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Power transfer switching?

Discussion in 'Alternative Energy' started by HarveyH42, Jan 6, 2010.

  1. HarveyH42

    HarveyH42 Banned

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    Getting a little deeper in to Solar power, and was wondering about something. It's sort of like a UPS, but in reverse I guess. I'd like to run off the batteries as much as I can, but don't want to get cut off in the middle of something. Was wondering if there is a device or circuit, that would switch to grid power, when the batteries get low. Would like it to be a smooth switch over, like the USP on my computer. There must be something like this out there, just don't what to call it, so searching has been much help yet.
     
  2. smanches

    smanches New Member

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    It's called a Grid Tie inverter. :D

    Honestly though, if you're going to run on the grid at all, grid tie is the way to go. You get all the efficiency from your renewable sources, but without the added cost of maintaining batteries all the time.
     
  3. HarveyH42

    HarveyH42 Banned

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    I thought grid tie was for putting your surplus into the grid. I'm still growing, only have 165 watts worth of solar panels. More than enough for lights, and looking to run a few small appliances and tools. Haven't gotten a larger battery, or installed all the panels yet, but won't be long. Not a great deal of power, and figure on running out often, until I get adjusted to the capacity. I've got a 1500 watt inverter, but might be a little much, says it needs a 150 amp fuse. Thinking a 100 Ah battery may not get charged on a daily basis, and that much of a load would drain it quick. Just got an 800 watt inverter for my coffee pot, but haven't opened the box yet. Thought about a 12v coffee maker, but 40 minutes to brew a pot was a little unrealistic.
     
  4. dave

    Dave New Member

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  5. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    Actual grid tie works as a co generation system.
    For example you have a 1 KW load on your system some place. If your grid tie unit produces 165 watts feed back you are using that 165 watts but then only buying 835 watts off of the utility.
    If you grid tie 1 kw you then dont buy any power off the utility.
    If you grid tie 2 kw then you use one yourself and sell the second one back to the utility or store it on their system by spinning the meter backward. That part all depends on your local utility rules and regulations.

    Grid tie is fairly easy and simple to do but unfortunately the paperwork and politics of doing it legally can be far worse to deal with in some locations!
     
  6. HarveyH42

    HarveyH42 Banned

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    Think I'll wait until get a few more panels up, considering my city's permit fees, which there probably is one for installing the panels, but neglected to check for... Figure when the carbon cap and tax comes into effect, the government will have to do something to ease the pain. Hopefully, grid tie set up will be cheaper and easier, maybe even profitable. Figure it can't hurt to get started now, least I'll have some power to work with. Demand for solar panels might drive up the price a little, and might have to wait to get them. Damn Global Warming, could really use it right now, and to think people want to slow it down, some people are just inconsiderate.
     
  7. Mr RB

    Mr RB Well-Known Member

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    Harvey, if you are already running some gear from low voltage DC, then just get a 12v DC battery power supply and control it with a solar charge controller etc so the power supply only turns on when your batteries are getting low and will stop them from getting any lower.
     
  8. HarveyH42

    HarveyH42 Banned

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    Mostly, I've been using LED lights, and recharging AA and AAA batteries, nothing heavy or important. But now I'm moving up a little, and thinking about using the power for more stuff. I wouldn't the power to drop out in the middle of brewing a pot of coffee, or lose power to my soldering iron. I haven't used an inverter yet, least not a larger one, and a little concerned that it will drain the battery quickly. I've used 100 watt inverters for fluorescent shop lights, and get pretty good use. Guess I need to just slap it all together, and see what I've got and can do with it, then figure it out from there. Probably still have a ways to go before puting the computer, TV, security video system on solar.
     
  9. smanches

    smanches New Member

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    I'm so spoiled here. Our electric company doesn't have any special fees for grid tie, and are happy to buy every watt back from you. They actually GIVE you a $1 per AC watt incentive to install grid tie systems. $2 per watt for commercial. Can't seem to find the buy-back rate at the moment though.

    Just have to fill out two applications, get a building permit for the electrical work, and then just do it.
     

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