"You have solar panels! You must always have power!"

[papaof2]

Only if we have sun. The MPPT charge controllers are programmed to do a 2 hour equalization charge on the 28th of each month. Today is the 30th and is the third day in a row of clouds/rain. The laptop monitoring the charge controllers still has "Equalization Charge" in the "Battery Status" field. The reason is pretty obvious if you look at the ouput from the solar panels: 200 watt panel is 1.3 watts, 100 watt panel is 0.55 watt. That's on the order of 1/2 of 1% of the rated power of the panels. Solar power is totally dependent on the amount of sun. The 2 hour equalization charge is in its third day because there's not been enough sun for the solar panels to get the battery bank to 14.4 volts for 2 hours - in fact, the battery bank hasn't even reached 14.4 volts these three days.

That problem is being resolved as I write this. There's an adjustable 16 volt power supply (think - one solar panel) which can be switched in place of the solar input to one charge controller. Today, that power supply is set for 3 amps so almost 50 watts of "solar" power. The power supply can go up to 20 amps, so why limit it to 3? The 3 amp charge takes longer, so the battery has time to absorb a full charge and not just quickly reach 14.4 volts and have the charge controller cut off. It's the little things that make the batteries last longer.

[papaof2]

The controller decided it had charged the battery bank long enough at 14.4 volts and it shut down about 1:15PM. I switched the controller back to the solar panels. Nice to be able to monitor the Win 7 laptop remotely using the free UltraViewer.

[9idrr]

Nice to read about real world usage, as opposed to manufacturers "specs" that one is supposed to believe.

[papaof2]

There's a site that can give you the effective sun hours each month, based on your location and the angle of the solar panels. www.solarelectricityhandbook.com/solar-irradiance.aspx

It says that we get 3.96 hours in February but my tested number is 3.2 hours (running 800 watts of solar panels and enough load to keep the battery bank in the range of 85-90% charged). If I use that number and the NOCT rating of the solar panels (73% of the label (STC) rating), I won't be disappointed by the solar power I wind up with. My spreadsheet has a lot of that type pessimism, but it shouldn't leave you in the dark ;-) Much of the spreadsheet has fields for both STC and NOCT ratings, but I design things for my use using the NOCT numbers.