Off-Grid Solar System for the Greenhouse at Grace Ranch

By:  Steven H. Atherton

Hello again. A while back we purchased and installed a solar powered and propane heated greenhouse. Browse around or stop back for details on other aspects of this project, including the construction of our compressed earth brick power house, for this entry focuses on the solar system itself.

While we have many off-grid solar and wind generator systems at the ranch, this was our first foray into a 48 volt system. The system was designed by Wholesale Solar in California. It consisted of twelve 255 watt panels, mounted on three rows of Iron Ridge’s 3×4 ground mounted racks that feed into a power house with the following major components, together with accessories:

  • 8 Trojan L16H-AC deep cycle flooded 6 volt batteries (we sourced this locally at Continental Battery)
  • 1 Magnum 4400 watt, 48 volt inverter
  • 1 Morningstar 60 amp MPPT charge controller

A Kohler 12RES propane stand-by backup generator system was placed adjacent to the power building to provide additional power when needed, but has barely had to run over the past two years.

A couple of things to note about this system. First, we chose the Iron Ridge ground mounted racks, rather than simply mounting them to our roof as we have done in many applications, because we frequently have very strong winds at the ranch. The Iron Ridge racks are rated to 160 mph. Second, the Kohler generator model we used is specifically designed for off-grid use. Many of the standard generators that are produced are better suited to provide back up power where you have a grid tie than when you are completely off-grid. Make sure you get the right generator for your application should you decide to do something like we did. At this point, we can only report that we are pleased with our choice.

As with any solar project, time will ultimately tell about the price verses performance.   Battery maintenance, in particular, is critical if you want to keep costs down as is the function of your charge controller. The system has worked flawlessly for the past two years. We did notice that our water usage was higher than expected so we installed
water miser battery caps a few months ago and that seems to have worked as intended to reduce our water needs, which should also help preserve the batteries. Should you have any questions about our system, feel free to give us a call and ask to speak with our ranch foreman Bob as he is the most knowledgeable about how everything works.

Off-Grid Solar System for the Greenhouse at Grace Ranch