Another consideration is that the optimal direction for you may not be due south. This may be because of local conditions such as fog in the morning or shading in the afternoon, for example. If you are doing a roof mount, and your roof is not facing due south, the calculations for optimal tilt are different.
Still another consideration (affecting both tilt and direction) may be the timing of your loads. This is true if you are off grid and may be true on grid depending on what net metering arrangements or time-of-use you have. With panels as cheap as they are now it may be cost effective to have split your panels into two arrays (with two charge controllers) with different tilts and directions. If you are using microinverters you might even have more than two tilts and directions.
rss2q, tell us more about your location, climate, loads, and type of system.
4 x 235w Samsung, Outback fm60 & vfx3524 & mate, Midnite E-panel, four Interstate L16, Trimetric monitor, Honda eu2000
1900 watts PV, (1000 watts PV feeding MidNite Classic 150; 900 watts PV + 160 watts micro hydro both feeding into a single shared Morningstar TS-MPPT-60) ; Xantrex Pure Sine 1800/12 for heavy loads; Xantrex Pure Sine 1000/12 on 24/7 for everything else; six Rolls Surrette 2 volt L16 @ 12 volts.
Domestic hot water totally provided by the sun 8 months out of every year via thermal panel.
Example: PV watts says that 35 degrees is the optimal angle for year-round production at my location. For a 5 kW system, standard derate, that means a total of 6158 kWh, with 328 in December and 600 in June.
If I tilt that same array up to 60 degrees, I produce only 5679 kWh per year, but now I produce 365 in December and 459 in June. Tilting the array even more loses production in both summer and winter, unless the snow-glare effect is prevalent.
It's not a huge difference, but that way I can squeeze a few more kWh into the winter months, when the sun is scarce, and I still generate excess power in the summer months, so who cares about kWh I can't use anyway?
Here is a great resource. (sorry, US only)
This page calculates the altitude and azimuth of the Sun (or Moon) at multiple times during any day between 1700 and 2100. Simply specify the object, date, tabular interval, and place:
Our tax dolars at work.
Last edited by SolaRevolution; March 27th, 2012 at 20:50 PDT.
12 kw Generac, Honda EU3000is, 4.2 kw APC UPS powered either by battery or a Prius. Really.
I found this link here on the forum I think. I think it is quite useful.
If you didn't know shirt from shin-ola you can set the angle by
1.) know "solar noon" at your local
2.) use a 12" stake with a true, square 90* base
and place it on the panels, adjust said panels until there is no shadow.
Way too simple...
10-Astronergy 235 watt panels
Fixed 180* south face-No tracker
Midnite Solar Classic MPPT Charge Controller 250V
Mini-Magnum MS4448PAE Power Center
16(ea) S-530 Surrette Batteries 800aH @ 48VDC 38,400 watt hrs.
Lat/Long 37.8 N 113.1 W