Recently, my article "Step-By-Step Guide to Building a Home Solar Power Station: Saving Electricity is Actually Very Simple" has been well-received by everyone. Many people left comments saying they were interested, and I also received a lot of private messages. Some netizens even wanted to buy a ready-made one. It seems that although our country's power infrastructure is very powerful, many people are still interested in achieving free green electricity at home.
A netizen said: I want to buy a solar panel at home and assemble one to provide free electricity for the air conditioner. How can I do it? Now let's have a detailed discussion about this issue.
Install a solar system at home that can drive the air conditioner to operate.
In fact, it's very simple. Solar power is input, which is then converted into alternating current through an inverter and output to household appliances for use. The input end can be selected from solar power, diesel power generation or the national power grid. The output end can be chosen whether to connect to electrical appliances through a large-capacity battery (enough for 1-3 days of household electricity consumption), or directly connect to electrical appliances.
Generally speaking, when assembling a household solar system, several key issues need to be considered: the power of the air conditioner, the daily usage duration of the air conditioner, the local light conditions, the capacity of battery energy storage, and the power matching of the inverter, etc.
The following is a detailed introductory plan, suitable for home users to build their own systems.
Generally speaking, the approximate power range of an air conditioner is as follows:
It is recommended to first confirm the maximum power of the air conditioner at home. You can refer to the air conditioner's manual or nameplate, and then calculate the daily usage duration of the air conditioner.
Let's take a look at the parameters of this 1.5-horsepower air conditioner below. Its cooling power is 845W and its heating power is 1240W. Then let's calculate the capacity of the solar panels required based on its maximum power of 1240w.
As mentioned above, the electricity produced by photovoltaic panel cells is direct current and cannot be directly used by electrical appliances. It needs to be converted into alternating current by an inverter.
Then how should one choose an inverter? Look at the maximum power of the electrical appliance.
For instance, the electricity produced by our photovoltaic panels only needs to power this air conditioner with a maximum power of 1240w, and there is no need to worry about other household appliances. Theoretically, we can just buy a 1500W inverter.
However, inverters need to withstand the peak power when electrical appliances start up, especially for loads with large starting currents such as refrigerators, air conditioners, and power tools. Choose an inverter that is 30% to 50% larger than the maximum power. The peak power of the inverter should be greater than that of the starting appliance.
For electrical appliances like induction cookers, the power varies greatly, so it's important to pay attention to the maximum power. When multiple electrical appliances are in operation, select the maximum total power that runs simultaneously and choose an inverter that is about 20% larger.
For instance, in a household, there are usually five 20W lights on simultaneously, one air conditioner with a power of 1240W, and one TV with a power of 150W. Theoretically, you only need an inverter with a maximum power of 1490W. In fact, due to the increased starting power, we need to choose an inverter with a larger power. Therefore, the following 3kw inverter has sufficient capacity.
This single-phase inverter, "single-phase" generally means small capacity for household use. You can choose a capacity ranging from 3kw to 6.2kw.
Choose the capacity according to the number of electrical appliances that need to be connected at home. It also has energy storage function and there is no need to purchase additional batteries. This inverter is used off-grid and is not connected to the municipal power supply. The output terminal can be directly connected to household appliances for use.
If you want to connect to the municipal power supply, you must choose an inverter that can operate in parallel to the grid. Grid-connected inverters have both mains power and solar energy connected at the input end and electrical appliances connected at the output end. When connected to the grid for operation, if the weather is good, it can use the green electricity generated by solar panels. If the weather is bad, it can also switch to the municipal power supply at any time.
The electricity generated by solar panels can be used by electrical appliances through inverters, and it can be used immediately after generation, which is very convenient.
But the air conditioner has to work at night as well. Therefore, it is necessary to combine energy storage to store green electricity for use at night. Nowadays, most inverters come with built-in energy storage batteries, which are called energy storage inverters. These inverters can also support the connection of external energy storage batteries.
Take an air conditioner with a maximum power of 1240W as an example. How many solar panels should be equipped? If the air conditioner in your home is on for 8 hours every day, it will consume approximately 10 kilowatt-hours of electricity.
Solar energy can generate electricity for an average of about 4.5 hours a day during the day. Then you need:
10kwh ÷ 4.5 ≈ 2200W solar panel
How to choose? It is recommended to use monocrystalline silicon solar panels, which have high power generation efficiency and take up less space.
For instance, if a solar panel is 450 watts, then you would need about 5 pieces (450W × 5 pieces = 2250W = 2.25kW).
The photovoltaic controller regulates the current and protects the battery. The MPPT has a higher efficiency and is recommended for use. The current capacity of the controller should be greater than the total output current of the solar panel. However, nowadays many inverters come with MPPT. You can pay attention to it when making a purchase.
The balcony, roof or yard should have sufficient sunlight and face south as much as possible (in the Northern Hemisphere).
The above are the basic operations for installing solar energy at home. It is recommended to consult a professional when installing and purchasing, and choose the appropriate equipment according to the family situation.
In our actual calculation, solar panels can be used for more than 20 years. As for inverters, they are fixedly installed at home and have a very long service life.
So regarding the issue raised by some readers and netizens that it is not cost-effective. Well, how to put it? In the long run, it's definitely a good deal. However, after all, installing a solar power supply system, with the air conditioner blowing but the electricity meter not moving, that's fine. The sense of achievement from the sun cannot be concealed by a little investment. Moreover, in some special areas such as farms and grasslands, green electricity can indeed bring great convenience.
