ASK THE EXPERTS: Grid-Tied Wind with Battery Backup

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I am searching for information about a grid tied wind-electric system that also has battery backup. There doesn’t seem to be a lot of information out there on this particular setup. Have you heard of people doing this?

Zac Luhellier • via email

Any battery-charging wind generator can be part of a grid-tied battery-backup system, and this is very common. Models that show 48 volts as an option will be best for a modern North American home.

Perhaps you are already familiar with batteryless grid-tied systems, which couple a specific wind generator to a specific inverter—the two must be matched. Only a handful of wind generator manufacturers have done the design work to customize a specific inverter to work safely and effectively with their wind generators. Batteryless wind is definitely not a situation where you can buy a wind turbine and then go shopping for an inverter. You should buy the two together, from a reputable source.

But you asked about battery-based grid-tied systems, which is a very different situation. In that case, the charging source is not directly matched to the inverter. It simply charges a battery bank. You’ll want to size your battery bank for your backup needs, and make sure the charge controller for your charging source has an output voltage compatible with your battery bank.

The inverter in a battery-based grid-tied system is not directly coupled or matched to the charging sources. It only needs to be large enough to handle the total charging wattage of your sources, so it will be able to send excess energy back to the grid even in times of peak production. The inverter, of course, also needs to be able to have the capacity to run all the backup loads you might want on at one time (see “Sizing a Battery-Based Inverter”).

You could have multiple charging sources putting energy into the battery bank and one inverter selling to the grid. You could also have one charging source and multiple inverters selling to the grid. The specific configuration will depend on your situation.

Batteryless systems require expertise and education to design and install; battery-based systems need even more of both, since these systems and their electronics can be quite complex. Work with an experienced designer and installer to get what you want.

Ian WoofendenHome Power senior editor

Comments (4)

ideas2014's picture

dear Guys and experts
i have question may leads us to debate i hop any one with good understanding & experience in wind energy can give me good productive answer ,,
we all know that the new interactive BB grid tie inverter has 2 AC input , one usually used for gird and the second one used for Diesel generator as standbye power supply ...in case no wind or no grid .
here i want suggest new option , which i hop we can share opinions and solutions ...
i want use the main AC input relaying on my turbine PM generator which generates 230 AC 10 KW and will use the other AC input for the grid ,,incase my wind power supply fails for any reason i can relay on the grid immediatly
thru this way i will avoid the losses from the power generation source from the wind generator thru charge controler , charging batteries and then inverter ,,or even using DC from my wind PM genetaor thru rectifier to convert the AC to DC to feed the battery

i think this model can work with outback power and SMA ..i wish tio this wrong , possible or not ,,,better or not

what or how u see guys this suggestion ? am i crazy or stupid ,,,thanx for sharing
thanx

BlindSquirl's picture

The simple answer is that it is cost prohibitive.

In most cases, grid electricity is much cheaper than installing a wind generator. i.e. you will pay a lot more to keep your batteries charged with wind than you will to keep a float charger plugged into an outlet.

You will never recoup the cost of your investment.

Ian Woofenden's picture

Simple answers don't always convey the context and complexity.

Cars are cost prohibitive. Houses are cost prohibitive. Trips to Europe are cost prohibitive.

People do things for many reasons, and cost/return are not always high on the list.

Also, the situation a person is in has a high impact on the financial calculations. Off-grid in an area with great winter winds and not much winter sun is very very different from on-grid in a place with a good solar resource and a poor wind resource. A location that requires 180-foot towers to get into the good wind is very different from a location in the plains or by the ocean where an 80-foot tower may be adequate.

"Never" is a long time from now, and it also assumes that you only value dollars, not security, the environment, socialized costs, and who your utility is inflicting damage on -- future generations, ecosystems, etc.

My conclusion -- after dealing with many readers, students, and clients -- is that every person has different motivations and a different situation, so many different choices are made. What may be "cost prohibitive" to one person is the fulfillment of a lifetime dream or the most reliable power supply to another.

Ian Woofenden, Home Power senior editor

ideas2014's picture

really great article ,,even i read late but still very useful
does any one can recommend me a reliable consultant for BB inverter system design .. i am based in singapore

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