My Alt-Power Setup Diagram


I never intended to build an off-grid setup.  I'm in hurricane prone Florida, and power outages are a way of life here, whether it be due to a hurricane, tropical storm, or just another severe thunderstorm.  I started with a single battery, and a basic inverter, to run some lights, fan, and a small TV.  Things slowly progressed, and I added a generator.  Eventually I added a number of batteries, and a few solar panels.  From there, it's grown to what you see below.

The difference between my setup, and a system owned by someone with money, is mine has been pieced together, rather than buying a complete system, and having a couple of pros put it together.  This is why there are two charge controllers (so far), rather than one larger one.  Turns out MorningStar, the manufacturer of both of these models, says they can be paralleled without issues, but must have their own separate solar panels to regulate.  They were right.  Each controller does exactly what it was intended to do, and doesn't cause issues with the other.

The drawing below gives a good overview of how things are wired.  There are some details omitted to prevent this from being overly complicated.  There are two small inverters used for lighting circuits, and due to the low power consumption, they have been connected to the DC Distribution Panel shown.  All the DC loads are also connected to this panel, and are not shown.


The full sized PDF file is here: Link


The Master Switch turns off all the loads, but not the charge controllers.  This allows me to work on things downstream safely, without having the charge controllers going "stupid".  These controllers require a connection to the battery FIRST, to power up the microprocessors within the controllers.  If the battery connections are disconnected, while still being connected to the solar array, the controllers will squawk and flash LEDs.  The array must then be disconnected from the charge controllers, wait a minute, then connect the battery connections to the charge controllers, then the array once again.  PITA.  So right or wrong, this is why things are wired as they are.  Everything is fused to protect the wiring.  The battery charger has two external built-in fuses not shown above.

The 175 Amp Master Fuse has also been downsized a bit.  I don't run the Prosine inverter near its max rating, and the DC loads are light.  One thing to note about these fuses I'm using is they aren't instantaneous.  It takes a significant overload for the fuse to blow quickly.  Otherwise it could take minutes to finally blow.  I have a couple of spares, plus a couple of larger spares if I find this to be too small.  But over a year of use, I rarely go over 100 Amps.  I'd rather have the external fuse blow, than have one in the inverter go.

So how much current does this setup provide?

A tad over 29 Amps during the peak of the day.  Measuring the current from both charge controllers at once.  I expect to get close to 36 Amps during ideal conditions, when the weather is cooler. 

620 Watts * 70% (derating factor) / 12V = 36 Amps.  I have one 30 Amp controller, and one 10 Amp one.  Just about near their limit.  I'll have to add yet another controller when the system is upgraded once again.  Hmmm, 45 Amp controller next time?



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Last updated 09/13/09    All rights reserved.