How do solar hybrid light units work?

All our units work in the same way:

1) The sun charges the batteries during the daytime

2) At dusk the LED lights come on. This can be automatically done with the on-board light sensor.

 3) The unit  operates through the night off the battery bank.  Every few hours, the engine generator will come on to top the battery up.  

4) Maximum night time engine use is only 4 hours over a 10 hour night, resulting in less engine wear, less noise and less fuel consumption. 

Why not use full solar power?

There are several issues with full solar light towers: 

1) You need at least 3m2 of solar panels on a  small trailer to generate enough power to charge the batteries within a full day of bright sunshine. That's a huge area.

2) If you have overcast conditions for a couple of days; the battery bank will drain dry and you'll have to take it out of service to recharge (ironically by connecting to mains power or a diesel generator)

3) Even with daily sunshine, the battery bank will totally deplete with current solar-only units over a period of time. This is because the