Solar panel Notes:
Optimum angle for solar
Fixed--~30
Degrees
Two season
Summer
(march 30-september 12th)- ~8 degrees
Winter
(rest of year ~45 degrees).
Sites:
Note, angle for grid-tie is very different than
off-grid. (because you are watching for
optimal energy generation the whole day.
For the mini off-grid installations, current position is
good for winter (until march 30), lay on top during summer.
Batteries for mini-grid
System works for either 12 or 24 volt battery systems
(however, you need different output systems for 24v) For simplicity, I recommend all small systems
stay at 12v.
You can use 2 6v batteries in series to get 12v, but they
must be very very similar.
Checkout of Battery
Battery checkout is the most dangerous step. It is a little safer to do battery checkout
with a smart charger (from 110), but it can be tricky in other ways. (I had fully discharged batteries take days
to recover on a charger, but I think the charge controller would have quickly
worked).
Do not attach a battery directly to an array of
batteries. (Even a good battery could
rapidly charge, generating hydrogen, and explode, spraying sulfuric acid.) Battery testing should be done outside. Batteries should always be on a thermal
insulator (like a piece of wood). Lead-acid
Batteries are not really a fire risk.
(all types of lithium batteries are a fire risk because they have ~10x
energy density).
The Charge controller to battery hookup has clips for this
reason.
#1 measure new battery voltage (should be between 9 and 12
volts, but not necessary).
#2 remove clips from existing batteries and attach to new
battery (battery should be at least 30#s).
#3 measure new battery voltage (do this during the day). Within 10 min battery should be between 9 and
12 volts. If battery is not quickly
moving to 9 volts you may have a problem.
#4 Everything should work right away, but avoid placing heavy
loads, and night use
#5 Every evening and morning check the battery voltage to get
a feel for self-discharge and capacity.
Loads
The charge controller is a 42v 30A device.
That means that if any circuit goes over 42v and/or 30A, at
least that part and likely everything fails.
So voltage open circuit (VOC) of the solar panels should be
less than 42 volts.
