[Greenbuilding] Solar Water Heater Tilt

[sat jiwan ikle-khalsa]

Alan here's some info:
10 months data, 2962 kwh, ~300kwh/month, ~10 kwh/day
Daily production can vary 0 (heavy rain all day) to 20 (best day); we had 12.4 kwh/day avg over the summer (Apr-Sept))

We had been calculating/aiming for 360/mo. (not sure where we got that figure)

Note: one week in Sept/Oct what we surmised as a grid surge tripped our breaker, while we were traveling so when we got back found system hadn't done production for a nice sunny week. (probably add 80 kwh to our numbers above to be more accurate)

AND for what it's worth, i tried the PVWatts calculators: (couldn't get version 2 to work, even using diff browser)
the program's calculations found very little extra KWHs/yr in a few different tilts and orientations i tried.  the help button and interpreting results button on version 1 were informative about temp and testing conditions (though i haven't taken time to understand the details fully).

for these settings, i got these _predicted_ annual outputs.:

all for my location (39 latitude)
201 orientation, 25 tilt: 3692 kwh/yr (baseline, others relative to this)
201 orientation, 35 tilt: 3726 (+34, 1%)
201 orientation, 40 tilt: 3706 (+14, 0.5%)
180 orientation, 39.2 tilt: 3757 (+65, 2%) (program defaults settings = ideal??)
201 orientation, single axis orientation: 4638 (+946, 25%)
two axis tracking: 4980 (+1288, 35%)

single axis is a big bump (25%), and two axis (only?) adds another 10%.

again, i'd love to see more real-world case studies. mine is just one, but it looks like we're RIGHT on track for the annual avg (should i have more faith in these calculators?)

-sj


~ ~ ~ ~ please use my permanent email address: satjiwan at alumni.brandeis.edu ~ ~ ~ ~



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Alan Abrams 
    alan at abramsdesignbuild.com
       

    Mon Feb  9 14:11:34 CST 2009
    
      

PV - We have a 3kw grid tied, net metered system. it's providing about 100%
of electricity in summer and maybe 50% in winter (need to update my log
sheets to check).  

>>>>>>>>>>>>>>>>


Hi Sat--

Can you tell us what that output is in KWH/mo or yr?  I just took off a
2.8kw system using a variety of algorithms and estimate its output at an avg
of 250-260kwh/mo in wash dc.

-cheers--AA