Many people move off grid and fall in love of the idea of free solar power.  Yes we use solar power year round and unfortunately, there are limits to it.  To come up with a reasonable answer, it really depends on three things.  1) Location, 2) Power lifestyle, and 3) System cost.  Pick any two items and it will really determine the third.

For example, choose your location and power lifestyle and that pretty much determines the number of panels and components to create that power throughout the winter. 

As described in part 1, we have a collection of various size solar panels to hook up to the new Outback FM80 solar charge controller. Last month I carefully collected data with the panels wired to produce two different voltages, 36V and 18V. While there are not a zillion data points, I was careful to keep all things the same and we do learn from the data.

18V arrangement

[ In the first part of this series, we introduce you to the MPPT technology, and to our solar array that we use to collect some comparative data.  I wrote about lost power without an MPPT solar charger in the past.   Now I have one!  Now its time tell you how it really works ]

I’ve been using and taking measurements with my solar panels and my new Outback FM80 MPPT solar controller.  This is a different animal from the older, passive, Trace C40 controller.  I have questions about this kind of charger, what voltage is best, and as I collect data to answer these questions, you will see it here first.  Unfortunately, my C40 controller was destroyed by the August lightning strikes at our home but I can calculate the gain and yoy may find my commentary on the topic useful.

Using one of the newer Multi Point Power Tracking (MPPT) solar chargers with my existing set of solar panels promises a 20-30% improvement in captured and stored solar power.  However, it does open up a series of questions