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I decided I would try out the blog section. This is just a bunch of random thoughts I'm tossing out in the form of a letter. I've learned a bit this week and thought I would share.
First... I had my battery bank setup with bus bars. A guy in our maint. shop at work cut me some bars out of stainless bar stock. I drilled the needed holes at my shop at home and installed the bars. I thought it all was working very well. I was talking to another maint. guy this week and we were discussing my battery bank. I told him about the bus bars. He gave me a puzzled look and asked why I would use stainless steel. He then brought out an electrical book that told the conductivity of metal. The base line was copper at 100% conductivity. Silver was 102% conductivity... Gold was 71.2% ...aluminium 68.4%.......etc... next to the bottom was stainless steel at 2.5% conductivity!!! in other words it was 97.5% more resistant to electrical flow than copper. Needless to say I was shocked. I have now purchased some copper bar stock and made some more bus bars. My battery bank has been corrected. I feel much better.
Second... after looking at all of the awesome setups that you guys have I decided to change the way my bank feeds my inverters. When I purchased the copper bar stock I also purchased some copper bus bar that was from an electrical panel. It is 1/2" thick and 3" wide. It has predrilled and taped 1/4-20 holes. So I cut it in two (the two are about 10" long now) so I could make two power distribution points. I have now hooked my battery bank to the distribution bars and hooked my inverters to the distribution bars. I figure this will put an even pull on my two banks. Also you can see from the way the charge controllers are hooked to the banks. The controllers are at the bottom.. the inverters are in blue and in the upper right. The copper bars are in the upper left.
Now that I have my inverters feeding from their own lines off of the distribtion blocks I found another problem. When I run all items in my shop I pop my breaker that is between the battery bank and the positive bus bar. The breaker is 250 amps. Now that sounds huge, but that is 250 amps at 12v DC , which is 25 amps at 120v AC. That is an issue. My inverters are capable of 45 amps if they were fully loaded. So I have ordered some 400 amp breakers. This will give me 40 amp at the AC side. It should solve my problem. Before I setup these bars I did not have a breaker between the battery bank and the inverters (bad move I know.. but i didn't think of it at first) so I didn't run into this problem.
Third..... I have changed my panels from a 12v setup to a 36v setup. This is to better take advantage of my two solar arrays and charge controllers. It was pointed out to me by Dale that when I was running full power at my shop my controllers were showing 71 and 37 amps respectively, but that the voltage was down to 13v coming in and 11.8v going to the batteries. This was because I was running so many amps thru the 1/0 gauge welding wire that the line loss was pulling alot of my power. So I have now rewired my panels in a series of 3 panels (36v setup) and then put the series in parallel with each other. This gives me 42v - 44v while the panels are charging, once they reach float charge the open voltage is 60v - 61v . So now whenever I am running full tilt the input voltage from the panels stays above 36 volt.. the output voltage is steady at 12.3 (the bult voltage for the trojan batteries I use) and the amps between the two controllers is staying pretty steady at around 116 amps combined.
Well.. this is my first entry into my "random thoughts" blog. Hopefully it will either help someone to not make my mistakes... or point out more mistakes I've made. If it is the second option.. then I will take the information you guys provide to make a few more changes. At this point I have passed the level of professional mistake maker.. I am now an expert mistake maker.
7-19-11 Second entry
I didn't know how to continue these ramblings.. So I'm just adding on to it. I figure if it is wrong, someone will let me know.
I've changed my home system (not the pole barn) to a grid tie inverter (GTI). I was using 30 panels connected to a BZ products MPPT500 charge controller. This kept a battery bank of 5 deep cycle 125 ah batteries charged. I have decided to try the GTI so I can get the most out of my panels. The GTI I bought is a cheap unit from ebay. It is listed as a 360 watt unit but actually it is a 300w unit with a 360w peak. Because of this I moved 9 of my panels to my pole barn leaving 21 panels on my home. This should get me very close to the 300w rating of the GTI.
My home is my first attempt at solar with the HF panels. I started with 2 kits about 3 years ago. I added one battery to the mix and was using the HF charge controller. As I started adding more kits, I started blowing the fuse on the controller. So I did a bit of research and figured MPPT was the way to go. Bz Products is made in the USA and seemed to make a good controller on the less expensive side of MPPT controllers. It was a really good choice the unit has been great and always is using the extra voltage to make the extra amps my batteries crave.
There are many mistakes I have made along the way. I will chronicle them as I unload my story into this blog. For now I will just hit a few of the pieces. Once I setup my panels and my battery bank I decided to run 12v from the bank to all of my rooms. It seemed easier than keeping an inverter under my home (it is on a slab) and running AC to the rooms. DC seemed safer also ( a big concern of my wife ).
Once I ran the DC to each room I then used old UPS units to convert the power to AC in each room. I just removed the batteries they had and added a connector so that I could plug them into my DC outlets in each room then closed the units back up. Now they looked normal and instead of having an AC plug on the end of the cords they had a DC plug. We have been using lamps in each room instead of the ceiling lights when are bank is full. This is most all of the summer. During the winter I would regulate which rooms would use solar power and which would use the ceiling lights.
OK.. sorry I have to cut this short.. but I have an errand to run... later tonight or tomorrow I will add more.
7-26-11 Third entry
Well it has been a week since I got my GTI to try at the house. I now have a question. The unit is sending power to the house as proven by my kill-a-watt. But I seem to have grown attached to my battery bank and the lights that are powered by my own energy. So I want to use my panels to charge my battery bank every other day. The odd days will have the power sent to the GTI. I can run the lights for 2 - 3 days without a charge. If I charge them every other day. All should be good.
I've seen a transfer looking switch in some of the pictures. I want a switch that I can hook both the charge controller and the GTI to. I can then manually switch the panels power between my GTI and my charge controller. Is this something I can buy locally at a home center? I will be doing research to figure it out, but thought that some of you may already have the answer. Let me know.
Ok... enough with the questions... I will add more ramblings to my blog.
This weekend was productive. As alot of you have seen I completed the installation of the final panels on my barn roof. They are nearly edge to edge on the roof and are three rows deep. When I started the project I wanted a better way to attach them to the roof. One that did not involve wood, since my first attempt at a roof rack was made with wood and it started to rot after two years. The second part of the challenge was that this is a ribbed metal roof. So I was walking around lowes looking at the different materials that I could use and was dreaming of how to attach them.
What I came up with was man made decking , PVC trim pieces, and vinyl siding J - Chanel. So it works like this. I bought a 16' decking plank. This material will not rot and is flat on the top like a board, but the bottom has three humps for strengh. I will explain what I did and then add my crude MS paint image. First I cut the board into 1.5" pieces and then made a jig on my drill press so that I could put two of the pieces at a time on the press and use a spade bit to drill the center hole larger. I could then use these pieces as a stand off on the roof. The center hole goes over a roof rib and the side holes allow for rain drainage. The lifts the panels off of the roof about 3.5" at the bottom of each panel and 4" at the top of each panel. Here is the crappy illistration of what they are.
Links to the decking and the PVC items.
So.. I put one of these base units every foot over a rib on the roof. I predrilled a pilot hole in the center of each one and then used silicone caulk under each unit where the screw would go. I secured them all to the roof using 3" screws into the rafters. I then used PVC moulding and furing strips. They are solid plastic and are made to be used instead of wood for outside crown moulding and base strips. I secured the moulding to the bases across the roof and then attached the PVC moulding to the bases. Once the moulding was attached to the bases I screwed the J-channel to the PVC. This is where the top of the panels would snap into place. For the lower end of the panels I used the PVC board it was about 1" thinner than the moulding that was used at the top. I figured this would give a bit more angle on each run of panels. I repeated the attachment procedure for the J-channel for the bottom of the panels. Once I got the entire row ready it was easy to then go down the line and snap each panel in place with the J-channel securing the top and bottom of the panel. The wiring runs under the panels down to the central combiner boxes.
Sorry.. gotta run.. I can explain in more detail if there are any questions.
8-2-11 Fourth Entry
Well I think I have figured out the "transfer switch" that I was questioning earlier. I am going to keep both the battery bank and the GTI hooked up and switch between the two items as needed. I will be using a 3 way 15 amp light switch. I will hook the positive from the PV to the common on the light switch. Then run a line from one pole of the switch to the charge controller and another line from the other pole to the GTI. The negative from the PV will go to a ground bus bar. Both the charge controller and the GTI will be hooked to the bus bar with their negative terminals. This should give me the complete ability to switch between the two devices with just the flip of the light switch. I will mount all of it on a board. Once I get it done.. I will add a picture.
Well a small set back with my solar powered barn. I had an inverter fail this weekend. I listed it on the forum under the title "inverter failure" . It was my PowerBright 3000w pure sine unit. This unit powers all of my outlets in the barn as well as the outside outlets for use in the yard. I don't know if this pushed the unit over the top, but I do trim around my house, barn and trees with an electric lawn mower. It is the Sun Mow Joe and it has worked great.
Well anyway I was trimming after I mowed the lawn and the unit stopped. I checked the lines and found all in good order. I went to the barn and smelled burnt electronics. I will tell you that made me walk a bit faster thinking the worst of course. I found the smell was coming from the powerbright. It was still on but the output meter was at 0 . The unit has been sent in for repair or replacement. We will see how it works out. The unit was running a fridge, radio and the mower at the time.
I have completed the hardware of my sunforce 4500w pure sine that will be running part of my home. I rented a trencher and laid the line between my barn and my house. I have installed the conduit in the barn on both the outside and the inside. The conduit to the house has been installed on the outside thru the wall but has not been completed to the breaker box yet. I will be working on that this weekend. The box has 8 breakers installed, four 20 amp and four 15 amp breakers. I will be running the lines and should be able to switch between grid and solar power on most of my outlets and room lights when I'm done. More on this as I get it done and get pictures.
I have also wired and installed some DC lights in the barn. That way when I'm heading in and out at night I don't have to power on the inverter to run the regular CFL lights that I installed. Instead these are the lights from the HF kit. I ran the power direct to the 12v distribution bars and installed 3 lights and a switch in the office and 7 lights and a switch in the barn itself. So when I first open the door I flip the switch and the 12v lights form a trail from the ceiling to the office. The office is where my inverters and battery bank are located. I then turn on the office lights or just go in and turn on the inverter. I have finally found a use for the 12v lights.
I will add some more as I go along, at this point I just ramble a bit.. as the title of this blog eludes to.