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Thread: What to do with unused energy?

  1. #11
    Join Date
    Sep 2007
    Location
    Telford,Pa
    Posts
    738

    Default Re: What to do with unused energy?

    During the summer, RV's can get like an oven inside. Look at running a fan or two to keep the temps down.
    Ken
    Telford,Pa
    Old Homepage: http://home.comcast.net/~n3qik
    Updated 6-7-2009

    Updated Homepage: http://home.comcast.net/~n3qik/site/?/home/
    Updated 12-3-2011

    Home Automation: http://n3qik.homeip.net:5800 Password = guest
    Software/hardware is 100% complete. At least for today. Tomorrow is a different story.
    Updated 2-17-2012

  2. #12

    Default Re: What to do with unused energy?

    That's a good idea too, Ken. Thanks.
    Mage Solar Powertec 180W X 2, Rogue MPT-3024 Charge Controller, Trojan T-105 Plus X 4.

  3. #13

    Default Re: What to do with unused energy?

    The LED light has an amp limiting controller at 12v or 120v to prevent overloading the LED. The 120v units are the least expensive and I have mine plugged into a cheap 80w inverter as there is little loss in efficiency. Best to purchase the whole unit with LED heat sink. The 50w unit I have will drain approximately 35 amps from your battery in 8 hours (hopefully you have a 100 ah battery or better) 50 percent drain is about the limit on Lead Acid. The solar panels have to make up this difference on a daily basis = Two 80 w panels minimum. The suggestion of a fan is good because if the sun is out and hot then some EXTRA power can be drawn to cool the trailer. I use a Comair Rotron Model CLE2T2 as they are very quiet and energy efficient (50w) and fit in a standard RV vent and run on a cheap 80 w inverter.

  4. #14

    Default Re: What to do with unused energy?

    Enphase microinverters ought to be a good match for your panels, e.g. http://enphase.com/wp-uploads/enphas..._Datasheet.pdf. Since you already have the panels the inverters might even pay for themselves in ten years. They would require a 240 volt connector to your house; I expect you could leave the DC side connected all the time and unplug one or both to adjust how much power is available for other loads.

  5. #15

    Default Re: What to do with unused energy?

    Quote Originally Posted by dak664 View Post
    Enphase microinverters ought to be a good match for your panels, e.g. http://enphase.com/wp-uploads/enphas..._Datasheet.pdf. Since you already have the panels the inverters might even pay for themselves in ten years. They would require a 240 volt connector to your house; I expect you could leave the DC side connected all the time and unplug one or both to adjust how much power is available for other loads.
    This isn't actually relevant, as the panels are installed on an RV. He's looking to make use of the available power while the RV is parked at home (not in use). You cannot just buy some Enhase inverters, attach the panels' to the input, and back feed the grid. All GT installs must meet regulations and be permitted.

    Advocating "guerrilla install" GT systems is frowned on here as they are illegal and often unsafe.
    1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  6. #16

    Default Re: What to do with unused energy?

    I admit I am not a close follower of NEC code, but are you saying there is currently no legal way to use microinverters on RVs to backfeed a plug-in grid connection?

    As far as I can tell the existing RV plug-in (with all intervening plugs) can be used for backfeeding, as long as they are locking connector(s) and "a tool" is required for disconnect. Enphase is arguing against these restrictions for the next code iteration http://enphase.com/wp-uploads/enphas...Connectors.pdf

    No doubt there will be some clarification of the issue when plug-in cars become common, and hackerillas start tapping the revenue from their load-shifting capability.

  7. #17
    Join Date
    Mar 2006
    Location
    SF Bay Area (California)
    Posts
    21,262

    Default Re: What to do with unused energy?

    1. You need building inspector approval--There is no way you can parallel energy sources via standard plugs that do not add current to a branch circuit that is safe (or legal). You have a 15 amp branch circuit, plug in upwards of 15 amps of GT Inverters. Now that 15 amp branch circuit has 30 amps available in a short circuit.
    2. Typically Utilities are required to inspect/check for insurance/grant approval. Since there cannot be a UL/NRTL approved "plug in" GT inverter, they can never grant approval.
    3. Solar panels need to be safely attached to the roof (structural).
    4. Solar panels/GT Inverters need to be safely wired into the home/business in such a way that home wiring does not get over heated (correct sized panels/wiring) and that proper material/equipment is used (UL/NRTL approved materials).
    5. Utilities are replacing meters with ones that either do not turn backwards (you cannot get paid for your power) or even turn forward no matter which way the power flows (you actually will get charged for generating energy to the grid).
    6. Utilities are keeping track of who is generating power. In California, the utility only has to allow 1% of power to be generated by "small generators". My guess is by 10% worth of small generators, the grid will become unstable and new technologies (central control of GT inverters) would be required.
    7. As more people install GT systems--they can actually exceed the local grid's ability to handle the increase in current (flowing the "wrong" direction). Quebec is now preventing new installs for (last I read) not very clearly defined reasons (local grid capacity?).
    8. Most net metered setups do not make economic sense for the utility--Buying power back at retail and selling it again at retail just does not make sense. In California, about 1/2 the cost of power is generation, and the rest is cost of distribution, billing, repairs, running a company, etc.

    Is that to say that you placing a small 200 watt unapproved GT inverter+panel in your RV is going to blow up your corner of the world.... Not really.

    At this point, I do not see people actively time shifting power using the electric cars. It does not make economic sense because the cost of wearing out the batteries usually exceeds the savings from shifting power (at least at my TOU billing levels).

    Some countries have already made battery connected GT inverter systems illegal already (I guess, so they cannot buy cheap power at night and sell it during the day).

    Is it safe--No idea. Too many variables.

    Panel Fire Question

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

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