Second system (plagiarism edition)

[Stinsy]

As avid readers of this forum will know, since my neighbour felled the mahoosive tree earlier this year, the one that previously overshadowed my "shed" (garden office), I've been making noises about getting a bit more oomph kWp-wise.

My current 4.08kWp system produces all the electricity I can use on the very sunniest summer days, but most of the time I rely on Octopus 5p cheap rate to charge my batteries and avoid expensive peak-rate electric. As soon as the shoulder months kick in I'm using peak electric ( ). So a bit more solar will: reduce peak electric usage in winter, reduce cheap rate electric in summer, and provide a bit of extra free electric on the sunniest days to charge the BEV (that is hopefully coming in December).

I have managed to source 3x 380W JA Solar panels. Today I put them on the roof of the shed (pics below). Tomorrow I'll wire them to the battery/inverter position in the attic. I just need to source some kind of charge controller, does anyone know where I might find something suitable?

[Joeboy]

I can't see your photos but going on the enthusiastic vibe and being back home tail working end next week I might be able to help. PM?
P.S regardless of my photo blindness due to phone, well done! Truly applauding!

[nowty]

Regarding charge controller, do you want bluetooth smartphone monitoring ?, or cheap and cheerful ?

Could you not get 4 panels on that roof ?, looks a bit non symmetrical with 3.

[Mr Gus]

Overhang is a form of weather proofing / shading after all.

[nowty]

Regarding a charge controller, the problem you have is with 3 in series, the voltage is too high for most of the cheap ones and 3 in parallel the voltage is not high enough for even the MPPT ones to work very well if at all.

I ran it through the Victron calculator, you'd need all 3 in series for a 150/35 which is pretty pricey, but would be great if you could find another place for a second string of 3 panels.

If you could fit 4 panels, then 2 parallel strings of 2 in series would be ideal for the cheaper 100/20 one. Also other cheaper brands would work too with that configuration.

https://www.victronenergy.com/mppt-calculator

This one might work with 3 in series if you don't want to pay Victron prices.
https://www.ebay.co.uk/itm/203644534798 ... SwB6RezMBl

[Stinsy]

Could you not get 4 panels on that roof ?, looks a bit non symmetrical with 3.

I spent a huge amount of time looking for panels that could fit on a 2.4x2.4m roof in a 2x2 array, no joy unless I wanted a 30cm overhang all round and the shed is too close to the boundary for that, so I went for 2x portrait 1x landscape arrangement that reminds me of tables at school.

Regarding a charge controller, the problem you have is with 3 in series, the voltage is too high for most of the cheap ones and 3 in parallel the voltage is not high enough for even the MPPT ones to work very well if at all.

I ran it through the Victron calculator, you'd need all 3 in series for a 150/35 which is pretty pricey, but would be great if you could find another place for a second string of 3 panels.

If you could fit 4 panels, then 2 parallel strings of 2 in series would be ideal for the cheaper 100/20 one. Also other cheaper brands would work too with that configuration.

https://www.victronenergy.com/mppt-calculator

This one might work with 3 in series if you don't want to pay Victron prices.
https://www.ebay.co.uk/itm/203644534798 ... SwB6RezMBl

All charge controllers need the string voltage to be above the battery voltage to work, usually by 5V to start and 1V to keep running. These panels are 42Voc so a parallel string would work well in a 24V system but no good for a 48V. So the string will have to be series.

I had been looking at the Victron 100/20 when I was planning 2x mahoosive 540W panels (but they sold out while I hesitated). This array is 126V Voc so the 100/20 is no good. I’m very wary of the eBay-quality charge controllers, I’ve read that they are frequently: poor quality, inefficient, and shortlived, many are reportedly PWM models fraudulently mislabelled as MPPT. That Victron 150/35 really is the correct tool for the job but is sure is pricey! A “150/20” would be perfect but no such thing exists.

[Joeboy]

You'll get there!

[nowty]

I know its too late for Stinsy as he has already bought and fitted the panels. But for the benefit of others, Panasonic panels with their inherent higher working voltages could have been used all in parallel with the cheaper charge controllers including the 100/20 Victron charge controller. But it is swings and roundabouts as Panasonic panels tend to be themselves more expensive. But they are available in several different size formats which makes fitting the maximum to a particular roof size easier.

[Stinsy]

I know its too late for Stinsy as he has already bought and fitted the panels. But for the benefit of others, Panasonic panels with their inherent higher working voltages could have been used all in parallel with the cheaper charge controllers including the 100/20 Victron charge controller. But it is swings and roundabouts as Panasonic panels tend to be themselves more expensive. But they are available in several different size formats which makes fitting the maximum to a particular roof size easier.

I’d seen the Panasonic panels, it is an interesting concept, they do a “compact” and a “slim” panel. However they’re priced around £1.50 a W in a world where 30-40p a W (inc VAT) is normal. The Perlight 1.5m panels are more reasonably priced “compact” panels. However irrelevant of price I couldn’t make them work for the size of my roof.

I hadn’t considered voltage as a metric by which to differentiate panels…

[Tinbum]

I hadn’t considered voltage as a metric by which to differentiate panels…

The insurance company are trying to find a replacement panel for one of mine that has an earth leak and it's the voltage that is causing problems as they are 60.5 VOC