Optimal usage of 10 used 250 watt panels?

softdown · December 1

Need more summer time production due to quite a number of fridges and freezers. Existing array is at 45 degrees with latitude of 37 degrees. Awesome winter time production.

Lots of room left on this flattish roof ~ 2.5 degrees. Roof is 45’ wide.

So many options exist for adding panels. I have two 100v charge controllers that will each handle two panels in serial. Could easily get two 150v charge controllers that will each handle three panels in serial.

Would be efficient to lay a strip of angle iron, guessing here, ~18” above the flattish roof. And attached to the upright tan gable end. Good summer time angle is, what, about 20 degrees or so? Angle iron strongly secures the panels at the desired angle.

Without much analysis done this configuration seems acceptable:

3 panels pointed EAST

3 panels pointed WEST These panels would do quite well judging from summer time sunlight production.

4 panels pointed SOUTH - already have 18 smaller panels pointed south but at 45 degrees. Summer time production consequently suffers.

Image: https://us.v-cdn.net/6024911/uploads/editor/33/2ow2g6vm3fkn.jpeg

softdown · December 2

1000 watts at 14 degrees pointed east:

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( kWh )
January	2.87	73
February	4.12	96
March	5.39	137
April	6.54	157
May	7.35	177
June	8.08	182
July	7.33	167
August	6.62	152
September	5.65	130
October	4.40	108
November	3.38	83
December	2.75	70
Annual	5.37	1,532

1000 watts at 2 degree pointed south:

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( kWh )
January	3.04	78
February	4.24	99
March	5.53	140
April	6.65	159
May	7.41	177
June	7.94	178
July	7.15	162
August	6.52	149
September	5.71	130
October	4.56	111
November	3.58	87
December	2.95	75
Annual	5.44	1,545

1000 watts at 20 degrees pointed south:

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( kWh )
January	4.32	112
February	5.48	128
March	6.36	159
April	7.02	167
May	7.33	175
June	7.65	171
July	7.03	158
August	6.74	153
September	6.42	146
October	5.72	140
November	4.99	123
December	4.32	114
Annual	6.12	1,746

12% more output than simply laying the panels flat. Negligible difference during the summer however.

1000 watts at 14 degrees pointed west

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( kWh )
January	2.86	73
February	3.97	92
March	5.24	132
April	6.35	152
May	7.16	172
June	7.49	168
July	6.63	150
August	6.05	138
September	5.37	122
October	4.30	105
November	3.34	81
December	2.76	70
Annual	5.13	1,455

9% less output than easterly oriented panels. Surprised at that. The west sun seems to hang forever during the summer - providing daylight until ~8:30pm. I suppose this is assured mathematically.

softdown · December 2

Simply laying the auxiliary panels flat comes astonishingly close to angled panels in output. Eliminating the need for racking and the possibility of roof leaks or wind damage.

On the other hand I’m sure that angled east and west panels would start and maintain production for a longer period of time. I’m not sure what those numbers would be however. Early morning and late evening sun is notoriously weak in terms of solar production.

NANOcontrol · December 3

I have an array facing due east and they are highly productive. I think they are an ideal solution, power when you need it most first thing in the day. Greatly reduces the need to store power. Batteries are recharged and water heaters turn off by 10am so I can run the dishwasher.

softdown · December 4

Yes with prolonged charging periods it seems self evident that east and west arrays would favor battery longevity. But their production suffers in the winter in northerly latitudes.

Northern winters already blow. Northern winters are not made for old men. One has to work at keeping up their critical vitamin D levels!

Optimal usage of 10 used 250 watt panels?

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