Inverters and battery need

Hello, I am setting up a wind and solar combination for my home. The wind generator is rated at 1800 watts with the option of 12/24/36/ or 48 volt output. I am thinking the 48 would be the best option to decrease the amperage on the line as much as possible at 37.5 amps max. Secondly I am building a 12 panel solar arrary in series which calculates to 216 volts, 3.5 amps and max 756 watts.

This is a grid tied system and I want to be able to expand the system down the road but don't want to break the bank on inverters. Can anyone comment on good options for inverters or wind generator voltage options etc.....must you have two different inverters, one for wind and one for solar because of the huge difference in voltage and amperage?? I noticed xantrex makes a hybrid model but it is very expensive....????

Also, with the wind generator, I have read that even though you grid tie with a 48 volt generator for example you should have the appropriate number of batteries inline before the inverter just to safely feed the inverter without risk of huge spikes in power etc...is this advisable or a waste of money....I don't want the batteries or really store power as our house uses a lot of power....my goal is simply to feed the grid and offset our current bill as much as possible.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need

    brenneis,

    This and a couple other threads you have started are currently stuck in the "Moderation Queue". I messed up and moved them to the appropriate sub-forums before I "Approved" the posts--so now the BBS software is a bit confused--hopefully, they will be fixed in the next day or so.

    By the way, please select the appropriate sub-forum (Wind, Off-Grid, etc.) forum instead of the web-site announcement forum (which is for Admin announcements only).

    Regarding your questions--It is not an easy answer--but I will try:

    If your system is a pure Grid Tied Inverter type (no batteries)--the PV panel voltage will be in the ~200-600 VDC range.

    If your system is using standard off-grid inverter (12, 24, 48 vdc, etc.)--they cannot be connected directly to the utility grid without lots of excitement (smoke, fire, death, etc.).

    You can connect off-grid inverter "to the grid" only as a UPS type installation (AC input to charge battery, provide bypass AC power to load, auto switch if grid fail to battery AC inverter to load). Some of these inverters also provide AC Generator inputs (chargers, AC bypass)--But again, these setups can only power your AC loads--they cannot back-feed AC utility mains (either safely or legally).

    There are Hybrid GT/Off-Grid inverter systems out there that combine the some of the best of both types of systems... Efficiency of GT, and emergency power of off-grid for emergency backup... However, they are not cheap and still require significant battery banks for proper operation (see Xantrex XW system for a good example).

    There are regulatory issues with Grid Tied systems--one of which is that you cannot legally (or safely) build your own solar panels to attach to the GT inverter to provide power to your utility (net metering--turn your meter backwards). Most places in the US require building permits, inspections, and usually some sort of utility approval and insurance--something that home make solar panels cannot ever be approved for.

    Also, typically, GT inverters tend to be rather large to get a good price point... Typically, ~3kWatt of solar panels is a good starting point. 800 watt GT inverter/system is pretty small.

    If your needs are to setup Net Metering with Solar PV GT inverters and not have emergency backup power--then a standard GT inverter is the way to go (no batteries). Cheapest and most reliable system, little maintenance, and least amount of hassles.

    If, you want to add wind--you have several choices... One is to find a wind turbine that is a native GT device (such as this one).

    Or, you would have to use a Xantrex XW type system (Outback may have something available too) that allows you to connect a DC wind turbine to a battery bank, then the battery bank to a GT type Inverter (designed for connection to a battery bank).

    The above will work (and you could connect a Generator that "charges" the DC Battery bank--and power the grid through your GT inverter too).

    However--again, lots of issues. The "typical" DC battery Bank GT inverter is 48 VDC. Many wind turbines require something like 20-25 MPH winds before they can generate any significant current at 48 VDC (the new Midnite Solar wind MPPT charge controller that may be out in a few months may "fix" this issue somewhat).

    And, unless you have "cheap" fuel and very expensive electric rates--the amount of money you "get" from the utility will almost always be less than your costs for fuel and maintenance for your generator.

    Lets slow down a bit here... You are placing the cart before the horse and this will probably waste a lot of your money.

    You need to understand your utility's net metering policies (not all are equal), your utility rates, and your costs for power generation...

    Just as a very rough idea...

    $0.10-$0.30 per kWhr for utility power
    $0.10-$0.30 per kWhr cost for GT power (after government rebates)
    $0.50-$1.00+ per kWhr for Hybrid GT/Off-Grid power (i.e., Xantrex XW system)
    $0.50-$1.00+ per kWhr for generator fuel costs
    $1.00-$2.00+ per kWhr for Off-Grid power

    In the end--even though this web forum is owned and supplied for our use by a company that retails/wholesales Solar RE equipment (NAWS--Northern Arizona Wind and Sun)--we all recommend that every potential Solar RE equipment/system purchaser work like heck towards conservation in their own daily power consumption (insulation, energy star appliances, turning things off, passive solar, solar hot water, etc.) before even beginning to look at generating your own solar power.

    In generate--it is much cheaper to conserve a kilowatt of electricity than to generate it.

    If you have not yet--get a kill-a-watt meter and start measuring your own power usage (120 VAC, 15amp max. with kill-a-watt meter):

    wind-sun_2050_2425819Kill-A-Watt AC Power Monitor Meter
    P4400 Cumulative Killowatt-Hour Monitor

    -Bill

    PS: And I will continue to see if I can get your other two threads restored (I am only a Moderator/Spam helper here--not the Admin)... -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    ok, thanks.....I have looked at the sonny box and xantrax grid tied inverter for the solar portion. As to the wind since I am looking at an inexpensive 12V wind turbine that will be mounted on the roof of our shed right at the ridge of hill line so it gets really nice updrafts....I really don't want to deal with a large pole installation and am really just putting it in for to play with....business is really slow right now with the economy and I got too much time on my hands....lol...since we use way more power than I can produce right now for any type of net metering to (turn the meter backwards)....can't I just connect the wind turbine to a 12V battery with a charge controller and then connect the battery to a small pure sign inverter and connect to my AC panel.
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Inverters and battery need

    ".can't I just connect the wind turbine to a 12V battery with a charge controller and then connect the battery to a small pure sign inverter and connect to my AC panel."

    Danger, Danger Will Robinson!!! You can't do this is your AC panel is tied to the grid. Tying in a non-rated, no authorized inverter to your AC panel is a recipe for disaster,, at least a life safety hazard.

    Please read up on grid tie inverters,,, and how they work. In short, they are designed to shut down in the event that the grid goes down. This exists as a HUGE safety issue,, both for you and the utility!

    Tony
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Inverters and battery need

    brennels,
    please, please, if you have that much time on your hands, read up on this stuff as not all inverters can feed the grid. if they aren't specifying they are grid tied then at a minimum you will destroy the inverter and the damages and possible bodily harm too can go up from there.
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    I know this niel..I have been reading up on them for weeks. I understand that a grid tie inverter must be a "grid tie inverter" with either a DC auto shutoff built in or a separate one built in line.

    My comment was meant to say that most of my system is solar which requires high voltage inverter low amperage....looking at Xantrex and sonny boy pure sign drid tie inverters.

    I am also looking at smaller pure sign grid tie inverters for a small wind turbine. Preferably I would love to have one inverter that could take both high solar voltage and low wind voltage but they seem hard to find. They are mostly all 12 volt and intended to draw from battery banks.

    MY question was primarily if you don't care about storing energy and want to feed your house and you have a 12 volt say 300 watt wind turbine grid tied with a charge controller and quality pure sign inverter is that ok to maximize net metering. Ie. if battery is full do the systems automatically send to the grid. and if battery gets too low since I only have one will it still discharge and charge properly. Dealing with lower cost pure sign inverters and wind turbines this seems the way to go. Please don't worry, my neighbor is a licensed electricion and I would never connect anything without thorough inspection first. I have a pretty good grasp of most just trying to figure out options on a budget.
  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need

    brenneis,

    As you have read my various posts--I personally do not believe that wind turbines for home sized designs are very cost effective/reliable.

    And cost wise--from my little looking around and reading--typically cost effective Grid Tied systems start around 3,000 capacity. The components for a 300 watt capacity system are 2+ times more expensive for the components.

    Lastly, the typical small horizontal axis wind turbine needs special consideration when installing... Usually a "dump" load is required so that the turbine will not over-speed (and fly apart) in windy conditions... Solar panels do not need anything like this--you can "turn off" the output of a solar panel in sunlight without any issues.

    I believe there is a 600 watt "Windy Boy" GT inverter out there--but hour host (NAWS/Windsun) has said before that it was never available (or at least reliably available) for sale from the manufacturer.

    There is now a small, UL Listed, ~200 watt solar GT inverter for solar panels:

    wind-sun_2049_1019373Enphase Micro-inverter Grid-Tie Systems

    But--I don't believe it will work/be safe for wind.

    In the end--at this point you would be better to either build a full sized Hybrid system (Xantrex XW or equivalent) and use your DC sources to charge the battery bank for GT sales...

    And/or simply build a small DC wind turbine system (or just place a recording device on a pole) to get hands-on experience and re-visit your GT Wind question in a year or two after you have gathered data for your site. And, given that there is a DC battery bank for this wind sytem--you could also add a few solar panels and charge controller to the same bank and compare operations and results for both types of energy collection types.


    I don't think that there is anything out there at this time that would supply you any meaningful and safe amount of AC Net Metered power, as a GT battery less connected 300 watt wind turbine... (in my humble opinion--and I may very well be proved wrong here :cool: ).

    I think someone else here supplied a link with www.otherpower.com ... That would probably be your best "home brew" wind turbine forum to start wondering through.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    what about small wind turbines that have a built in inverter to AC

    check out

    The WindBlue DC-540 Permanent Magnet Alternator PMA equipped with 3-phase AC and standard DC output connections. Note: "AC Output Connection Kit" required for use with the 3-phase AC Output connector. (sold separately)
    TLG Windpower Products NEW 5 Foot 4 inch Diameter "Cy-Clone" Rotor Blades perfectly match our generators providing increased performance in high wind situations while still maintaining great low wind performance.
    Custom Built Yaw Mount Assembly with Exclusive Teflon Pivot Washer
    Laser Cut Aluminum Tail Vanes which match the Rotor Blades Perfectly and Create a Super Cool Look
    This is The Highest Quality PMA Wind Generator Kit around. Built with the Best Components at an Affordable Price
    Complete Assembled Weight: 34 lbs
    Overall Length 43"
    Generator Features:


    Completely Brushless Alternator eliminates the need for maintenance and reduces friction
    NEW !! Now equipped with a 3-phase AC Output pigtail. This small black connector on the back of the unit allows you to run less costly 3-conductor wire to your battery location instead of large heavy battery cables. Once at the battery location the 3-phase AC is fed into a rectifier box (sold separately) and converted to DC for connection to the battery.

    Note: WindBlue AC output equipped alternators can still be connected for DC output by using the battery terminal on the back of alternator, however, only one output should be connected to your batteries at a time. The other should be left unconnected.
    WARNING: The 3-phase AC output connector DOES NOT make your alternator a “Grid-Tie” unit so don’t try to wire the AC leads into the fuse box of your house as death, fire, and destruction will likely result !!
    Specially wound Low RPM Output stator.
    Super Strong N42 grade Neodymium rare earth magnets in its core to replace the inefficient electromagnetic field coil
    Zero Cogging
    It is built using Brand New GM Delco alternator components including NEW Stator Coils, factory balanced shafts and New Rotor Pole Shoes. Replacement bearings and parts will be available for years


    they seem like a good company and the price is right and they are right upfront with warning about connecting the AC outputs to your house of course....my question is has anyone heard of a rectifier or something like that which would regulate and take AC power directly for the small wind generator and turn it in to pure sign for grid tie....are is it only AC to DC to charge controller to batteries to pure sign inverter. Latter seems like a pain in the butt to make it worth it...if they have the former it could be kind of cool.
  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need
    brenneis wrote: »
    WARNING: The 3-phase AC output connector DOES NOT make your alternator a “Grid-Tie” unit so don’t try to wire the AC leads into the fuse box of your house as death, fire, and destruction will likely result !!

    Alternators on Wind Turbines (and in cars/trucks/boats/etc.) are really three phase alternators--They are very similar to three phase synchronous motors.

    However--their output frequency is dependent on their rotational speed--and, I would bet, are running at a much higher frequency than 60Hz (my guess; typically around 100-400 Hz).

    These "generators" are called "wild frequency" sources... Their frequency varies with the wind speed, load, and other issues. There is no way of directly connecting one of these to your 50/60Hz utility feed.

    Now, these types of alternators can be used in some very nice equipment... A Honda eu2000i inverter/generator is an example. The Alternator frequency/voltage varies with engine speed (ECO Throttle cuts back engine RPM to save fuel for low wattage loads) -- but there is an internal AC to AC inverter internally that converts the alternator's varying output into a rock solid 120 VAC 60Hz output (with the ability to parallel two genset together).

    Regarding the vendor you have listed... Go ahead and try one of their units. They are not expensive and you will learn a lot from running one.

    If you expect to get a significant amount of energy from such an installation or have it run 10 years without maintenance--I would not bet my first born on it.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    thanks bill, I read the warning and it no way would connect that to my panel....I can't find voltage regulators that take wild AC and turn it into Pure sign AC...if you guys sell one, I want it...... it seems that would make much more sense then going from AC to run small cord over long distance to rectifier for DC to battery charge controller to batteries to pure sign inverter........it would be much simpler just to take the wild AC and regulate it like the generator you mentioned.....can that be done...
  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need

    The short answer is that it is not done because, even though it could be done, it is very costly to do this...

    Imagine you need to run a 100 watt AC load. You plug in a 100 watt solar panel to the magic black box... Turn on your 100 watt load, you find that the solar panel+black box only run at 77% efficiency.

    Put 100 watt / 77% = 130 watts of solar panel on.

    Now, turn on your load--AC power collapses and load won't start because it needs 200% starting current power for a 1/2 second.

    OK, take the 130 watts * 2 = 260 watts of solar panels.

    You find that the load starts and runs from 9am-3pm nicely. Except, a bird flew by, a cloud came in, etc... load cuts out, inverter resets, load resets, may start, inverter may "brown out" and burn out the motor windings, etc...

    So--you are left trying to define the load better... Pick a lower power application whose load can vary with the available voltage/current. A DC powered water pump works very nicely for this application. Lots of water at noon--cuts back off peak times and in cloudy weather. You are filling the tank so you can pull water at your schedule--not when the sun is available.

    The reason it works for the Honda euX000i is because the gas engine has additional power available if their is a demand made for additional current from the alternator/inverter... Solar has no such function.

    Anyway--that is my two cents worth of reasoning.

    You could purchase a small Honda/Yamaha/knock-off inverter generator and pull it apart and see what make it work. You might even find a used genset (working but blowing smoke) and make a real project out of it.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    but if it were grid tied then the grid would be there for any load needs....I just wanted to convert the wild AC from the small wind turbine in pure sign so I can tie to the grid..then whatever it can give me to offset my bill so be it.....is that still not possible....

    one other question which might be stupid but I will ask it anyway. As I understand it on a solar cell..the top is positive and the bottom is negative. I took one of my cells out in the sun and connected the positive red lead on the multimeter to the top wire and the black to the underside of the cell and it read - .56 volts....when I flipped them around it said +.56 volts...why in the world would it read negative when positive was connected to the top and negative to the bottom...
  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need

    The only "small" wind turbine that I know of that can converter wind energy directly to Grid Tie AC is the Skystream.

    It has been out for a while--and has had mixed reports of operational capabilities. You might try reading this blog as a start about how well it works.

    If I recall correctly, the purchaser of a SkyStream (a few years ago) was having issues with trying to get his system working. Started the Blog to complain--and eventually the company hired him (?) for some of his computer expertise (don't know the details) and helped him with his system.

    There were lots of reliability and operability issues with the Skystream--I guess they have fixed some of them over the years--but issues still exist.

    I am not a big wind fan--so I would not recommend you purchase a Skystream--but you might find some use/parts systems out there and do some further research.

    But I doubt that you will find a small, cost effective, GT inverter for wind.

    Here is a 700 watt "Windy Boy" GT inverter from SMA. They make good products in general. Searching the Web shows them ~$1,200 to $1,400 each--which in a larger system should be rated around 2,400-2,800 watts of capability for the price. (~$2 per watt for this small Wind GT inverter vs ~$0.50 a watt for larger GT inverters).

    You will have to call around to see if you can find a place that stocks this unit (I have no connection with NAWS or any other solar store/vendor--so I cannot help you there). But, if you have the correct Wind Turbine design--this should be a very nice/safe and legal unit for your GT / Net Metering use.

    :confused:

    Regarding the solar cells--just what I have read there are either mistakes in some popular graphic used across multiple websites (one shows "P" material on top, and a paragraph below, shows "N" material on top. May also depend on what type of cell (silicon vs thin film) or other issues... But in any case, if your meter polarity is correct--the average cell should not "inverter" polarity--so there is some other issue.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    do you have any idea as to the negative voltage reading per my other question below?? I am at a loss...again probably stupid but it has me stumped...thanks for all your time..
  • BB.BB. Super Moderators, Administrators Posts: 32,316 admin
    Re: Inverters and battery need

    I have not studied the solar cell in detail to know which terminal is negative or positive...

    But Googling around, I have found the drawings here copied on several other "how things work sites"...

    Near the bottom of the page--there is one drawing with sun "shining through" the top "P" layer. But a page down, is another showing the stackup of a solar panel array--and they have the negative terminal on top. According to that drawing, the negative terminal is on top. :confused:

    Double check your volt meter's polarity with a 1.5 volt battery--but for whatever reason, the cell's polarity is the opposite of what you think it is.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    ok, I am also checking with the manufacturer....as far as I can tell I put a perfect panel together...40 cells that averaged out to be 22 volts and 3.5 amps :-) same thing as the individual cell....positive on bottom and negative on top....glad to hear you say you found others where negative is on top.
  • brenneisbrenneis Solar Expert Posts: 34
    Re: Inverters and battery need

    problem solved, I didn't do anything wrong, it works find...negative is just on top on these cells....40 cells putting out 23 volts today and 3.6 amps....
Sign In or Register to comment.