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Managing and using your generated power - a whacky idea?
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<blockquote data-quote="ProDave" data-source="post: 255345" data-attributes="member: 6969"><p>The challenges I have yet to solve are power monitoring. A simple current transformer will tell me how much is flowing, but not which way. So monitoring grid current won't help me much.</p><p></p><p>I have a separate CU for the PV and a main CU, so I can independently monitor generated power and used power, without being troubled by which way (they can each only flow one way)</p><p></p><p>So when generated power exceeds used power by lets say 700W that will trigger the contactor to close.</p><p></p><p>As soon as the contactor closes, used power will increase by 700W, so it's no good just making the same comparison to determine when to release the contactor (otherwise it would release straight away). For that you need to compare generated power with used power, and when generated power is less than used power by say 100W, turn off the contactor.</p><p></p><p>Now this all could be designed with some basic analogue electronics. But I's rather do it with a microcontroller. That will allow switching thresholds to be easily tweaked, adjustable hysteresis, and probably some timers (to stop the contactor opening and closing every few seconds whenever the sun goes behind a cloud)</p><p></p><p>Having been out of the controls industry for nearly 10 years now, I don't know what's about in the market at the moment. Anyone care to suggest a simple programable device? must be cheap and be available in 1 off quantities as an evaluation board or OEM module, must have 2 analogue inputs, a couple of analogue outputs would be nice (but not essential) and some digital I/O. The programming software must be free or dirt cheap.</p><p></p><p>I saw a device the BBC are pushing mentioned on the tv recently but don't recall the details. They are trying to do for programming now, what the BBC micro did in the 1980's. This device will cost about</p></blockquote><p></p>
[QUOTE="ProDave, post: 255345, member: 6969"] The challenges I have yet to solve are power monitoring. A simple current transformer will tell me how much is flowing, but not which way. So monitoring grid current won't help me much. I have a separate CU for the PV and a main CU, so I can independently monitor generated power and used power, without being troubled by which way (they can each only flow one way) So when generated power exceeds used power by lets say 700W that will trigger the contactor to close. As soon as the contactor closes, used power will increase by 700W, so it's no good just making the same comparison to determine when to release the contactor (otherwise it would release straight away). For that you need to compare generated power with used power, and when generated power is less than used power by say 100W, turn off the contactor. Now this all could be designed with some basic analogue electronics. But I's rather do it with a microcontroller. That will allow switching thresholds to be easily tweaked, adjustable hysteresis, and probably some timers (to stop the contactor opening and closing every few seconds whenever the sun goes behind a cloud) Having been out of the controls industry for nearly 10 years now, I don't know what's about in the market at the moment. Anyone care to suggest a simple programable device? must be cheap and be available in 1 off quantities as an evaluation board or OEM module, must have 2 analogue inputs, a couple of analogue outputs would be nice (but not essential) and some digital I/O. The programming software must be free or dirt cheap. I saw a device the BBC are pushing mentioned on the tv recently but don't recall the details. They are trying to do for programming now, what the BBC micro did in the 1980's. This device will cost about [/QUOTE]
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Managing and using your generated power - a whacky idea?
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