumtree for 2nd hand BMV's if you can find one.

1 hour ago, The Terrible Triplett said:

Yes, good point of view to take BUT the battery guys SHOULD not do it. 

I think many of the battery guys simply don't know. They should, but they don't.

600 cycles to 50% is not bad for a weekend battery, or a UPS battery, or a second hand UPS battery that spent its whole life on float which you got hold off at a quarter of the price... but in all other instances, they work out close to R4/kwh...

On 8/31/2016 at 11:50 AM, HeinTheTerrible said:

My bad, its 8mm cable. Not 6mm.

 

Only two panels run in parallel to one charge controller, not all 4 panels on one pair of cable so the cable is thick enough according to my local supplier. 

where did you get 8mm solar cable?

11 hours ago, SilverNodashi said:

where did you get 8mm solar cable?

I was also a bit uncertain when I read his post, but then I googled and got many hits for 8mm² solar cable overseas, not sure if he actually have some of it or if he thinks it is 8mm². The popular sizes in SA are 4mm² and 6mm².

14 hours ago, HeinTheTerrible said:

Got 4 of these babies with 12A fuses. Will install them over the coming weekend.

Btw, Ill change the fuses so each set of panels has a 20amp fuse.

I assume you meant you'll change the fuses to 12A per set of panels?

1 hour ago, superdiy said:

I was also a bit uncertain when I read his post, but then I googled and got many hits for 8mm² solar cable overseas, not sure if he actually have some of it or if he thinks it is 8mm². The popular sizes in SA are 4mm² and 6mm².

Locally I can get 4mm, 6mm, 10mm and 16mm. Even 25mm if I ask nicely. So the 8mm might be imported? Might be cheap chinese knockoff solar cable as well.