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Tom & Cindy's Test Site - Page 2
The MidNite beta system has 12 Kyocera KC130’s all in series. The open circuit voltage typically runs 249 volts during this time of year. The distance is about the same as the original PV array, but for this beta test we used an entire 500 foot roll of 8AWG wire. The extra wire is wrapped around their massive water tank in order to use all 500 feet of wire. We intentionally put the Classic at a disadvantage both in the length of wire run as well as wire size just to see how it would work. 8AWG wire was also a lot less expensive than 6AWG. Our initial calculations told us it should work just fine. Even though we had a 250 volt prototype operating for a year or so, it had not been put to the test under real conditions. Our first ten tryouts at the site were less than encouraging (the smoke got out). This high voltage stuff is not easy. boB finally got the bugs out of the unit and we were able to watch in amazement how cool this thing really is. One of the issues on doing high voltage is that the higher the voltage, the higher the losses. We were pretty sure that we had done our homework and were onto an industry breakthrough. Some of the tricks we have designed in are not even in the beta units yet, so performance of production units will only be better than you see here. The first time we installed the Classic that had all the critical fixes in it, there was no sun at that moment. This is a common problem as we are located just North of Seattle. Because boB designed the OutBack MX60, he has a vast knowledge of what people like and dislike about charge controllers. boB probably has a better understanding of this than any other engineer in the world. One of the dislikes people have is the constant clicking of the relay during times of low light. boB planned on doing something about that problem on the Classic. I got to witness first hand how the MX60 would click the relay about every 30 seconds. There wasn’t enough sun to make the MX60 come to life, so it did what it knew how to do which was to make relay clicking noise all day long. The Classic on the other hand never clicked it’s relay. It just knew there was not enough power to warrant turning on so it didn’t make that annoying noise. We did find out a few days later that the Classic was waiting a little too long to turn on, so that is being tweaked in the firmware. We will be e-mailing new firmware to the test site to upgrade the code in a few days. boB has made the task of upgrading firmware a breeze. Anyone can do it. Have fun looking at the diagrams and pictures of the test site, then click on the link to the APRS World website that is doing the monitoring for us. APRS World built the box that collects all the current and voltage data from both arrays and controllers. Data is sent wirelessly from the power shed to the house and then onto the internet. We are not relying on meters built in to the controllers for the data. Meters on controllers are notorious for being inaccurate. In fact boB just spent many weeks redesigning the current measuring circuit on the Classic for this very reason. The circuits that have been used in controllers have ties back to the Trace C-40 which is not a very sophisticated circuit by todays standards. It is quite possible that upon checking out the APRS World monitoring, you will find that there is nothing happening. We know how to do rain very well around here. There is another link to Noah that will give you the weather forecast for Granite Falls, so you can plan a more productive visit in the future when necessary. Midnite is planning on making a half dozen of these data logged test sites, so check back often to see what else pops up. Wind turbine sites are also planned for some of these next beta sites. Back to Home - Classic Test Site
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