Off-Grid Wind Challenge

Greetings,

This is a problem I have been trying to solve for an off-grid customer. I am hoping that the collective wisdom here will provide me with some creative solutions.

I was brought in to look at an existing off-grid wind system that the customer was having problems with, and to talk about adding solar capacity to it. What I found was this:

- Chinese made 5 kW Air-O-Power wind turbine producing 240 Volts nominal wild AC
- Chinese made rectifier/controller charging a battery bank at 240 VDC nominal
- 40, 6 Volt lead-acid batteries wired in series to achieve 240 VDC nominal
- Chinese made "grid-tie" inverter producing 240 Volts AC from the battery bank

Based on my discussions with the customer and what I have been able to find out about the original vendor (since gone out of business), is that this system was sold as a turn-key, standalone, off-grid solution for the customer. The original vendor never actually visited the site before coming to install the system.

What I think the customer actually got was a wind grid-tie system that has been modified to operate with a battery bank in an "off-grid" configuration.

Needless to say, this customer has had multiple problems with all of the equipment and has gone as far as cannibalizing extra controllers and inverters he has on hand to keep the system running. The batteries are about the only component that are actually worth anything.

Since this customer dropped some good coin on this system, I am a bit hesitant to tell them that what they have is essentially junk and they need to start over with a proper off-grid system. However, integrating this system with a standard off-grid solar electric system is proving to be a challenge. The main hurdle (among many others) is the voltage coming from the turbine versus the battery voltage requirements for standard off-grid inverters.

Based on their projected load, I have spec'd out a Xantrex XW6048 as a replacement for their Chinese "grid-tie" inverter. In speaking with the new North American distributor/manufacturer for these wind turbines, they are suggesting taking the wind turbine output to an Aurora grid-tie inverter to produce 240 VAC constant, and then wiring that to one of the AC inputs on the XW6048. This of course begs the question of what happens once the batteries are fully charged? As well, I am not certain as to whether Power-One has obtained Canadian approval certifications for their products.

I have read all of the threads on back-feeding a battery based inverter from a GT inverter. This problem is similar, but has a bit of a different spin.

Any and all input would be appreciated.

Scott