100KWh DIY 18650 Powerwall in Germany

Stefanseiner

Solar Enthusiast
these effects appear when combining small amounts of cells in parallel befor connecting them serial - in combination with huge currents.

I don't do both of this.
I am using huge amounts of cells in parallel (60pcs or 120p per system, and because I have several complete 14s systems parallel there are effectively 360 cells in parallel.
That in combination with a tiny current of 0,1 - 0,5A max per cell will not cause any overcharge / overdischarge in a single cell.
And a bms will take care about the voltage of the parallel packs so that a drifting voltage will not harm the system. In addition a balancer will avoid voltage differences between the packs.

You can trust me too, this system is running perfectly since last year and approved by many DIY-people all over the world who are using very similar systems.

small update:
some more pv modules to add another 1,65kWp on the roof of the balcony
phoca_thumb_l_KW28-Balkon-Solar_fertig_Hochbeete2_02.jpg


and another 600 watts at the wall
phoca_thumb_l_KW28-Balkon-Solar_fertig_Hochbeete2_09.jpg


and no, the lawn mower is not solar-electric ;)
this is just an old, defective module which protects the content of the trailer against rain

phoca_thumb_l_KW28-Balkon-Solar_fertig_Hochbeete2_10.jpg
 
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Hedges

I See Electromagnetic Fields!
some more pv modules to add another 1,65kWp on the roof of the balcony
phoca_thumb_l_KW28-Balkon-Solar_fertig_Hochbeete2_02.jpg

Does the sun ever get high enough that roof casts a shadow on them?
If so, I would rather see more tilt, rails from lower edge of awning up to eaves of roof.
 

Stefanseiner

Solar Enthusiast
sorry, but the point of view of the picture above is not very good,

but at the following picture below you can see the gap between roof and modules better. It's bigger than the roof overhang and shadow comes only when sun turns over to the west side. The balcony is exact east sided
phoca_thumb_l_KW28-Balkon-Solar_fertig_Hochbeete2_11.jpg
 

Hedges

I See Electromagnetic Fields!
Oh, I had thought it was facing South so depending on your latitude, some seasons it might clip all day long.

I would like a panel to have clear view of the sun with at least +/-45 degree angle, a 90 degree field of view or 6 hours centered on optimum angle. Daylight might last 12 hours, but most power production will be during the period when panel faces sun, drops off quickly at large angle (except during overcast.)

As located, when sun is directly overhead at Noon it isn't shaded, but shadow falls on it shortly after. Panels likely have three diode-bypassed sections of cells; does the shadow cover only one section so the other two can keep producing power (assuming suitable voltage and MPPT charger), or does the shadow take out all three sections?

More tilt of the panel would increases the numbers of hours it gets unshaded sun after the point when it is aimed straight at the sun. But it would reduce the number of hours from sunrise to when straight at sun. There would be some angle that maximized power captured, at least for a particular day of the year.

My guess is that a tilt so panel lined up with roof would be pretty good. Sun would be several hours past directly at panel before the upper roofline cast a shadow on it.
 
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