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I'm contemplating various ways of using renewable energy, but I'm also interested in learning more about the subject. At the moment I'm trying to understand a few aspects:

  1. How to measure and track when traditional energy is used rather than renewable energy?
  2. What mechanism controls the switching between the two, or how is load balancing achieved when renewable energy is only 10% of what you need.
W5VO
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Jacques
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1 Answers1

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On sites with permanent power grid connection, the usual way to go is to not balance at all, regardless of consumption or production, but rather transfer all produced power into the grid, and draw all consumed directly from the grid.

You just measure production, consumption and the difference, and display that.

Because produced power is either DC or out of sync with the grid, you have to convert it to grid phase anyway. Then why switch, balance, and all that? Just put it on the grid, provided you have a contract for that. As far as I am aware, this is the usual situation for houses with production and all production sites, like small watermills or so.

On sites without permanent power grid connection, or without contract to supply power, things are of course more difficult. Sometimes, say in yachts or campers, you find two separate installations for DC and AC. Using DC to balance makes things manageable, especially if you also have batteries to buffer the energy. In this situation, most devices will be DC driven, with a few DC/AC convertes to drive systems which require AC.

If you want to balance with AC grid online, things become more difficult. For one part, the security aspects: You dont want to supply 230V to a line that is supposed to be switched off for repairs, for instance. The supply has to be aware of line being switched off and stop supplying power, etc. Personally, I would avoid this situation, because of danger and effort.

posipiet
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  • This would be a home yes. Do you have a reference to a link that could describe how a grid works? – Jacques Aug 18 '11 at 11:50
  • By grid I mean the electrical power grid, http://en.wikipedia.org/wiki/Power_grid – posipiet Aug 18 '11 at 11:56
  • Does each house have its own grid over and above the Electricity Supplier grid? – Jacques Aug 18 '11 at 12:01
  • Nope. There normally is only the Supplier grid. – posipiet Aug 18 '11 at 12:18
  • So I guess my question then is, if I wanted to reduce the amount of electricity I used from the supplier grid, instead using more solar power (or similar), can this only be done by feeding the solar energy back into the grid? – Jacques Aug 18 '11 at 12:21
  • Yes, this is the usual way. Only with great effort you can use your own electrons. I read about one guy who basically changed his household electrics to DC, like a boat... – posipiet Aug 18 '11 at 13:17
  • You need a battery bank for solar energy, because the sun isn't always in the appropriate position to help. With a grid connected solar system, you're essentially using the supplier grid as your battery. – Optimal Cynic Oct 07 '11 at 08:25
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    Additionally, it doesn't really matter what you're using because electrical energy is fungible. Sure, your toaster might be powered from Pollution Inc's spotted owl burning plant, but your neighbour's toaster is now running off your lovely clean wind turbines (which merely pummel the owls to death) instead. The net reduction in spotted owl incineration is still the same, regardless of who actually uses those electrons. – Optimal Cynic Oct 07 '11 at 08:29