4w solar power system
How to build a Simple Solar panel System
This is a complete guide to show you how to make a simple yet effective solar
panel system that you can power small mains appliances off of.
All hardware used:
4 watt solar panel (from ebay) £25/$50
7 amp black and decker electric strimmer battery(had it already)
cigarette lighter socket(from extender thingy)
PSi 150 150watt power inverter from B & Q £20/$40
total cost= £50/ $100
A crude
picture of the finished system
The finished system can run small aplliances like laptops.
I run my powerbook 1400 off it and lasts for up to two hours if the 12v battery
is fully charged. You can also run 12v appliances like phone chargers which
plug into the cigarette lighter socket.
The the first part is the solar panel which charges a
12v battery.
The type of solar panel I am using is an amorphous 4
watt solar panel bought off ebay for £24(approximately 50$).I would recommend
a higher rating(i.e 9 watts) and a better type(monocrystalline/polycrystalline)
for faster charging. It has to be 12v.I got the solar panel off ebay, simply
do a search for "solar panel".To connect to the charging port I snipped
off the wire from an old 12v power adaptor(any rating will do) and wired it
into the back of the solar panel(white side positive). Some solar panels have
junction boxes at the back for connecting wires to it and you will have to screw
off the cover. Connect one wire to each terminal. Smaller ones may just have
2 wires sticking out the back, in which case you will have to twist each wire
onto your cables. If you can solder then that would be preferrable. Make sure
the bare copper wires are not touching each other, cover the joins with heat-shrink
tubing or tape.
Normal car batteries are not suitable for systems like
this because they're designed just for starting cars and will get damaged if
fully discharged. I have used a strimmer battery becuase they are designed to
be charged a lot and are quite powerful.My one also has a built-in charging
port. If you are buying your own it should be a deep cycle lead acid battey
and around 10 amps(17 ah from a jumpstart powerpack would work great(get a more
powerful one if you want to run for longer but this means that you should get
a larger solar panel))but I would use an electric strimmer battery(or simalar)
because it is in a case with all the wiring. I simply plug the solar panel into
the charging socket. If you get a battery with no casing, you will have to get
a diode to use with the solar panel if it is not protected already. These are
quite common and can be bought from electronics stores. Place it so that the
side with the thin strip is facing towards the battery on the positive(+ or
red). Connect it to the terminal and connect the solar panel positive to it.
Connect the negatives together(- or black).
The Battery terminals on my battery are 2 thick pin things.
I used small crocodile clips to connect to them and then covered them in insulating
tape. You may have to use a voltmeter to check the polarity.An optional extra
is a switch, connected to one side of the battery and on the other side of the
switch connect to the main cable that the switch had replaced. I got mine from
an old computer power supply but you can get them from lots of things.
Warning: Make sure
that no metal objects or wires cross the batteries terminals. It can spark and
the metal object can get extremely hot and cause a fire.
The cigarette lighter socket was from an extender/angle
thingy that I took apart and wired the top part into the cable. The middle part
is positive, the outside part is negative. Cigarette lighter sockets from car
stores would work equally as well.
To find out how long it will take to charge the battery
you need to find out the power(in amps) and the capacity of the battery. For
example, if the battery is completely empty then my solar panel which is around
300 ma(sometimes more)(12v/4W) in sun. This would mean that around 1 amp would
be put into the battery after three hours of charging(300ma=0.3A so 1/3.3 is
3). To fully charge the battery from absolute empty it would take 24 hours of
sunlight.
The inverter plugs into the socket and converts the 12v
electricity into 240v which can be used for everyday appliances up to its rating(mine
was 120 watts).
You charge the battery, plug the inverter into the socket,
switch it on and off you go!
To make it look better I've mounted it inside a case
from an old sony tape deck unit that I stripped the electronics out of.
Here are some pictures of the finished thing monted in
the case.
Front of the case(cooling fins were supposed to have
a fan in front of it but there wasn't enough power).
System with case taken off.
Charging port.
Solar panel out on roof.
Note:I would not recommend this system any longer as there is
better designs on my site.