Sharing here a Google translation of a tutorial about power
…
Design your system according to your needs.
For this, nothing like a concrete example:
- To calculate your needs in Wh (or kWh) here is the procedure to follow.
Suppose that on average, you use an 11W fan for 5 hours everyday.
Your consumption is therefore: 11W x 5 hr = 55 Wh.
You then calculate in the same way for all your used devices
regularly. Example:
Ventilo = 11W x 5 hr = 55
Laptop PC = 50 W x 3 hr = 150
TV = 80 W x 2 hr = 160
Total Watt hour = 55 + 150 + 160 = 365
Considering 30% loss in a system:
365 x 1.3 = 474.5 Wh that can be rounded up to 475 Wh.
The next thing to do is to choose the components compared
to this consumption.
- The solar panels will have to be selected so that they load the
batteries totally, in a day.
In a “day” of 12 hours, there will be (depending on where you live), that
4 hours of real exposure to the sun (it will be necessary to see in relation to your region).
But let’s take this value which is a value “refuge”
The necessary power (We) that we must have in our example is therefore:
475Wh / 4 = 118.75 W! By taking a margin, we must choose a panel
120 Watt (12V).
N.B: I say 120W 12V panel because we will charge 12V batteries.
In reality (as I say in the videos), the panel will release something
like 17 volts or more …
- It’s time to talk about the battery:
Power = Voltage x Intensity
Watt-hour = Voltage (Volts) x Intensity (Amps) x Time (Hours)
Battery voltage = 12V (we use a 12V system)
Battery capacity = Consumption / Voltage = 475/12 = 39.58 Ah
(Ampere-hour)
But the batteries are not perfect, so we have to consider a loss
15%. The battery must therefore have a capacity of: 39.58 / 0.85 = 46.56 Ah.
NB: It should not be unloaded 100%. For long cycle batteries
for example, a maximum discharge of 60% can be accepted.
Which means that the actual capacity of the battery must be:
46.56 / 0.6 = 77.61 Ah
So in this example you can choose a deep cycle battery
with a capacity greater than 77.61 Ah.
We will opt for a commercial battery at 80Ah.
- To conclude and answer the questions I receive about
homogeneity of the system:
Here we have a homogeneous system because:
We have a daily conso of 475Wh, so we take:
- 1 120W panel,
- 1st battery 80Ah,
- and a corresponding charge controller (120W (panel) / 12V = 10A).
Take a 13 A or 15 A charge controller (to be comfortable).
Here! It’s simple and fun to do.
We have a homogeneous system: no component is overused or underused.