No mate I am not going to get into an argument with you or try to prove you wrong , the time and effort you put into helping people is far to valuable.
There is nothing personal in my posts just a different opinion so if you don't mind keep the personal comments to yourself.
Anyway I have 2800W of Panels 14 x 200W Panels , according to your calculations how much power did I generate today ?
As far as consumption and setup to run the average laptop , not sure what you have but those usage figures are very conservative.
What laptop could be run from a 12 or 13volt system anyway ?
A 12 volt Gell or AGM needs a charging voltage around 14.4 Volts , so you are going to need a proper MPP regulator / Charger to keep any decent battery working for any length of time. , While you can maintain the 12 Volt battery this way you are not going to be able to supply the average laptop with the needed 18~21volts most require from a single 12volt battery.
A 24 Volt supply stepped down the 18~21 volts you need would be ideal , so you would need to 24V battery bank.
The original Poster said his laptop is 19.5 Volts and asked about a 24Volt Solar system so he had the right idea.
A 30W panel puts out around 18 volts, while this is enough to charge the 12 volt system it's not going to supply enough voltage to charge the 24 Volt batteries so you either put 2 panels in series or a single larger panel ( why I suggested the 120W ) because it can output 31~36 Volts OC , enough to supply a 24Volt MPP charger / Regulator to charge our battery bank.
I use a Dell Laptop that requires 19.5V charging at very minimum 1.5amps or it reports wrong charger message ., using it without all the power saver options it can be stretched to run for 2 hours so it uses 28WH ( 56WH Battery), The laptop battery voltage is irrelevant in the equation.
So it needs a minimum 168WH for 6 hours running without allowing for dead flat Charging / Usage at the same time and without allowing for any loses that as you would know are always present .
So 7AH from the 24V Battery over 6 hours , I would round this off to at least 10 AH allowing for loses , now we want to allow for maximum 50% DOD so we need a 20AH battery , Using my first example I am not cutting to the bone I am being liberal so a 60AH battery bank is only going to last for 18 hours running without a recharge , not much redundancy really and will still run perfectly during the raining and full cloud days , as we both know these can sometimes be weeks at a time.
As for how much you can get from a 120W panel per day , I only ever calculate worse case scenario's and I know from a lot of playing around with panels that some days you can only get an hours worth of total production , EG: I have got 82WH production from an 80W panel over the entire day., but early summer have produced 515WH for the day from the same panel.
Just for interest sake I have a full Haze Gel battery bank 720AH@48V 864KG's + all sorts of different Deep Cycle batteries I use for experimenting , Also running the new state of the Art SMA SBU5000 full home backup system.
It's all fun
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