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1. Factors to be considered in the design of a home solar power generation system
1-1. Where is home solar power used? How is the solar radiation in the area?
1-2. What is the load power of the system?
1-3. What is the output voltage of the system, DC or AC?
1-4. How many hours does the system need to work per day?
1-5. In case of rainy weather without sunlight, how many days does the system need to supply power continuously?
1-6. In the case of load, pure resistive, capacitive or inductive, what is the starting current?
2. To build a personal photovoltaic solar power generation system for ordinary families, seven things are mainly needed
2-1. Solar panels
2-2. Solar bracket (mountingsystem)
2-3. Cables
2-4. Solar inverter
2-5. Solar Controller
2-6. Composition of battery (group)
2-7. Meters installed by the grid company
Solar panels: The solar panels are the core part of the solar power supply system and the most valuable part of the solar power supply system. Its function is to convert the radiant energy of the sun into electrical energy, or send it to the battery for storage, or to push the load to work. The quality and cost of solar cell components will directly determine the quality and cost of the entire system.
Selection of solar cell modules - the specific load, quantity， and power of the system, and the time each type of load needs to work every day. (this is the most critical question)
Types and characteristics of solar cells：
Types | Mono-crystalline solar cell | Poly-crystalline solar cell | Amorphous silicon solar cell |
| Conversion efficiency | 12%-18% | 10%-16% | 6%-8% |
| Service life(year) | 15-20 | 15-20 | 5-10 |
| average price | expensive | normal | Cheap |
| stability | good | good | poor stability(decay) |
| color | black/dark blue | dark blue crystal | brown |
| advantages | High conversion efficiency, stable operation, and small size | Stable work and low cost. Widely used. | Low price, good low light performance, mostly used in calculators, electronic watches, etc. |
| shortcoming | high cost | low conversion efficiency | The conversion efficiency is the lowest and will decay. The area of the same power is more than double that of crystalline silicon. |
Solar controller: The function of the solar controller is to control the working state of the entire system, and to protect the battery from overcharge and over-discharge. In places with large temperature differences, a qualified controller should also have the function of temperature compensation. Other additional functions such as light-controlled switches and time-controlled switches should be optional on the controller.
Battery: generally lead-acid battery, in small and microsystems, nickel-hydrogen battery, nickel-cadmium battery, or lithium battery can also be used. Its function is to store the electrical energy supplied by the solar cell module when there is light and release it when needed.
Types and characteristics of batteries：
| Type | lithium battery | Nickel-cadmium batteries | NiMH batteries | Maintenance-free lead-acid battery | |
| colloid | common acid | ||||
| Charge and discharge characteristics | No memory effect, long use time, repeated charging can reach more than 1200 times. 2 hours of fast charging. | The charging and discharging can be repeated more than 500 times, but the memory effect is obvious. | There is no obvious memory effect, and it can be used at any time and can be repeated more than 500 times. 1.2 hours of fast charging. | Resistant to deep discharge, the recovery performance is excellent in the state of power loss, and will not lose capacity due to several power losses. Long life, up to 10 years. | Loss of capacity due to loss of electricity several times will easily make the battery scrapped. The service life is generally 2-3 years. |
| capacity | Lithium batteries of the same capacity are 50% lighter than nickel batteries, and the single-cell voltage is 3.6V | The monomer voltage is 1.2V. The capacity is 200mAh-14000mAh | The cell voltage is 1.2V, and the capacity is 1.5-2 times that of the same volume of nickel-cadmium batteries | The single voltage is 2V, 6V, 12V, the capacity is 5.5Ah-180Ah, 2V can reach 3000AH | Single unit voltage is 2V, 6V, 12V, capacity 5AH-200Ah, 2V can reach 3000Ah |
| Scope of application | Mobile communications, alarm systems, instrumentation, daily necessities, etc. | Solar system, UPS, communication equipment (2V) electric vehicle, power generation, data engineering, etc. | |||
Inverter: An inverter is a device that converts direct current (DC) into alternating current (AC). It consists of an inverter bridge, control logic, and filter circuit. The electricity generated by solar panels is a direct current, and household appliances cannot be used directly. The inverter also has an automatic voltage regulation function, which can improve the power supply quality of the photovoltaic power generation system.
3. Design of Solar Power Supply System
The power of the household solar power supply system needs to be determined according to the power required by the household appliances. It can be estimated from the type of household appliances, power size, quantity, and usage time.
2400W Home / Office Solar Power System
| Design load electrical equipment name | Specifications | Power consumption | Number | daily working hours | Daily power consumption |
| Illumination | energy saving lamps | 11W | 8 | 6 | 528Wh |
| Computer | LCD | 100W | 2 | 5 | 1000Wh |
| Printer | laser | 250W | 1 | 1 | 250Wh |
Fax machine | inkjet | 150W | 1 | 2 | 300Wh |
| Refrigerator | 150L | 100W | 1 | 24 | 2400Wh |
| Washing machine | 300W | 1 | 0.5 | 150W | |
| Microwave oven | 1000W | 1 | 1 | 1000Wh | |
| Air conditioner | 1.5 HP | 1200W | 1 | 5 | 6000Wh |
Satellite TV receiver/VCD | 25W | 1 | 6 | 150Wh | |
| Colour television | 21inch | 95W | 1 | 6 | 570Wh |
| Water pump | 400W | 1 | 1 | 400Wh | |
| Total | 3631W | 12748Wh |
Design for less use of electrical appliances
800W Home / Office Solar Power System
| Design load electrical equipment name | Specifications | Power consumption | Number | daily working hours | Daily power consumption |
| Illumination | energy saving lamps | 11W | 6 | 4 | 264Wh |
| Computer | LCD | 100W | 1 | 5 | 500Wh |
| Printer | inkjet | 30W | 1 | 1 | 30Wh |
Fax machine150 | inkjet | 150W | 1 | 1 | 150Wh |
| Refrigerator | 150L | 100W | 1 | 24 | 2400Wh |
| Washing machine | 300W | 1 | 0.5 | 150Wh | |
| Microwave oven | 1000W | 1 | 0.5 | 500Wh | |
Satellite TV receiver/VCD | 25W | 1 | 6 | 150Wh | |
| Colour television | 21inch | 70W | 1 | 6 | 420Wh |
| Water pump | 200W | 1 | 0.5 | 100Wh | |
| Total | 1986W | 4664W |
4. Recommendation
The solar cell module is the core of the system and the most expensive part. Customers must provide the name, quantity, power, and daily use time of household appliances. Without these data, manufacturers cannot make product plans or make quotations. According to the data in the "Off-Grid Power Generation System Questionnaire" provided by customers in different countries, the manufacturer cannot make a plan at all. At least the name, quantity, and use time of the electrical appliance are required, and the approximate power can be estimated in China. If you need a detailed product plan, you must have detailed survey data.
