i'm going to talk about how to truly
properly size your solar system
how much power batteries can really
store and the way of solar system really
works because it's pretty amazing how
many people that have solar systems
don't truly understand how much power
they have
and it's important to know because if
you end up with a situation where your
modules break your solar panels aren't functioning
for a period of time or you have a series of cloudy days
it's good to understand exactly how many
kilowatt hours you can actually pull out
your battery safely
so how many days and how you can ration your power
and also that really helps you
sighs your system properly without with
what appliances you're using so I'm
going to start by explaining how the
batteries are set up that first one to
say the caps are off the batteries right
now because I'm equalizing explain that
in another video but hydrogen gas is
escaping right now and you don't want
these caps on while that's happening
so right here I have eight Deka LT16 batteries
now these are 350 amp hours batteries
i'm going to explain as part of what I
can explain today what that means but
before I do that
these are set up in two strings parallel
together so we have four batteries
a group of four batteries that are in
series which means that they're wired
from the positive to the negative
positive to the negative positive
to the negative and then positive to the
positive and negative to the negative
over to the next string when you wire
for batteries in series
every time you do that the amperage
stays the same but the volts double
so each of these batteries is 6 volts so
when I put 4 in series i end up with
essentially one bigger 24 volt battery
the amps are still the same though
so what i have here are two 24 volt
batteries and then they're parallel together
negative 2 negative and positive to
positive and when you parallel
two batteries together you double the
amprage so I have
sized my battery system to make this 24
volts with double the amperage
of a single battery
so each of these
batteries is 350 amp hours
ok so first i want to clarify that when
your solar panels on the roof
the electricity that they generate you're not
using that electricity directly
you're never using that electricity
directly any time you pull power from
solar system you're always pulling from
the batteries
the solar panels send electricity to the
charge controller and the charge
controller reads what the voltage of the
battery system is and maybe even
a couple other metrics and it determines
how it should charge these batteries
so if you're using power during the day the pleading power from these batteries when
the sun's out that electricity from the
panels is actually directed into
the batteries to charge them but it's not
actually but the the power that you're
using your pulling power from the
batteries and the solar modules
through the charge controller are
charging the batteries back up
that's the best way to look at this so
that being said you only have as much
power to use as what's stored in the
batteries
now i have four 225 watt modules and at best they can produce about 200 watts each
when the Sun is very much perpendicular
to the panels and it's the strongest
it's going to be in the sky so that
makes eight hundred watts but 800 watts
isn't the amount of power have available
i have far more than that
800 watts is just the maximum potential
of electricity that the charge
controller can send to charge these
batteries
now the way you figure out how much
actual electricity you have to use is
through the amp hours of these batteries
so let's assume that these batteries
have a 100% charge their 350 amp
hours each
so let's go back and to reference how
these batteries are set up
there's four batteries in series two
pairs of that and when you do that
you're doubling the volts but the amp
stay the same so this
each of these strings each of these
strings of batteries are actually still
350 amp hours each
because the amps don't change when you
put them in series I'm doubling the volts
every time to reach that 24 volts
from the individual 6-volt batteries
so we have 350 amp hours here and 350 amp hours here now they're parallel together
and when you parallel you're doubling
the amps
so what you end up with going to the to
the solar system to the inverter and
to your dc breaker boxes we have 700 amp hours
of 24 volts of 24 volt dc power
available to us at a 100% charge
now let's talk about what that means
Ohm's law says that wats equals volts
times amps so if we have 24 volts and
we have seven hundred amp hours
this is going to if we multiply those
together we're going to get watt hours
so if i take 24 and multiply that by
seven hundred i get sixteen thousand
eight hundred watt hours
now you're more probably everyone is
more familiar with what a kilowatt-hour
actually is a kilowatt-hour is when you
use a thousand watts for one hour
kilowatt is a thousand watts
so I have sixteen thousand eight hundred
watt hours
so what I actually have here if i divide
16,800 by a thousand is 16.8 kilowatt hours
there you go everyone's use the scene
kilowatt-hour usage on their electricity
bill now most people are also saying
right now
well I use far more than that in my home
well in your home you're paying to heat
and cool your house with electricity
also your appliances are geared towards
a higher consumption home but in worship
16.8 kilowatt-hours goes a really really
long way
so that's a very important piece of
information here how many kilowatt hours
your batteries have when they're
fully charged so i have almost 17
kilowatt hours in these batteries
now I never really want to go on a
normal day below seventy percent
usage so in an average day I got 16.8
multiply that by thirty percent
I never really want to use more than
five kilowatt hours of power out of
these batteries a day because when you
keep them at seventy percent full at the
end of the day and they sit like that
overnight
you're going to experience a
really long lifetime with these
batteries but if you start pushing it
every day to 50 and 40 and 30 and 20
percent down
you actually start using 10 12 13 14
kilowatt hours on this system you're
going to damage the batteries and you're
not gonna live a long life
these batteries should live back in 8 to
even 10 years if cared for properly but
you might reduce you might have that if
you take your battery's down to the sub
fifty percent level daily if you need to
use more than five kilowatt hours on it
system like this per day
you should really expand your system so
five kilowatt hours
there's a reason why thirty percent of
these batteries is five kilowatt hours
that's because the system is sized
proportioned in such a way that
5 kilowatt hours is actually the average
of what my solar panels on the roof
will produce in one normal day
so let's talk about how many hours of
sun i have,  i have about four hours
maybe even five hours of the day
where the Sun is at its peak and I'm
really producing a significant amount of power anywhere
between 500 and 800 watts at my 800 watt potential for my solar panels
so if we do the math here
i'll say an average of 750 sorry i'll
say an average of 650 watts on producing
for five hours and out of every day
that's the bulk of what I'm producing
everything going to take 650 watts and
i multiply that by five hours i get
3 250 watt hours which is 3.25
kilowatt hours per day of that five hour
period but it's also producing power
throughout the other hours of the day
just not quite as much
so basically
in an average day in the house
my four 225 watt rated panels will
produce approximately five kilowatt
hours
so if i use five kilowatt hours in a day
get down to thirty percent the next day
my modules will fully charge
what will make up for that usage but I'm
sizing my house
not at five kilowatt hours I'm sizing my
appliances to use more like 3.5 kilowatt
hours per day
that's my fridge and any any AC devices
i have that's my lights
that is my washing machine every my
computer things like that so I am sizing
everything to use three point five
kilowatt hours per day
that is only that's somewhere around
twenty percent of my batteries can hold
and that ensures that the next day I
will more than top out these batteries i
will fully charged them and they will
get into a flow state which means it's
just a trickle charge and that's really
where you want to be so if some days
i use more than 3.5 kilowatt hours i use
more like five even six or seven or even
ten some days
that's mine but on average damn using
three point five kilowatt hours and
that's what I want to come and try to
stay around
