# Things you have to do  before you  Buy a Solar Panel

1: Look at the cells and making sure there are no fractures in the ends of the cell
2: look at the conductive lines (PASPAR) and confirm
3: Maintaining cell color homogeneity, such as being a dark, dark, light-colored cell, etc.
4: Look at the Junction Box and making sure there are 6, 9 or 3 diodes in the form of a Mosfet. Sometimes they are adulterated into diode-shaped plastic parts
5: Maintain all data on the label

#### Steps to design a solar system (off-grid)

• calculate the loads and here we divide them to AC and DC Then we combine these loads.
• The sum of the two resulting lambs is multiplied by 1.2 in order to overcome the resulting losses
•  We determine the battery system we will use, depending on the nature of the site to be fed(12 V, 24V, and 48V).
• We determine the number of days of storage for batteries, these are not subject to our desire, but to the nature of the area and use.
• If we are in a region where the sun is rarely absent during the day, we choose one day, but if we are in northern Europe, for example, the sun can be absent in the winter for two consecutive weeks and this means that we will choose 14 days to ensure batteries are charged during a The absence of the sun and so on.
• Choosing the percentage of discharging the batteries; It is known that the repetitive discharge of batteries decreases their life and this invites us to choose a small percentage, but this matter is not economical as it means that we will use a larger number of batteries. The type of batteries used has a role in determining the value and the following table highlights the subject:

Maximum Depth of Discharge

Battery Type Default Value

Fortunately, solar batteries have large cycles as modern technology has created solar batteries that have more than 1,000 discharge cycles (overpriced)

Note: When you choose  batteries it is advisable to see the technical catalogs of solar batteries available on the market

Local, there are many websites for battery manufacturers on the internet
• Peak The Amper Hour  (rating for the chosen battery )

• Peak The (Battery Nominal voltage )Volts.
• Peak sunshine hours(PSH) for worst month radiation (Hours/day)
• Peak amperage of the selected module from the Datasheet
• The nominal power rating of the selected module

#### Dimentionment

Calculations can be done in 5 steps:
Step 1: Determine your energy needs
Since you know the devices that you want to power with electricity, you can make two tables, one of which is for the devices that run on DC and table for devices running on alternating current AC.
The schedule can be as follows: