How long will a 12v battery last with a .0228kW drain on it?
If I have say a 800cranking amp deep cycle battery?
12v Load = 1.9A
12v x 1.9A = 22.8W = P
22.8wh
1.Add up the hours that each Load will be on for to get the Total of Energy Consumed.
2.From that you can Calculate everything you need IE: Solar Panel / Battery / Regulator

My Calculations
1 X 12V Pump @ 22.8W
on for (SEE CHART) hours per night
...................
Watt/Hour Chart
1 hour = 22.8Wh
2 hour = 45.6Wh
4 hour = 91.2Wh
8 hour = 182.4Wh
Total usage per night in Winter = 182.4Wh/d

Load and Battery 
Consumption = 182.4Wh over 8 hours
182.4 watthours divided by 12 volts = 15.2 amp hours taken from system in 1 night
Because we can only use half the energy in a lead acid battery without harming the battery,
the minimum battery size is 15.2 amps / .5 = 30.4Ah.
30% Discharge rule  the minimum battery size is 15.2 amps / .3 = 50.67Ah.
20% Discharge rule  the minimum battery size is 15.2 amps / .2 = 76Ah.
choose what calculation will be best for your battery !!
10% discharge is a non no.
I want my system to be reliable if we have four consecutive days of cloudy weather,
(using the 30% Discharge rule) 4 days of autonomy x 50.67Ah = 202.68Ah for the battery. = 210Ah + battery
(Required Battery Bank = 1 x 200 or 220 Ah True Deep Cycle

Charging Battery from Panel
This installation is in a location that gets 4 hours of full sun per day.
Check the charts for this depending on the month in the Season.
To recharge the battery for one day of use we need 50.67 amps in 4 hours = 50.67 / 4 = 12.7amps from a 12 volt solar panel array.

Solar Panel 
Most load calculations include a discount factor for the inefficiency of recharging the battery.
20% is typical. 12.7 / 0.8 = 15.83A
A 2 x 140W solar array that has an Impp (amps maximum power point) of 7.7A = 15.4A would be suitable

Charge Controller Rating in AMPS
The 2 x 140W solar array has a short circuit amp rating (Isc) of 2 x 8.2A = 16.4A
16.4A x 1.25 = 20.5A
use a 20.5A or larger charge controller with this array to charge the battery.
Cheap example  30A Unit
For best efficiency to charge use an MPPT Type.

 estimated Cost of mentioned Materials 
Have seen 2 x 140w poly panel on Net for $340 inc delivery
Have seen 220Ah Varta Leisure Battery 12V 220Ah for around $300 inc delivery
20A Charge controller $80  mppt prefered of course
Mounting Bracket for Panel = $20
Estimated Total = $640ish
Also required  Fuse box / switches / bits .. !!
Question ...If above calculations are based on a maximum of 8 hours use = 640
so 4 hours would mean 320 and 2 hours would = $160 for a 45.6W/h Load would all this calculate back nicely ?

Solar Panel specification
STK140P6A ...... manufactured by 3E
Related power
140W
Open circuit voltage Voc(V)
23V
Shortcircuit current Isc(A)
8.2A
Optimum operation voltage Vmp(V)
18.3V
Optimum operation current Imp(A)
7.7A
The above methods of calculation have all been taken from the Net over time !!
They seem to work, but if you think they are wrong then let me know.
Remember 12V Batteries should be fused and Stored in a safe manner
