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Bob-O, I neither subscribe to the notation that cheaper is better nor the notion that more expensive is better. Adding more wire until 1%, or any other arbitrary percent loss figure is attained, does not necessarily make a project better. It will make the project more efficient to increase the wire size. But without considering the value delivered by the extra efficiency, how do you decide when to stop adding wire? The installed cost per watt (or watthr/per year) delivered is a reasonable metric to use for making the decision to use more wire or not. That is in fact the metric you and I both use to decide that using MPPT technology is a smart choice. We know MPPT technology is worth using because we get more for our dollar. If a FM 60 was the only MMPT charge controller on the market and it cost $1500, neither of us would use them as often. Since neither you nor any other wrench on this list offered an answer to my previous question, I'll rephrase it. If 1% loss is a good design, then why isn't 1/2% loss better? Why stop at 1%? I'd like to point out an error in your reasoning that extra cost is recovered over time as power prices increase. There is a point to be made there, but as you stated your argument the comparison was between future value and present value. That's an incorrect economic comparison; you have to determine the present day value of future benefits and compare that to present cost. It is unfortunate that there are getting to be fewer and fewer choices for PV modules that aren't entirely or largely made in China. It's criminally ironic that BP Solar is predicting 50% growth in PV sales at the same time they are closing their manufacturing facility in Maryland, see article. I wonder how many of those 320 newly unemployed workers will be in the market for PV systems. And how many more such jobs can be sent to China for short term corporate greed before no one in the U.S. will be able to buy one. Kent Osterberg Blue Mountain Solar, Inc. Bob-O Schultze wrote: Of course it's not a practical solution, which is why we strived for (but rarely got) 2% VD on low voltage situations as I said in my first post. The obvious reply to this post is that your scenario isn't real world anymore. MPPT controllers fixed that. Or perhaps you advocate that MPPT controllers are just too expensive too? I could easily come up with a scenario where a C40 and big wire is less expensive than using MPPT and smaller wire. But is that good design? I don't think so. |
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