There are various ways to do this. One way is to connect the wind turbine to a grid power inverter. Power from the turbine will be dumped back onto the grid when it exceeds what you are using (when the LEDs are off). Otherwise, it will offset the power drawn from the grid. For example, if the turbine is putting out 300W and your are using 500W, 200W of that will come from the grid and 300W from the turbine, minus losses in the system of course.
Depending on how important efficiency is and whether grid power going down is a issue, you could run the LEDs from DC with a battery. Both the turbine and the grid charge the battery as needed, but less will be automatically drawn from the grid when power comes from the tubine.
It should be possible to convert that meter to a more usable voltage range.
Generally, analog meters use a movement that is somewhere in the range of 100 uA to 1 mA full scale.
In other words, inside the meter is a resistor divider that scales the meter range to 30V, so that when 30V is applied to the terminals, there is 100 uA/1 mA of current flowing through the actual meter coil.
The meter you link to has two screws holding the terminals on the back of the meter on. It is quite likely that you can simply unscrew the back of the meter, and remove/change the scaling resistor divider.
The one exception to the 100 uA/1 mA meter rule is for direct-reading current meters, particularly for AC. Analog current meters in < 10 - 25 A range that do not specify they require an external shunt may not be possible to convert, as they use a different mechanism,
Best Answer
When one reads the data sheet, it answers some questions, and prompts others.
The output is rated at 500W in a 14m/s wind speed. In higher winds, up to its 60m/s survival speed, you may get more, depending on whether it has any controls that limit it. At lower winds speeds, down to the cut-in speed of a few m/s, you will get less, a lot less.
The output voltage is rated as 24v charging, but no wind speed is mentioned. You might expect that is also at 14m/s, at which you will be getting 500W, or around 20 amps.
What happens at higher or lower wind speeds? Is the voltage controlled to be constant, or does it vary with the wind speed? Does it have a built in charging control, that can limit the current, and to what chemistry of batteries?
Does the turbine charge at 24v? Or is it 'suitable for charging at 24v' ('when used with our optional ...')
You need to grub around on their website for more details, and if you can't find them, contact the manufacturer. If it was stated to be a simple permanent magnet generator, then it would be possible to calculate what would happen versus wind speed, at least to first order. As the '24v charging' statement implies some sort of controller in there, you need to find out what it has been designed to do, because frankly, anything the designer thought was useful could be programmed in, as long as the electrical power output doesn't exceed the wind power input ("ye canna break the laws of physics cap'n")
Bear in mind that these guys want to sell their stuff, so it's in their interest to help you use it. If they're smart, then there is already an 'applications' page on their website, showing you how it's intended to be used.