The first step in building a solar power system is to determine the size of the solar power system. We will help you answer questions such as:
– How big should the PV solar capacity be?
– What size of solar panels should you buy?
– How big should the inverter/battery be?
If you do not dimension the solar system correctly, it can cause you not to install the right type of solar system.
Components of a PV solar system
To size a PV solar system, we need to understand the different components of a PV solar system.
The different components of a PV solar system are:
– PV solar module
– Solar inverters
– Charge controller
– Batteries
PV solar modules (solar modules)
Solar panels contain solar cells that convert the incident sunlight into direct current (DC). To achieve the desired voltage and current, group the modules into a larger row (PV array). Connect the PV modules solar panel (Learn how to connect series vs parallel here) to generate the desired voltage or current.
Solar Charge Controller
It controls the output voltage and current from the solar panels to the battery. It helps to prevent overcharging and discharging of the current.
Solar inverters
Solar inverters convert the direct current output of the solar modules into usable alternating current (AC).
Batteries
They store the energy generated by the solar modules in the form of direct current (DC).
Load
These are the devices that use the electricity generated by the PV system or electricity from the grid.
Energy efficiency
Before you do the solar design, you should consider how you can make the system more efficient. Increase efficiency by implementing energy efficiency measures. This reduces the solar power output of the PV system. Some of the measures to increase the efficiency of the system are: use efficient equipment and, where possible, use natural resources such as sunlight, wind, etc. This reduces dependence on fossil fuels. It also reduces energy costs. At this point, it’s important to check your power consumption and reduce your power needs as much as possible. This is true for any system, but is especially important for home and smelter systems, as the cost savings can be substantial. First, identify the large and/or variable consumers (such as water pumps, outdoor lighting, electric stoves, AC refrigerators, washing machines, etc.) and try to turn them off or consider alternatives such as propane or DC models. The initial cost of DC devices is usually higher than that of AC devices, but you avoid energy losses when converting DC to AC, and usually DC devices are more efficient and last longer. Replace light bulbs with fluorescent bulbs wherever possible. Fluorescent lamps offer the same illuminance with lower wattage. If you can’t do without a large consumer, you should only use it during the main hours of sunshine or only in the summer.
Design of PV solar systems
How big is the roof area, façade or the outdoor area?
Most houses have roofs on which solar panels can be attached. However, if your roof has windows, dormers, chimneys, or a vertical vent, it could reduce the space for a solar system.
Load-bearing capacity of the roof
Make sure your roof can support the weight of the chosen system. The weight of a single module varies from brand to brand, but the standard 60-cell solar panels used in most home and smaller systems weigh about 18 kg-20 kg. Most homes have roofs that can easily support this weight. An installer will determine this as part of their initial inspection and check whether work is needed to reinforce the roof.
Components
The components provide the connections and standard safety features required for each electrical system. These include: generator junction boxes, properly sized cables, fuses, switches, circuit breakers and meters.
Solar module load
Determine the average power consumption requirement. Then calculate the total wattage hours per day. For this purpose, the average watt hours consumed by the various devices per day are measured. Then calculate the total wattage hours per day to be delivered by the solar modules. Multiply the total wattage hours per day by 1.3 (the energy lost in the system). In addition, there is a solar calculator that can help you estimate how many portable solar panels for home you need based on the power and duration of each electrical appliance. This results in the total power that must be supplied by the solar panels. Depending on the size of the PV modules, a different amount of energy is generated. Therefore, create a list of the devices and/or consumers that you want to operate with your PV system. Determine how much power each device consumes during operation. Most devices have a label on the back that indicates the wattage. Other sources of information are technical data sheets, local equipment dealers and the product manufacturers or information from the Internet about the devices.
AC and DC loads
These are the devices (such as lamps or radios) and the components (such as water pumps and microwave amplifiers) that consume the electricity generated by your PV system.
PV solar module
In the previous step, we calculated the total wattage hours that the solar modules have to deliver per day. Now calculate the average daily maximum hours of the sun at your location. Divide the total power to be delivered by the PV system by the peak hours of the day. This gives the approximate size of the system in KWh. Divide this value by the efficiency of the solar modules to obtain the power output of the solar modules. To calculate the number of modules required: Divide the total watt-hours to be produced by the rated power of the PV modules. This results in the number of PV modules required.
Installation of solar modules
The modules are connected in series and/or in parallel to generate the voltage and current values required for your needs. The system is usually mounted on a metal structure and oriented towards the sun. There are many brands of solar panels, and each brand is slightly different in size. Some brands of solar panels have a larger capacity and therefore require a smaller roof area. A solar panel consists of a series of small photovoltaic (PV) cells that are wired together. Most systems use solar panels that contain 60 of these cells. A complete system (also called an array) consists of a series of solar panels that are usually placed next to each other.
Solar inverters
The solar inverter converts the DC power of the solar modules or battery into usable AC power. Therefore, the dimensioning of the solar inverter is important so that the conversion takes place correctly. The power of the inverter is given in watts. The wattage of the inverter should be equal to or higher than the wattage of the solar powered generator system. For devices such as motors, the size of the inverter should be at least three times the power of these devices. This is necessary to cope with the surge current when starting this type of devices. In the case of a grid-connected system, the input power should correspond to the power of the PV system to ensure safe and efficient operation.
Solar Charge Controller
Although charge controllers can be purchased with many optional features, their main function is to keep the batteries at the right state of charge and protect them from overcharging. The solar charge controller is designed with ampere and volt capacities. Choose a solar charge controller that matches the voltage of the PV system and batteries. Make sure that the solar charge controller has the capacity to process the electricity supplied by the PV system.
Battery size
With a grid-connected solar system, a battery is not required. It is required in the case of an off-grid solar system or a hybrid solar system (a mixture of off-grid and off-grid solar system). Choose a lifepo4 battery with a capacity at least as large as that of the solar panels. The battery capacity is measured in ampere-hours. Determine the watt hours by multiplying the ampere-hours by the voltage of the battery.
For example, for a 40AH and 10V battery, the watt-hour count is 40(X) x 10(Y) = 400 WH(Z).
This means that the battery should provide 400 watts for 1 hour or 200 watts for 2 hours, i.e. the more energy you take, the faster the battery is discharged. However, you cannot get all the power from the battery. As soon as the voltage drops below the voltage of the device to be supplied, the battery can no longer supply it.
To calculate the battery size, select the multiplier below, which corresponds to the average ambient temperature in winter that your battery bank will be exposed to.
Ambient temperature multiplier:
25ºC 1.00 am
21ºC 1.04
16ºC 1.11
10ºC 1.19
5ºC 1.30 am
-1ºC 1.40
-7ºC 1.59
Overview of various devices and wattages*
Below are the most devices used with an indication of the average wattages:
Coffee pot 200
Coffee machine 800
Toaster 800-1500
Mixer 300
Microwave 600-1500
Hot plate 1200
Washing machine automatic 500
Washing machine manual 300
Vacuum cleaner standing 200-700
Vacuum cleaner Hand 100
Sewing machine 100
Iron 1000
Tumble dryer Electric 400
Tumble dryer gas heated 300-400
Water pump 250-500
Ceiling fan 10-50
Table fan 10-25
Electric duvet 200
Blower dryer 1000
Shaver 15
Computer Laptop 20-50
Computer PC 80-150
Computer Printer 100
Typewriter 80-200
TV 25″ color 150
TV 19″ Color 70
1TV 2″ BLACK AND WHITE 20
VIDEO RECORDER 40
CD Player 35
Stereo system 10-30
Clock Radio 1
Satellite dish 30
CB radio 5
Electric Clock 3
Lighting: 100W Light Bulb 100
Lights: 25W Compact Fluorescent Lamp 28
Lights: 50W DC incandescent lamp 50
Lights: 40W DC Halogen 40
Lights: 20W Compact Fluorescent Lamp 22
Compact fluorescent lamps: 40 watts equivalent 11
Compact fluorescent lamps: 60 watts equivalent 16
Compact fluorescent lamps: 75 watts equivalent 20
Compact fluorescent lamps: 100 watts equivalent 30
1/4″ drill 250
1/2″ Drill 750
1 inch Drill 1000
9″ Disc Grinder 1200
3″ Belt Sander 1000
12″ Chainsaw 1100
14″ Band Saw 1100
7-1/4″ circular saw 900
8-1/4″ circular saw 1400
Fridge/freezer 20cf 1.8Kwh per day (15 hours) 540
Fridge/freezer 16cf 1.6Kwh per day (13 hours) 475
Freezer 14cf (15 hours) 440
Freezer 14cf (14 hours) 350
Freezer 19cf (10 hours) 112
Most devices have a label on the back that indicates the wattage. Other sources of information include local equipment dealers and product manufacturers.
