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Which panels and from where?


Hagu13
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Time for some more panels.

I've got 6x315w Setsolar panels (72 cell) on my 5kVa Axpert. 3 strings of 2 for a voltage of around 60v which the Axpert manual says is optimal for my MPPT. About 5 years old.

It was enough when I was on gel batteries to go off grid in sunlight hours but now I'm on Pylontechs and I've got unused battery capacity that could get me through the night if I had the generation to fill them.

I can't get the same panels again and pretty much can't get 315w anything any more. So it going to be a mismatched system and I'm going to lose some potential output. It is what it is.

So my question is really what should I get, and where? Northern suburbs/West coast preferred but not essential

 

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Just a thought, the panels lose efficiency after about 3-5years and drop by around 5-10% anyway, so get panels that wont exceed your VOC, 335w or similar,try to keep each string the same, and add to existing array.

Alternatively if you had multiple arrays pointing say east and west, one could use existing panels to carefully oversize an array, position the panels in such a way that enough get direct sunlight say in the morning, the oversized portion getting less light, and it swops around in the afternoon, that way it will give a you a more flat peak on your PV curve, you will generate on one array for more hours, and not exceed your MPPT limits? It will depend on your system  configuration, and may need some experimentation.

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Since you have 6 existing, if the 6 new ones a physically the same dimensions and mounts, I would series up one old + one new and therefore end up with 6 pretty similar 2 panel strings... I have 8 panels mounted on a north-south pivot, so I have them east in the morning, bringing them further towards the horizontal by mid-day and then further to the west in the afternoon, but this is a ground mounted affair and one does need a wee bit of space for this and not too many tall items around the panels to cause shadow.

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I have a flat roof that's completely unshaded and would be amenable to a pivoting assembly but no idea how to do it. How is yours managed and powered?

I thought of stringing old and new together but my search has led me to 2 options. I can get a 305w panel that matches voltage and probably amperage of my 5y old 315s, but is physically smaller. Or a 340w panel that is physically the same size and matches the voltage. My feeling is to string them separately to avoid derating the new panels to the old ones rating.

Edited by Hagu13
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I can only show you a photo or two of the bloudraad en tang affair we temporarily put up here, as for moving it, I'm doing this by hand at the moment, long term I'll be looking at a larger structure where I'd have all panels swinging back and forth and driven by a worm gearbox with, possibly an Arduino as the controller and with some near realtime clock data to determine the best angle, I don't care about getting maximum smoke down to the last watt out of the panels, as long as I'm getting within 200W of what it can achieve, I'm fairly happy. (One can mount a sensor and follow the sun, but I reckon, waking up every 10 or 15minutes and moving the array onwards a little bit, would be more than perfect, since right now, doing this manually, I have them east, by 9-ish I move them, again by 12-ish lay them flat, by 1400-ish I point them 45 degree to the west and by 1600-ish make them face west and it works fairly well.)

I'm attaching two photos that show the panels to the east, just before I turn them to app. 45degree up to the east and then after I turned them, the 9 panels to the left in a row of the 4 and 4 rotatable ones, are fixed app. North.

The attached power curves was for yesterday the red line, obviously being the panels that change orientation and the blue cuve are the 9 fixed panels, at peak the 9 panels produced app. 2k2W and the 8 panels just shy of 2kW, 1971W to be exact. Either way, if you look at how much earlier and how much later the 8 panels make electrons run around the cables, it seems like more for less, but one would have to put up a somewhat sizeable structural marvel to ensure that winds & all don't cause any grief.

0-02-05-8c555576e673a8a0912f462b51288edfd0961a46701cbec93c51b8464c99facc_full.jpg

0-02-05-7b479b981e08c0b5b951d754ff0b277b954e7d2eb838538ae525292b4e9586a5_full.jpg

Screen Shot 2021-02-17 at 09.24.27.png

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Oh forgot to add that the tree that can be seen to the left of the photo is actually a treeline that stretches east south eastwards and this time of the year keeps the panels in shadow until nearly 8 in the morning, thus I will be relocating all panels closer to where I was standing and more to the north (the right of the picture) to get away from the trees and produce more power yet per day in the summer daytime.

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