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Originally posted by J.P.M.
helps minimize the additional cost. The south facing can be tilted; need to get them
vertical before snow. Bruce
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The east facing and west facing are a fixed, DOUBLE SIDED array, near vertical. That
helps minimize the additional cost. The south facing can be tilted; need to get them
vertical before snow. Bruce -
10 sun hours
Really good sun day today, not perfect. Set a record of 146 KWH, or 9.73 SUN HOURs.Originally posted by bcroe
Still trying for 10, maybe I need more east facing panels..... Bruce RoeComment
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Perfect sun, got a record 148 KWH. But that is still only 9.86 SUN HOURS on one of theOriginally posted by bcroe
longest days of the year. Cutting some trees would get me 10, but some belong to my
neighbors. Bruce RoeComment
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More simulation efforts
Just got my electric bill for June, with longest sun days of the year. My
inverters logged 3171 KWH after subtracting my (600' loop) line loss of 3%.
That is pretty much on target; maybe 4000 would be possible with no clouds.
THAT will never happen in NW ILL, the longest day of the year was covered
by a week of storms, seen over much of the country. 2684 KWH were exported
leaving 491 KWH used. I did run the A/C some; otherwise that would be
more like 330 KWH. So my numbers are very close to those of the power
co and design intent.
There are still 34 panels not yet deployed, need to work out positions to
boost early & late sun day production. Additional panels of any alignment
will also boost cloudy day production, currently running 30% to 70% depending
how thick the overcast is. Spotty clouds run more like 80% to 90%.
Perhaps I have found a way to use PVwatts, to simulate an hour by hour
output for each string alignment. The idea is to use different panel alignments
to get a flatter summed power curve over the sun day, and over seasons.
Adding together the hour by hour points of the different curves will give an
overall curve for good sun. Under clouds pretty much all panels come into
play, no matter what direction they face. At least that is what my clamp
on ammeter has been telling me.
The problem with PVwatts, is it includes the hour by hour effect of clouds
for the specified area, perhaps an actual recent measurement. That means
it can't be used as a design tool for good sun. HOWEVER, perhaps it
could be used by specifying an area having very little clouding. I tried
using STOVEPIPE WELLS (near DEATH VALLEY), and suddenly the curves
looked pretty good. My work has been done using curves for 19 June, 19
Sept, and 19 Dec to cover the seasons. DEATH VALLEY is farther south
than here, but I think that will mainly affect the length of sun day and sun
intensity, to a small degree. Since I want to see the RELATIVE shape of
curves (not absolute values), I think this will be pretty close.
There might be a sunny place closer to my latitude (N Cal?), but perhaps
clear skies are much more important than latitude. I'm seeing that vertical
south facing panels in Dec work almost as well as a much lower angle in
June. Maybe even better, with reflection off the snow. Not so well in Sept.
So the snow accumulation avoidance plan will be get them vertical for the
duration of serious snow. My east and west facing panels are already near
vertical, for sun near the horizon. Last year they picked up far less snow,
even though the south facing had their back to most incoming snow.
May & June banked 4308 KWH, that's 160 gallons of propane I won't be
buying next winter. Bruce RoeComment
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Trip out voltage
New experience today. My FRONIUS IG inverters have detectors to shut down if line voltage
gets out of range. However they are designed to handle up to 277VAC, so even a very high
240VAC circuit is no threat.
My line voltage has always been quite high (over 120 or 240), and pushing 58A back through
a 600' loop of 4 gauge adds about another 9V. For a year I occasionally noted a high line trip
code, which soon reset itself.
After the recent storm & outages, my line is higher than ever. An inverter would come on
and voltage went up. The second inverter would come on, and the first would trip out.
After a while the first inverter would come back on, and the second would trip out.
So for the first time I got into the Fronius setup menu. Default high line limit was 264VAC,
which is where it was lately running. Optional was up to 287VAC, I raised it to 284. It still
tripped, because there was also a neutral monitor set at half, 132VAC. That I raised to 142
and now everything seems to be fine.
On reflection I don't see any reason to even have a neutral monitor. There is no current
there, and the inverters have the option (a DELTA option) to run 240 with no neutral. Seems
to me it would be less complicated to run that mode, no neutral wiring even required.
I also reduced start up from 5 minutes to half that. Why wait 300 sec? Bruce RoeComment
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ONE YEAR of OPERATION
At the anniversary of startup, my installer came to see how things were holding up.
It had been running at max power all day long, and everything was warm to the touch
including the 4 gauge wire carrying 58A AC output. The inverters had logged 26,800
KWH despite a rather cloudy past year, exceeding predictions for the 15KW AC system.
Thats equivalent to 1000 gallons of propane, enough to get me through a fairly cold winter.
Everything looked like the day it was installed; no PV component failures. The
installer commented on running the inverters at maximum so many hours every
day. We shall have to see, if their life span is dominated by the calendar, or hours
a day at maximum, or total number of KWH produced. I have a spare.
Operational problems included a couple wiring issues. Relocating one so that an
array could be fully tilted, I managed to blow a 1A GFI fuse. I concluded that both
DC wires should be opened by the DC disconnect switch, so I added a second switch
allowing breaking both wires on each system half. A 40A circuit breaker had failed.
High line voltage here was causing false trips, though well within inverter capability.
Checking the archives revealed only my last 500 posts are accessible. So at 600+,
every one I make drops another early one. I was going to compare some of my early
system calculations & expectations with what actually happened, but guess that will
have to be from memory. Bruce RoeComment
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They are probably accessible, Bruce. They just may not be showing up on historical searches.
I'm not very familiar with vBulletin forum software. Personally, I use IPB. But, search history can be changed. Members on one of my forums complained about it being too short, like going back only one year. So, we changed it a couple of years ago to extend it to very early posts.
If I may, Bruce, how large is / are your array(s)?PaulComment
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There is a lot of detail on it just by reading thru all of this thread. You can get moreOriginally posted by livingincebu
explanation & pictures on my PHOTOBUCKET; just click bcroe , then ABOUT ME
for the link. 6 albums under ENERGY CONSERVATION. Bruce RoeComment
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The first was finished by mid June (they didn't put in the NET METER till 31 July). Digging theOriginally posted by SunEagle
E-W foundation started in Oct, so G Earth must have been between those dates. The E-W
strings are 10 panels of 72 cells, the S are 12 panels of 60 cells. Same string voltage. BruceComment
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Other PV Arrays
I hope the inverters last 5 years. I view them like tires: use them till worn out, then replace.Originally posted by SunEagle
There is an array west of Crestview, but like mine, its nearly impossible to see from the road;
I haven't made contact yet. There is a really massive commercial array on the south side
of the airport, half a dozen miles to my east. Its also practically invisible from the road. The
factory that built those panels is near by, haven't heard much about them lately.
Bruce RoeComment
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