Power during grid outage without batteries?

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  • tikidogtikidog Registered Users Posts: 5
    Re: Power during grid outage without batteries?

    For those who have been a tourist in India and seen well pumps run on solar, there are thousands. Most do NOT have controller and none that we saw had batteries of any kind. None of these pumps would work with batteries , directly wired to panel to pump. work everyday for years without failure. I cannot reference to these pumps in English language on Google. Nameplate instructions, Some are in French and most are in German I can not read either. IN Tahiti - they hook panels right up to a the TV and radio play all day. I did not see any controller or load center equipment. Question why is it so easy for other nations to use and adapt to solar and it is so costly for us to get going on this. Is it politics, is it our laws and rules of safety. I ask this because for example I can not get tax or income credits for any solar I put on my house because it is not a "proper house", why not put the credit advantage on the panels themselves not on the house it sits on????
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Power during grid outage without batteries?
    tikidog wrote: »
    For those who have been a tourist in India and seen well pumps run on solar, there are thousands. Most do NOT have controller and none that we saw had batteries of any kind. None of these pumps would work with batteries , directly wired to panel to pump. work everyday for years without failure. I cannot reference to these pumps in English language on Google. Nameplate instructions, Some are in French and most are in German I can not read either. IN Tahiti - they hook panels right up to a the TV and radio play all day. I did not see any controller or load center equipment. Question why is it so easy for other nations to use and adapt to solar and it is so costly for us to get going on this. Is it politics, is it our laws and rules of safety. I ask this because for example I can not get tax or income credits for any solar I put on my house because it is not a "proper house", why not put the credit advantage on the panels themselves not on the house it sits on????

    I don't think we want to be relying on what they do in India or Tahiti for standards. A quick look at their electrical infrastructure will tell you why.

    Yes there are direct-from-PV pumping systems. No batteries, but usually a linear current booster is involved.

    Direct from panels TV or radio? Not with any standard unit. Panel output is not Voltage stable so it can not be used in this manner. Chances are those are battery-based units and the PV is being used to keep the battery charged. If no charge controller is involved the batteries will be destroyed before too long.

    There's a good reason for most of the regulations we follow in North America. Safety is one thing, longevity/dependability another. Unfortunately some companies are indeed trying to stymie solar installs and they manage to get the politicians to back them either through ignorance or outright bribery.

    The tax credit is applied to households because it is meant to encourage the offset of grid demand by solar. Paying people to put PV on their RV's (or remote cabins) doesn't do this so there's no incentive to encourage it.

    It's pretty easy for people who don't understand the true complexity of the matter to either jump on the green bandwagon and say solar is the solution to all our problems right now or take the inverse point of view and say it will never work and we should stop wasting time, effort, and money on it. Both of these viewpoints are 100% wrong.
  • JohannJohann Solar Expert Posts: 245 ✭✭✭
    Photowhit said:
    Re: I found something you can use or expand on!!
    20yrDCman wrote: »
    Hmm, that's odd. They usually answer my questions fairly quickly. Give them another try for the answer. What it looks like to me is that the thermostat can handle the typical 250volts. Probably also made to handle DC pretty well.
    And to your comment about running fan and radio directly from solar, well...you could do that but because solar is higher voltage than typical 12v items would see they will most certainly run hot, fast, hard, and fryyyy. Looks like they put a lot of R&D into it and a fair amount of brains to pull it off. Could see this for RV'ers, campers, on and on.

    Through Ebay, through their web site, by phone... How many chances do you want me to give them!!!!!!!!!!!

    I actually understand how it works, the reason I specified a car radio... I'd be glad to run my O2Cool for quite a while, I've run one off an 18v battery pack to get some idea of capacity, it actually didn't seem to run hotter, but it has sorta built in cooling. ran for about 2 hours before it appeared to slow down.

    BTW-DC is a LOT different than AC, something that can handle 250 volts AC is different from DC since DC can sustain and arc. You statement is the exact reason I was asking questions. Likely since it wasn't inspected for safety they didn't want to say anything, incase someone burned down their house! Don't use AC rated breakers for DC applications!

    I still would like to run a DC direct to a heating element, using a thermostat as the 'controller' with no other and at about 175 volts... Yes, I'd like to know if they can handle 175 volts DC.

    Why not just use an inverter to power the heat element?
    The thermostat could be used to turn the inverter on and off which would power the heat elements.

  • JohannJohann Solar Expert Posts: 245 ✭✭✭
    BB. said:
    Re: I found something you can use or expand on!!

    Yep--It can work fine. He are appears to be using a DC to DC converter to take the "variable" voltage from the solar panel and down convert it to ~13 volts (stable) to run a 12 vdc to 120 VAC Inverter.

    He calls it a "relay" in the last video--It appears to be a switch mode converter. Nothing wrong with that.... And as long as the output of the solar panel exceeds the draw of the loads (i.e., 120 watt panel and 38-60 watt load), it will work fine.

    There is an issue in that this inverter latches off if the input voltage falls below 10.5 volts. He may have added a relay to "cut" 12 VDC power to allow the inverter to reset--Not sure of those details.

    -Bill
    Looks like they may use a charge controller like ebay sells. I use one like that right now for an emergency to charge my batteries since my charge controller smoked.
    Just wire it into the on-off switch of the inverter and set your on and off voltage ( higher than the shut off voltage of the inverter) then your inverter does not have to be reset.
    This controller does a lot of things, voltage off-on, time delay on-off after on or before on and many more.
  • BB.BB. Super Moderators, Administrators Posts: 31,090 admin
    A nominal water heater element in the US is usually rated at 120 VAC RMS (root mean square) for smaller water heaters, and at 240 VAC RMS for larger water heaters.

    120 VAC RMS = 120 VDC in terms of how the heating element "sees" the voltage and current (root mean square is a mathmatical term for calculating the energy in a Voltage or Current Sine Wave form back to the DC Voltage "standard").

    https://en.wikipedia.org/wiki/Root_mean_square

    Note that the "peak voltage" for 120 VAC RMS sine wave is:

    120 VAC * srt(2) = 170 Volts Peak

    And the reason for much of the caution for using DC current into an 'AC Water Heater" is that DC current is much harder to "turn on and off" without arcing. DC switches are usually much larger and more "heavy duty" than their AC counterparts.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    edited January 2016 #37

    If a switch says its rated for 125 volts AC then typically they are only used on 48 volts DC.

    Other times you can see switches rated for 24 volts DC and 250 volts AC.

    I can throw a 3 inch arc with 125 volts DC, would hate to see what 175 volts DC could do.

    I am thinking chewbacca fixing the hyper drive on the millennium falcon. 

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • asadlarik3asadlarik3 Registered Users Posts: 9 ✭✭
    edited March 2016 #38
    Use a transfer switch to transfer the pv panels from grid tie inverter input and divert them to a charge controller to charge the batteries when grid goes down. Now isolate the grid tie inverter. Then use any dc to ac inverter to supply you power. This setup will be difficult for large voltages. Batteryless is theoritical possible but not practically feasible.
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