So why watts instead of amps in figuring the power requirements? Basic question, but I monitor my consumption and charge in amp hr (link pro monitor).
Good question.
Hrmm...
In visualizing electrical systems, it's sometimes handy to use a compressed air analogy.
Watts would be the basic unit - like cubic feet.
Amperes would be a flow rate - like cubic feet per minute.
Volts would be pressure - like 12 psi.
So what I did was figure out the number of cubic feet we'd use, and thus how many we'd need to put back. And then how many CFM the compressor would need to supply to get it done in 4 hours.
The problem with specifying amperes, is that it's meaningless without ALSO specifying voltage.
Let's say we pull 1200 watts out, over a period of 10 hours. That's 120w/hour.
If the system were at 12v pressure, that would be 10 amps per hour flowrate.
If the system were at 24v pressure then the same 120w/hr would be a 5a per hour flowrate.
So it's not exactly "technically" correct to say something like, "We used 100 amp*hours".
Technically, it should be stated, "We used 100 amp*hours
at 12 volts".
Or, we could say, "We used 50 amp*hours
at 24 volts".
Either way, we'd be saying the same thing, "We used 1200 watts". [EDIT: Woops. Should say, "We used 1200 watt*hours".]
For estimating solar, there are many different ways to do the rigging.
You could have two "12v nominal" solar panels in parallel feeding into a pair of "12v nominal" batteries rigged in parallel into a 12v nominal bank.
Or you could rig the panels in series, and also rig the batteries in series, and have "24v nominal" on both sides.
Or you could rig the panels in series to have 24 nominal on the PV side, and feed through an MPPT controller to a 12v nominal rigging on the battery side.
Each different sort of rigging is going to end up with different voltages and thus different amp*hours numbers.
But the watts won't change no matter how you rig it, so it's just a lot easier to do the ballparking in watts.