ewdudley
Minister of Fire
Depends on your definition of morning, I suppose. In a strictly solar sense, the morning sun has been earlier relative to solar noon ever since 21 December this particular year.
Solar electric 6.5kw expanded to 12.3kw
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ewdudley
Minister of Fire
Right. So when I look up a town a hundred kilometers to the east of me it says the sun rises a six minutes or so earlier there. Does that mean they get more sunlight? Of course not. The elevation of the sun at solar noon, and therefore the time from sunrise to sunset, determines the maximum amount of sunlight available in a solar day. In the northern hemisphere the time from sunrise to sunset has been increasing since 21 December of this year.
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mr.fixit
Feeling the Heat
This is another sun position calculator that is kinda cool, http://suncalc.net/#/51.508,-0.125,2/2013.12.29/20:12
Brick (ware)House
Member
Search the web and you should find design ideas from the many prefab carport arrays currently being manufactured. Be aware that even modules that are racked extremely close together will allow rain and water to run through. They will keep the snow off and provide shade but the snow melt and rain will penetrate unless the racking system is designed specifically to shed all the water to the edges.
Brick (ware)House
Member
Depends on the peak output of the modules. My ~29 kW system is about 2,000 sq. ft. using 305 W modules. There are two standard sizes of modules, 60 cell and 72 cell, with multiple peak output ratings within each size.
DBoon
Minister of Fire
When I priced out my solar array, I found pretty quickly that a tiltable rack added a lot of expense and that it was cheaper to just add more panels on a fixed rack.
Brick (ware)House
Member
That's all most always the case. My panels are racked at about 10 degrees instead of the optimal 35 degree angle for my location. The result is approximately a 7% reduction in annual output (around $280 worth of electrons). A high angle was structurally impossible and a variable tilt or tracking system couldn't begin to provide the increased output necessary to amortize the additional cost.
As a solar wannabe, this is a most interesting thread.
Thanks for sharing your experiences.
Thanks for sharing your experiences.
Brick (ware)House
Member
Redbarn - Let me know if you have any specific questions and I will do my best to answer. The little project seen in the top of my avatar taught me many lessons! I haven't been out there since high school but I love your part of the country.
Thanks for the offer.
I'm not ready for our solar system yet but I find reading about the experiences of people who have done it to be particularly interesting.
Clear sky and -6F cold, and at 1:00 pm panels are producing 5.6kw or 81% of rated output, and that is with the sun at a little over 20* above the horizon. No comment regarding the very cloudy days and snow covered panels. Uggh.
You will not believe me, but eventually 95% of the folks with solar start to ignore the system. In the short term its interesting stuff but eventually it get to the point where you hardly ever look at it. That's the way it should be, just another appliance.
I do believe you, but this early high level of interest is to help me understand how it works, things to watch out for, and quickly solve any problems that arise. One thing I wanted to pay close attention to was the kwh being sold back to the utility to make sure the system numbers matched what the utility was giving me credit for. So far the numbers match.
The system has shut itself down and would not restart without a power off and on reboot on four occasions so far. As best as I can tell, this happened at extremely cold temperatures (below -20F) and also snow covered panels. Those two factors may have been coincidence, I don't know. This morning it was -29F and I cleaned snow off the panels before the sun had cleared the trees which shade the early morning production, and as soon as the panels picked up the sun they were active and the system did not shut down. So, I still don't know exactly why the shutdowns before.
The system monitors itself and supplies lots of data, if I want it, as well as maintaining daily, weekly, monthly and annual reports. Sooner or later that will be enough for me.
The system has shut itself down and would not restart without a power off and on reboot on four occasions so far. As best as I can tell, this happened at extremely cold temperatures (below -20F) and also snow covered panels. Those two factors may have been coincidence, I don't know. This morning it was -29F and I cleaned snow off the panels before the sun had cleared the trees which shade the early morning production, and as soon as the panels picked up the sun they were active and the system did not shut down. So, I still don't know exactly why the shutdowns before.
The system monitors itself and supplies lots of data, if I want it, as well as maintaining daily, weekly, monthly and annual reports. Sooner or later that will be enough for me.
System went active Oct 28, and now Nov and Dec have ended and I'm estimating that the morning shading with low sun angles has reduced production about 20-25% over optimal, and January likely will be the same. I don't have info to determine whether these months were cloudier than average. Assuming average irradiance, my production for Nov was 65% and for Dec was 60% of predicted. But even at these levels the panels since going active have been producing close to 100% of our general service electric usage. Soon they will cut into electric for dhw and supplemental electric heat usage.
In the northeast November and December are the worst months for sun. Usually January and February may be cold but more sunny days.
With longer days starting and a higher sun angle we are starting to get some production again. Just a few hours at this time of year, but that's better than none. It will be picking up rapidly now as long as it's sunny outside.
My awe will dissipate as the first year of solar runs its course. Tue and Wed were two successive clear days, panels produced 26kwh each day, and peak output was 6kwh for about an hour on Wed, that's 88% of rated output.
Former Farmer
Minister of Fire
I have a 10.2kw system mounted on the roof of my shed. 18* pitch. This will give you an idea what to expect as the days start to get longer.
The system is comprised of 40 255w Solarworld panels with Solaredge power optimizers and Solaredge inverters. System went online in Nov. 2011.
Thanks. If I read the graph right, Dec '11, '12 and '13 were respectively about 450, 330, and 440kwh? My Dec production was 268kwh.
Former Farmer
Minister of Fire
443, 300, 435.
Your 268kw divided by your 6.5k system equals 41.23kw per 1k of system. My 440kw divided by my 10.2k equals 43.13kw per 1k of system. So our systems are pretty similar to each other.
Right now I have 4 of the panels are not producing because of snow cover. It isn't enough of a loss for me to spend over an hour to clean them off. I will wait until more are covered with snow or the sun melts them off. This is one advantage of using micro inverters or power optimizers versus just a central inverter.
