Battery Bank Question

We have purchased a 48 volt 1 KW wind turbine. We already have 2 24 volt Solar Panels. We already have a 1500 Watt 24 volt Inverter. Is there a way to make the 48 volt turbine and the solar panels input 48 volts and still be able to use the 24 volt inverter without a lot of loss of efficiency? Or are we going to have to buy an expensive 48 volt inverter? and in that case does anyone know of a good cheaper 48 volt inverter?


  • BB.BB. Super Moderators, Administrators Posts: 32,212 admin
    Re: Battery Bank Question

    There is another thread here where "Halfcrazy" is talking about some testing he has done with a new MPPT charge controller called the "Midnight Classic" which is configured for Wind...

    Assuming it works as advertised, it would be a very worthwhile addition to your Wind system... Basically, any (good) MPPT charge controller can take Vbatt+~2volts and above (typically 135 volts or more) and very efficiently down convert it to your battery bank.

    And according to early test results for use with a Wind Turbine, you will get several times the energy harvest because of the efficient matching of the Alternator's IV curve to that of the Battery bank.

    You would still need a second solar charge controller for the panels--you cannot get around that... But it would make a very efficient system for capturing as much available RE power as possible.

    Regarding your choice of 24 or 48 volt inverters... Basically, if your using 2kWatt or less, 24 volt system is OK... If you are using 4kWatt Inverter or more, then you really will want to look at 48 VDC to keep the amps/wire gauge/fuses/breakers to a reasonable size.

    Also, if you are current using a MSW (modified square wave) Inverter--you may wish to look for a TSW (True Sine Wave) Inverter if this is for a permanent installation.

    MSW is really hard on motors and some electronic devices... Also, according to another person here, the new Energy Star Fridges use a variable speed motor and should be run with a TSW Inverter for long life.

    Take a look here for some good quality inverters and read the inverter FAQ's.

    If you have some large loads that work OK with your MSW inverter (tools, vaccum, etc.), you could keep that one connected and get a smaller TSW to run your critical loads.


    I found the post from RCinFLA regarding his recommendation regarding TSW Inverters and EnergyStar Fridges...
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Bob McGovernBob McGovern Solar Expert Posts: 25
    Re: Battery Bank Question

    MSW suffices for most applications, although a few don't like it. Compressors, or any motor that must start and run under constant load, can run very hot. This would include larger fridges, tho our small Energy Star models haven't shown any troubles. Big air compressor is grouchy -- starting up cold with under-voltage capacitors and 80 psi already in the tank. Two hp dust collector seems happy, runs cool, draws well below rated amps.

    Computers do fine; they have their own power scrubbers. Lower grade electronics sometime fritz out, like controls on washing machines or digital clocks (we had a clock that gained 10 minutes a day.:D) Most unhappy appliance I've encountered is the microwave. MSW chops off the peak voltage of the sine wine (often ~160VAC for utility power), so microwave coils don't have the same oomph. Works better if we run the coffee maker at the same time -- you can hear the nuker spool up.

    When we designed this place, available TSW inverters were too small for our system and very much more expensive than MSWs. In hindsight, I'd probably still choose MSW, simply because the wave shape has been a non-issue.
  • halfcrazyhalfcrazy Solar Expert Posts: 720 ✭✭✭
    Re: Battery Bank Question

    Yep BB beat me to it but the Midnite solar Classic controller would work for you. It will be available soon and it would convert your turbine to 24vdc for you. Plus it will harvest substantially more power for you to.
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