Solar on your boat. How to fit solar power to your boat. What you need to know. BEME part 9 In this video we explain the science behind solar and look at wha...

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welcome to boat let's call made easy

part 9 this is solar on your boat it's

gonna be a bit of science in the

beginning of this video it's quite

important that you understand how panels

actually work and then you won't be able

to make an informed decision when you

buy your own panels and start fitting

them to your boat so let's dive straight

in and get to the basics

the Sun is the star at the center of our

solar system it is an any perfect sphere

of hot plasma with an internal

conductive motion that generates a

magnetic field it is by far the most

important source of energy for life on

Earth

his diameter is about 1.3 9 million

kilometers that's about a hundred and

nine times that of the earth and its

mass is about three hundred and thirty

thousand times that of the earth it

accounts for about ninety-nine point

eight six percent of the total mass of

our solar system roughly three-quarters

of the sun's mass consists of hydrogen

around 73 percent the rest is mostly

helium with much smaller quantities of

heavier elements including oxygen carbon

neon and iron at any moment in time the

Sun puts about two hundred and seventeen

point five watts per square meter across

the entire Earth's surface when it's

facing the Sun

light is what is called an

electromagnetic wave just like radio

waves microwaves x-ray waves

electromagnetic waves typically start

with an electromagnetic charge that

jiggles back and forth depending on the

frequency of the electromagnetic wave or

how scrunched together the peaks and

troughs are you get different kinds of

ways for example radio waves they have a

pretty low frequency next comes

microwaves then infrared light the next

is the visible spectrum either different

colors that people can see followed by

ultraviolet light then the waves of

higher frequency called x-rays and still

higher gamma rays Peaks in these the

closest together you'll sometimes hear

that light is made of photons what that

means is that when the light is absorbed

or emitted that energy in the wave comes

in lumps the size of those lumps or

quanta of energy depends on the

frequency the higher the frequency the

more energy in the photons so it's

important to remember that only about

40% of this energy is actually visible

okay you're asking so how does solar

panels actually work well when the

photon hits our solar cell they knock

electrons loose from their atoms if the

conductors are attached to the positive

and negative sides of a cell it forms an

electrical circuit not the ones we've

talked about before when electrons flow

through such a circuit they generate

electricity multiple cells make up solar

panels and multiple panels modules can

be wired together to form a solar array

the more pounds you can deploy the more

energy you can expect to generate so put

simply a solar panel works by allowing

of photons or particles of light to

knock electrons from the atoms

generating a flow of electricity solar

panels actually comprise of many small

units called photovoltaic Souls now

photovoltaic cells simply means they

convert sunlight to electricity so to

work photovoltaic cells who need to

establish an electric field much like a

magnetic field which occurs due to

opposite poles an electric field occurs

when opposite charges are separated to

get this film manufacturers doped

silicon with other materials giving each

slice of the sandwich positive or

negative charge specifically they seed

phosphorus into the top layer of the

silicon which adds extra electrons with

a negative charge to that layer

meanwhile the bottom layer gets at both

of boron which results in fewer

electrons or a positive charge this all

adds up to an electronic field at the

junction between the silicon layers when

a photon of sunlight noxee electron free

the electric field will push the

electron out of the silicon Junction

so here's a summary number one you need

light to strike the cell to release the

electrons number two

the cell has positive and negatively

enhanced layers number three the cells

need to be connected in a circuit number

four cells are arranged in groups to

form panels five panels are arranged in

groups to form an array number six the

bigger the array the more energy you can

generate different parts of the earth

receive different amounts of solar

radiation this is because the sun's rays

strike the Earth's surface most directly

at the equator as you move away from the

equator you will notice that different

areas also receive differents amounts of

Sun lights in different seasons for

example

your geographic location on the planet

and the season will determine how much

energy at peak you can absorb or use

from the Sun the amount of energy you

can get to your cells will also depend

on local factors mountain ranges or even

weather conditions

so let's look at the two types of panel

the types that you're likely to be using

they are monocrystalline and

polycrystalline solar panels both these

types of panel have cells made of

silicon wafers to build up a mono

crystalline or polycrystalline panel

wafers are assembled in rows and columns

to form a rectangle cover with glass or

plastic sheet and laminated together so

while these both made from silicon the

panels actually vary in their

composition mono crystalline cells and

cut from a single pure crystal of

silicon and polycrystalline cells are

composed of fragments of silicon

crystals that are melted together in a

mold before being cut into wafers

because of this their efficiency differs

let's talk about efficiency solar panel

efficiency is another factor that

affects how much energy a particular

panel will produce the efficiency of a

panel refers to the ability of the panel

to convert sunlight into usable energy

here's an example in a panel with 20%

efficiency for instance 20% of all the

light that hits it will be translated

into energy

a panel with a higher efficiency rating

will convert more sunlight into energy

most solar panels have an efficiency

rating of around 15 to 18 percent or the

ones we're going to be using on a boat

anyway so how do we work out what the

efficiency is well there's an

international standard for it but I'll

explain for instance if a thousand watts

per square meter of sunlight hits your

boat panels the amount of sunlight

assumed during an STC testing and your

panel is two square meters you'll end up

with 2,000 watts if your panel is

advertised at producing 400 watts you'll

end up with an efficiency rating of 20%

here's the maths so one of the things

which is most important for you to look

for is the efficiency rating of your

panels so you get the most bang for your

buck as it were

now this table shows the top 10 most

efficient solar panels that you can buy

on the market in 2020 there's a big

difference

twenty two point six down to nineteen

point four and these are all glass

domestic panels okay let's have a

summary we've looked at two types of

make up of solar panels on a crystalline

poly crystalline mono crystalline are

more efficient mono crystalline are also

darker and made from pure silicon

crystals efficiency is important there

is a standard way to calculate

efficiency so you can calculate it or

you can read the panel sticker or check

the specs for the panel

so what else affects the panel's

performance or what you can get from it

well does a few things there's the angle

of the Sun as it's hitting the panel

what time of day it is how hot the panel

gets how clean the panel is and of

course shadow some rigging or a wind

generator the age of the panel if

they're not know how well the panels

made fabricated or constructed surface

scratches and damage the operating

voltage of the panel and also the solar

controller that you're going to be using

all of these have important let's cover

a few of those now in an ideal situation

your panel would be perpendicular or at

90 degrees to the angle of the Sun it's

not always possible on a boat so midday

on the equator when the Sun is directly

overhead that's when you'd get the best

performance from your panel again not

always possible

the standard test for solar panels is

conducted at 25 degrees Celsius or 77 F

so if a panel is rated to have a

temperature coefficient of minus 0.5%

per degree Celsius that panels output

will decrease by half of a percent for

every degree the temperature rises over

25 or 77 F that's a lot the cleanliness

of your panel is paramount to its

efficiency and then you need to say

anymore about that

so some time ago we talked about voltage

higher voltage means lower resistance

better power transmission so a higher

voltage panel will actually be more

efficient than a lower voltage panel if

you're using the same controller and the

same size cable and of course there's

two types of controller on the market

MPPT or ppt who has a lot let's stop for

a cup of tea for a minute I

Oh still there okay someone's gonna say

and why did you go through all the

science bit

I'm not iron stein I'm not a rocket

scientist blah blah blah okay let me put

me tea down a minute now the reason that

we do these videos is to educate people

is to try and give them an understanding

of what they're dealing with if you know

the science behind something if you know

how it works you've got a better chance

of making your own decisions when it

comes to you putting your own solar on

your boat if I just said you need these

panels and you need this charger and

just slap them up there well I wouldn't

be a proper video and it's not my style

to give people stuff in that way I like

to explain things how they work and give

you the opportunity to make your own

decisions based on proper science okay

I'll finish meaty and we'll get on okay

this look a few things type of panel

location charge regulator panel voltage

and how many watch you need let's get

started well first you've got a design

your system no hang on a minute

roll it back the first things we need to

know other energy use your battery

capacity and the battery type before you

start deciding what panels you're going

to use so the first thing you need to

know is how much energy you're going to

use in any particular situation day

sailing night sailing day at anchor or

night anchor and you need to know how

many watt hours you're going to use

without adding any power at all from

your engine or from your solar so first

you need to find out how many amps each

item draws and then how many hours that

are actually going to be running for for

example here our fridge and freezers

only run for about 6 out of 12 hours

multiplying the amp hours used by the

voltage will give you what hours and we

always calculate these things in what

hours alternatively if you've got good

quality battery monitor

it will tell you how many watt hours

you've used and in a 12 hour period

knowing what you use will give you an

idea of how much you need to replace

does that make sense okay let's do some

maths let's say we have or will use

fourteen hundred and forty watt hours in

a 12-hour day sale the next thing we

need to determine is have we got the

battery power to provide this done these

calculations before but let's run

through it again and powers times volts

equals watts so a hundred amp hour

battery times twelve volts is 1200 watt

hours if you have for 100m batteries

that's four times 100 times 12 or 4,800

watt hours yes well yes in theory

however all LED acid batteries flooded

syl gel or AGM should never be

discharged below 50% of their capacity

otherwise you risk damaging the battery

now let's do the maths again looking at

a 50% discharge rate

so 100 amp hours times 12 volts times

0.5 or 50% gives us 600 watt hours we've

now exceeded our battery capacity and

with 4 batteries for 100 amp hours while

that's 4 times 100 times 12 times 0.5

which is 2400 watt hours so with 1440

watt hours for a day so that day sir

would have already taken us down to 50%

of our usable energy from our battery

bank now let's look at the same

calculations for a lithium-ion battery

now lithium-ion batteries are slightly

different

you can discharge them down to 20 or

sometimes 10% of their full capacity

makes a hell of a difference to the

maths so same maths 100 amp hours times

12 volts times 0.85 or 85% that gives us

1020 watt hours and if we do it with 4

batteries that gives us 4 thousand 800

watt hours some massive change

there's also another issue around

conventional lead acid batteries they

can only be charged at 10 to 30% of the

capacity that is bulk at 75 or 80%

capacity the charge rate has to drop off

and they go into absorption full charge

may take hours of charging on float even

the best AGM batteries still have their

limitations so you see it's not just

about your solar it's about your

batteries too but lithium batteries need

different controls in their charging

even if you can charge them at far

higher rates they still have limitations

so the video is up to 15 minutes now and

we still haven't looked at type of panel

that's best for you the location where

you're going to put it on your boat

types of charge regulator and controller

panel voltage how many watts circuit

design safeguards fuses cable sizes

location on your boat lots to come all

in our next video we make these videos

for you please like subscribe and share

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comments and questions are alway

welcome sale safe

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