Charge Controller for Solar Power System, $50
This unit costs $202, including tax, at Amazon.com.
Amazon Blurb:
The NC25A Beats all other charge controllers for efficiency
Has the highest rated Max Input Voltage of all controllers in its class 140 V DC
Handles up to 25 Amps of DC Current into a 12 Volt Lead Acid Battery (Approx. 300 Watts)
Adjustable charge threshold lets you optimize charge voltage for your output
Industrial metal case - hardened for outside weather.