How Do I Design A Solar Power System?
How do I design a solar power system?
How do I design a solar power system?
Well, you start at the beginning. Actually thats not strictly true, really you start at the
end, by optimising your loads. Then you size the battery and solar array, then the
controller and inverter. Finally you decide where all the things are going and size the
cable.
The following process will give you an approximation for the United Kingdom, and
other countries with a similar climate. For detailed worldwide design calculations see
the Solar Power Design Manual.
Optimise my loads?
Yes; before you start designing you need to know that youre designing the right
thing. Thats what optimising your loads is all about.
So I should start weighing things?
No, not those sort of loads. The load on the system is the amount of power it will have to supply, averaged over time. So optimising your loads is about reducing the number of appliances you have, reducing the time you use them for and picking the appliances with the lowest power consumption.
Why would I want less appliances?
Its like this; every extra Watt of electricity or every extra hour that somethings on
for is an extra bit of solar panel, an extra bit of battery, an extra bit of controller and
maybe an extra bit of inverter. These things arent cheap; the way to make an
affordable solar power system is to do a good job of optimising your loads.
Ok, how do I do it then?
Ive done it for you, sort of. For a rough idea, try the pop-up calculator on my design
page. Keep trying until you get the smallest possible answer.
Done that, what next?
You need to size the array.
Size the array? Whats that?
The array. Thats the term used for a number of solar panels connected
together. There is a maximum practical size for a solar panel so its normal to connect more than one together for big systems.
Is there another calculator?
Yup, on the same page. Beware though, its an approximation for the
UK only. If I could predict the weather like that Id be a millionaire.
I need an array the size of Birmingham. What did I do wrong?
Thats what I mean about optimising your loads. Reduce your expectations and do it
again. Keep doing this until either you realise you cant solar power a blast furnace or
you get a sensible answer.
Now then, what size does the battery need to be?
Well that all depends on how many days holdover you want.
Speak English man. Whats holdover?
Simple, its the amount of time that a fully charged battery would be able to power
the system without the solar panels. Thats your decision.
Great. How do I decide?
Its 3. Well, not necessarily; for critical medical applications its at least 7, but for you
3 will do. Dont ask why.
And theres a calculator?
Just like before, at Solar power answers theres a battery sizing calculator.
It says I need 200 Amp hours of battery, so my 500 Amp car battery will do
wont it?
A common mistake that, mostly made by the sellers of car batteries. The output of the
calculator is in Amp hours. A 200 Amp hour battery can provide 200 Amps for 1
hour, 1 Amp for 200 Hours or anything that adds up to the same. The number on a car
battery is cold-cranking amps. A 500 Amp battery can provide 500 Amps for 30
seconds on a cold day. Different altogether. Anyway, what you need is a deep-cycle
battery or at the least a leisure battery.
Not a car battery? Theyre cheap you know.
I didnt believe this myself so I tried it. Take it from me, youll be lucky if a car
battery lasts a month. In a car its always on charge so it will last for years. In a solar
power system it gets discharged daily and will break. Nope, a deep-cycle batterys
what you want.
Im getting the hang of this, can I do the controller and inverter?
Thats the next thing. Lucky its easy, because theres no calculators.
No calculators?
No, sorry, but Im sure youll manage. Lets do the controller first.
Do I really need one?
Yes. Well, almost certainly. The only time you dont need one is if youve got a really
big battery relative to the size of the solar panel or array.
How do I work it out?
On the back of the panels there is a rating for the short circuit current. Multiply this
by the number of panels in parallel and thats the rating of your controller in Amps.
I havent got the panels yet have I?
Oh no so you havent. Youll have to approximate then. Divide the rated output (in
Watts) by 16. That will give you about the right answer. If the total is less than 10%
of the battery capacity you may be alright without a controller if its not going to be
left unattended for long periods and youre not using sealed batteries. I wouldnt
recommend it though.
What about the inverter?
Even easier. Add up the Wattage of all the mains appliances that will be on at once.
Thats your answer.
How do I attach it all together?
Get an electrician. Seriously, you need to have a certain amount of electrical
knowledge before you start. If you have, then read the instructions before you start
and Ill take no responsibility if you set your house on fire. First you have to decide
where to put things.
What goes where?
The solar panels need to face the south, or the north if youre south of the equator.
Can I mount them flat?
No, because youll have to keep cleaning them. Tilt them at about your angle of
latitude, or at least 10 degrees.
And the batteries?
Protected from the elements, but well ventilated. They produce hydrogen gas when
charging and its highly flammable.
And the electronics?
Nice and close, preferably indoors. You need to keep the cables as short as possible.
Why do the cables need to be short?
Because theyre low voltage cables remember. If you half the voltage then you
double the current, so our current is about 20 times what it would be if it was mains.
Why do I care about the current?
Because it determines the thickness of the cables and that determines the cost. Once
again theres a calculator which will help.
How is it wired up?
Pretty much the same as the mains really. The 12 Volt stuff will need thicker cable
than you would imagine; use the calculator to get an idea. Earth the battery negative
and make sure that the 12 Volt and 230 Volt wiring is kept completely separate.
Why is that so important?
To make sure that you can never have 230 Volts on the 12 Volt circuit, thats why.
You could get a nasty shock.
What fittings do I use?
Some mains fittings, some special ones. Look at the wiring page for more
information.
Can you give me an idea?
Of course, look at the sample wiring diagrams on the next page.
by: Yoni Levy
The Search For New Document Collaboration Software The New Neck Travel Pillow Giving Style, Practicality And Design A New Name: Travel Wheelchairs Five Must See Places Of Natural Beauty In New Zealand Experience The New Zealand Buy A New Cell Phone Battery Is A Lithium-ion, Then 3 To 5 Times ENGLISH BULLDOG PUPPIES SEEKING NEW HOME FOR ADOPTION ONLY TO CARING HOMES Obama Met With New Orleans Saints And Said The Nfl Jerseys Super Bowl Champion Significant Home Cleaning Advice For New Parents The Benefits Of The New Training Legitimate Debt Relief - How New Laws Are Great News For Consumers Deep in Debt 4 Simple Energy Savings Tips Anyone Can Do There's A New Sheriff In Town - Mineral Makeup