# Solar Panels & Batteries: Solar Power Components – Part 1

Hi. I'm Amy Beaudet from the altE Store. Thank you for watching our video series. This third video is called Solar Electric
Components , and we're going to break it down into multiple parts to keep it manageable. If you missed our earlier videos, I recommend
you go back and watch the earlier ones in the series to get a good foundation.We re-going
to go over some of main components in a solar electric system; the solar modules, batteries. Keep in mind that technology is moving forward
at an incredible rate, so I'm going to make some generalities that are true today, but
there are likely to be exceptions to most rules discussed.Before we go further, I want
to go over a quick reminder on wiring in series vs parallel. Wiring panels in series, where the negative
of one is wire to the positive of the other, results in the current staying the same, but
the voltage increases. Two panels in parallel, where the two positives
are wired together and the two negatives are wired together, results in the voltage staying
the same and current increasing.

It s important to note that regardless of
the way it is wired, the power, or watts, remains the same. Since watts equals volts x amps, it doesn't
matter if it is series or parallel. Likewise, when batteries are wired in series,
their voltage increases, and when wired in parallel, amp hours are increased. You'll often see multiple rows of panels or
batteries wired in series, each row is a string. You can then wire multiple strings in parallel. This allows you to get both higher voltage
(with series strings) and higher amps or amp hours (with parallel). In this example of 2 parallel rows of 4 batteries
wired in series is called 2 strings of 4. You can see that wiring (4) 12V batteries
in series equals 48V, and wiring those 2 strings in parallel doubles the amp hours to 160ah. The power of this array is 160ah x 48V, which
equals 7680 watt hours.Let's start with the solar panels, or PV Modules.

Solar panels generate DC electricity when
exposed to sunlight via the Photovoltaic Effect, first observed by a French physicist in 1839. A simple explanation is that the photons from
sunlight are absorbed by a semiconductor material, generally silicon. The negatively charged electrons are knocked
loose from their atoms, and flow from the negative side to the positive side to recombine
with available holes there. This creates a direct current flow. This flow of electrons can then be used to
either directly power a DC device, like a pump or a fan, it can be used to charge a
battery bank, or it can be inverted to AC power to use in your home.Each solar cell
generates about 1/2V. That's not much for practical use.

So multiple cells are wired together in series
to create higher voltage, creating a solar module, commonly referred to as a solar panel. A typical 12V solar panel has 36 cells in
series. The larger a solar cell is, the higher the
current. So the cells of a 200W panel are generally
bigger than a 100W panel. Multiple solar modules wired together then
creates a solar array. You can see the difference in the look of
a 12V module compared to a 24V module.

As with anything, there are exceptions. We do have some 12V modules that have 72 cells,
but the cells are wired in 2 parallel strings of 36 in series, creating the 12V.Each module
has a label on the back, stating their specs. Here s an example of a Kyocera 140W 12V module. It lists the rated outputs for the panel,
as well as any certification it has.

The ratings are actual outputs under standard
test conditions, so the numbers you measure in the real world may be slightly different. Let s go over each of the specs for a solar
module.Open Circuit Voltage is the voltage you will measure when nothing but a voltmeter
is connected to the solar panel. This is the highest voltage the module will
output at 77 degrees Fahrenheit with the sunlight intensity at 1000 watts per square meter,
which are just a few of the details of standard test conditions, or STC. The voltage will be higher when it is colder
out, and lower when it is hotter. Short Circuit Current is the amps output with
no load on the panel. It is the highest current possible at STC. There are times when the output could be higher,
for instance when the sun is coming out from behind a cloud, you can see the silver lining
, where the edge of the cloud is magnifying the sunlight, causing the intensity to be
brighter than STC.

This brings us to the two specs which are
when the module is connected to a load, so more real world conditions. But still at the temperature and brightness
listed under STC. Maximum Power Voltage is the actual voltage
the module will output when connected, and Maximum Power Current is the amps output while
under load.PV modules were originally designed to charge battery systems, so it is typical
to see panels listed for what voltage battery bank it is able to charge. Nominal voltage is a shorthand grouping term,
originally based on battery voltages (for example, 12V, 24V, 48V). To charge a 48V battery bank, you simply wire
four 12V modules or 2 24V modules in series to add up to 48V. In general, you can determine what nominal
voltage the module is by the number of cells on the panel.

A 12V nominal panel usually has 36 cells,
and its Open Circuit voltage is about 22 volts, and its Maximum Power voltage is around 17
volts. However, as grid-tied solar systems that don't
use batteries have become more popular, you start to see different size nominal panels
that don t logically line up with battery bank sizes. The most popular size modules used in grid-tied
systems today are 60 cell, 20V modules. The wattage of available panels has been increasing,
and many manufactures are achieving that by increasing the number of cells, increasing
the voltage of the panels.

As you recall, watts equals volts times amps,
so increasing the volts while maintaining the same amps increases the watts. As such, there are 80 cells and higher available
these days.Let s move off PV modules onto batteries. Solar panels have no way to store power, you
use it or lose it. Batteries allow you to store power to use
later, by using the power generated by the module or other power source to charge the
batteries. Batteries used in a solar system MUST be deep
cycle batteries. These are made very differently from car batteries.

A car battery has the internal plates designed
to send a short, high current blast to start the engine. It then gets recharged quickly by the alternator
to send another short blast hours later. A deep cycle battery is designed differently. It is designed to be gradually charged and
discharged over a course of hours. If you try to use a car battery for an off-grid
system, it will work for a short amount of time, but you will very quickly kill the batteries. PV systems can have many batteries, each of
them can weigh 50, 100 pounds, or much more. Additionally, there are losses inherent in
batteries as they convert electrical energy to chemical and back to electrical: 5-15%
of energy lost to storage and extraction. Additionally, you should never use more than
50% of the rated capacity, or you will quickly reduce the battery s ability to hold a charge,
and have to replace the bank.

These losses need to be taken into account
when calculating the size of your battery bank. When selecting a battery for your system, there are 2 primary
types of batteries available, flooded or sealed. A flooded lead acid battery has removable
vents that you must remove to check the specific gravity of the acid and add water on a regular
schedule, usually once a month. Because it is not sealed, it is designed to
output the hydrogen gas that is created during its charging process.

Therefore the battery bank MUST be properly
vented to the outside. If you are looking to have flooded batteries
shipped, be aware that they are considered hazardous material by the Department of Transportation,
so additional precautions and expenses may be required. The advantage of these flooded batteries is
that they are less expensive than a typical sealed battery, and a well maintained flooded
battery will generally last longer than a typical sealed battery. But if you neglect the battery and do not
handle the maintenance, you will quickly have a dead battery bank on you hands. Sealed Lead Acid batteries are most commonly
available as either AGM or Gel. This refers to the form of the electrolyte. An AGM battery has the electrolyte in a spongey
mat, and the gel batteries have a thicker gel that keeps itself distributed within the
battery. There are pros and cons to each of these designs
that we won t get into, but in general , both types of sealed batteries are very similar.

The biggest pro of sealed batteries is that
since they are sealed, they won't spill or outgas. This makes it a safer option than flooded
batteries. They also don t require the monthly maintenance,
just occasionally inspect them to see that they look to be in good shape. Sealed batteries are an excellent choice for
battery backup systems that aren't charged and discharged every day, but require a long
standby period. They also do better in extreme cold. The downside to the sealed batteries is that
they tend to be more expensive than a flooded battery, and have a shorter life than a well
maintained flooded battery. But it you are not able or willing to maintain
a flooded battery, sealed is definitely the way to go.

Just as Watts = Volts x Amps, Watt hours = Volts
x Amp hours. This will come in handy when we size our battery
bank. Many people ask how long they can run things
from a battery. This depends on how deeply you discharge the
battery, known as depth of discharge, and how quickly you are drawing current out of
the battery. If you are drawing 2 amps out of a battery
for 4 hours, this is using 8 amp-hours. As I mentioned before, you don t want to use
more than of the stored power in a battery, so the most power you want to take out of
a 92 amp hour battery is 46ah. So if you are running that same 2 amps for
23 hours, you would have drained the 92 ah battery to 50% depth of discharge.

The amount of power that a battery can store
varies based on a number of variables, including how fast you charge and discharge the battery. In this example, you see that if you charge
and/or discharge the battery over 5 hours and a rate of 49 amps, it can store half the
power than if you did the same over the course of 100 hours at 4.6A. Most batteries are rated
at 20 hours, basically how much power you can use during a day. If you are using power faster or slower than
20 hours, you must adjust the sizing accordingly. The amount of power that a battery can store
varies based on a number of variables, including how fast you charge and discharge the battery. In this example, you see that if you charge
and/or discharge the battery over 5 hours and a rate of 49 amps, it can store half the
power than if you did the same over the course of 100 hours at 4.6A. Most batteries are rated
at 20 hours, basically how much power you can use during a day. If you are using power faster or slower than
20 hours, you must adjust the sizing accordingly.When selecting a battery, you must decide between
flooded or sealed, what voltage battery, and how many amp hours.

You need to keep in mind the size and weight
of the batteries, will they fit in your available space? Also note what terminals they have to connect
the battery cables.Check out our website for a great selection of solar panels and deep
cycle batteries available. Also watch more of our Video Series on our
web site, including part 2 where we cover charge controllers and inverters. We've got a team of highly trained Technical