i am fully a ware of how to calculate and install solar system for home uses ....we first start by determing our loads in hour fashion
for example one lamp 100 watt for 10 hours means 1000 watt /hour amount of energy is needed
which means that we need battery that hold this amount of power which will be 1000/12 that is 83 amper battery doubling its capacity wont harm since this wont allow battery to
be "completely discharge"
83*2=160 amper 12 volt battery
160*12=around 2000 watt
now comes the tricky part ...the panel ....we have got 2000 watt ...that needed to be collected ....hopefully in one hour ...but that is impossible because 2000 watt panel will produce large currents that will destroy the battery
many suggest the "GOLDEN RATE " of c/10 where c is battery capacity now we do have 160 amper battery /10 that is 16 amper
so we have to buy that panel that gives 12 volt at 16 amper and we have achieved that "golden rate"
panels that charge 12 volt batteries are not 12 volt panles ...they are 18 volt vmp panels .....vmp is the maximum power voltage ..
so we need 18vmp panel at 16 amper ....despite the fact that 18 panel @16 amper panel is a 290 watt panel ...but because we use a pwm controller in this design
18volt @16 amper is never a 290 ...because pwm controller will only use 13.5 at 16 a and toss the extra voltage
which will "DRAW' only 216 watt out of 290 watt panel ....
even designing this system with mppt is ok .. that will allow us to buy panel that has 18 volt at lower current than 16 ...
the extra lost voltages that pwm tosses mppt convert to current and thus
we wont lose money by buying large panel that we only draw little watt out of it
...sorry for this long prelude but in a nutshell by following "solar bibles" we find our self with a
SOLAR PANEL THAT HAS POWER RATING THAT IS 1/10 OF THE BATTERY WATT
IN our case 2000 watt battery (12 volt *160) and the panel is 290 watt (from which we get only 216 watt due to pwm controller) or 200 watt panel
18 at 11 amper panel if we use mppt ....despite the fact that the mppt will charge battery at 13.5 but turn the lost voltage into current
which will crank up current into 16 amper again
so how some system manage to charge batteries in 4 hours time if we follow the rules we only find our self with panel that 1/10
of battery wattage which will force the harsh fact that our panels will collect our needed power in 10 hours time
very very long and perfectly impractical even in the middle east countries (libyan man here )
thanks every body please share your thought with me
for example one lamp 100 watt for 10 hours means 1000 watt /hour amount of energy is needed
which means that we need battery that hold this amount of power which will be 1000/12 that is 83 amper battery doubling its capacity wont harm since this wont allow battery to
be "completely discharge"
83*2=160 amper 12 volt battery
160*12=around 2000 watt
now comes the tricky part ...the panel ....we have got 2000 watt ...that needed to be collected ....hopefully in one hour ...but that is impossible because 2000 watt panel will produce large currents that will destroy the battery
many suggest the "GOLDEN RATE " of c/10 where c is battery capacity now we do have 160 amper battery /10 that is 16 amper
so we have to buy that panel that gives 12 volt at 16 amper and we have achieved that "golden rate"
panels that charge 12 volt batteries are not 12 volt panles ...they are 18 volt vmp panels .....vmp is the maximum power voltage ..
so we need 18vmp panel at 16 amper ....despite the fact that 18 panel @16 amper panel is a 290 watt panel ...but because we use a pwm controller in this design
18volt @16 amper is never a 290 ...because pwm controller will only use 13.5 at 16 a and toss the extra voltage
which will "DRAW' only 216 watt out of 290 watt panel ....
even designing this system with mppt is ok .. that will allow us to buy panel that has 18 volt at lower current than 16 ...
the extra lost voltages that pwm tosses mppt convert to current and thus
we wont lose money by buying large panel that we only draw little watt out of it
...sorry for this long prelude but in a nutshell by following "solar bibles" we find our self with a
SOLAR PANEL THAT HAS POWER RATING THAT IS 1/10 OF THE BATTERY WATT
IN our case 2000 watt battery (12 volt *160) and the panel is 290 watt (from which we get only 216 watt due to pwm controller) or 200 watt panel
18 at 11 amper panel if we use mppt ....despite the fact that the mppt will charge battery at 13.5 but turn the lost voltage into current
which will crank up current into 16 amper again
so how some system manage to charge batteries in 4 hours time if we follow the rules we only find our self with panel that 1/10
of battery wattage which will force the harsh fact that our panels will collect our needed power in 10 hours time
very very long and perfectly impractical even in the middle east countries (libyan man here )
thanks every body please share your thought with me
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