If you live in example south spain where its alot of sun the most of the time... Just curious, if somebody have the time and want to explain for a rookie
Okay off the gird ie using batteries for the dark cost a ton more.
Grid tied can save a lot of money if the place you are in allows metered swapping.
my big array does 1 megawatt a day
we burn 110kwatts an hour or 2.64 megawatts so 2.64-1 = 1.64 megawatts out of our pockets.
but if your array did same 1 megawatt during sunlight
and you burn 40kwatts an hour for all 24 hours the grid banks the 1 megawatt for night time.
so 40 x 24 = 960 kwatts. so 1000-960 means you are owed 40kwatts of power for that day.
but you need a place that does fair net meter.
Some places would not net meter the 1 megawatt you generate. so 45 x 7 = 315 kwatts is all they would give you. even though you created 1000 kwatts or 1 megawatt.
Now with batteries it means you need 960 x 2 = 1920 kwatts charged into the batteries since you can only run down a battery about 50%.
Now a small system scales different but if you do on grid and do net meter your savings are more than 35% over no meter power grid. You save about 50% over batteries.