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Are there any key elements for solar power calculation/design?

The key elements involved in solar power calculation. This will directly affect your purchase price, usage situation, and after-sales cost.

Perhaps you have consulted several solar equipment suppliers and obtained various prices.

After carefully selecting and ordering a solar system, it was suddenly discovered after the installation. Why so little power generation?

Why is the battery backup time so short? Or the solar inverter cannot output power to your home load or other industrial equipment. Read this article and you will solve these problems.

Are there any key elements for solar power calculation/design?

Solar Power Calculation Key Element 1: What is the output-input voltage?

Renewable energy generation systems aim to provide sustainable electricity.

If even the most basic functions cannot be achieved, other calculations, designs, configurations, etc. Are all empty talk.

The solar system’s DC/AC voltage output must be compatible with your equipment.

The input voltage is electricity generated by solar panels or wind turbines. This electricity is input into the battery pack, and then through the inverter to your load.

In addition, for the input voltage of the hybrid and off-grid solar energy storage system, a deeper explanation is that when the battery is insufficient at night, the electricity input by the city’s main power supply is used as a supplement.

The solar solution has 3 working modes


A customer once purchased a 5kw solar energy storage system with 220vac output voltage.

It wasn’t until the system was connected to the local government power grid that realized that local power grid voltage is 110vac/220vac dual voltage.

Which means this 5kW solar system cannot allow the 110vac/220vac government grid to replenish the battery pack at night.

The system also doesn’t offer automatic switching to city mains when the battery dies.

The result is that when you wake up hot from sleep, the air conditioner is already turned off.

Because the battery pack of the solar system is insufficient. Without a cool environment, your life experience is extremely poor.

How do we solve it?

Before ordering any photovoltaic/wind power generation system, we need to measure the AC voltage in our area.

Prevent delivery of solar systems that are not compatible with the city grid. — Click the orange text to view the operation video of measuring the regional voltage.

How to measure the ac voltage in your area?-PVMARS

Different output voltages will also make solar inverters have various prices, just like the Panama customer in this case uses a dual-output 110vac/220vac inverter.

Solar Power Calculation Key Element 2: Without a utility grid, is there no output voltage adaptation problem?

The solar system inverter output is directed at your household load/industrial and commercial equipment.

Without the city’s main power supply, the PVMars energy storage system design does not include the AC input interface.

But the AC voltage at the output must be compatible with your existing load.

At this time, it is necessary to check the power labels of all loads/equipment, such as the microwave oven load in the figure below.

power label for solar power calculation

If the rated voltage is 220v-240v, then the output voltage of the PVMars solar hybrid inverter is set to 220vac, which can fully satisfy the normal operation of this microwave oven.

Because the output AC wave will have a range, normally there will be fluctuations of ±5%-10%.

You can also see how much power it needs from the power label of the load.

The PVMars 1kw-15kw product page comes with a detailed load power list. If you don’t know your load, you can click the orange font to jump to the product page.

Understand the content of the relevant tables, and judge which type of solar energy system is more suitable for your needs.

Perhaps you have noticed that there are two types of power on the microwave load power label above, input-rated power and output-rated power.

That is about Part 3 on the key elements of solar power calculation. Read on.

Solar Power Calculation key element 3: Is your device a capacitive or inductive load?

Let’s take household loads as examples: electric lights, fans, microwave ovens, televisions, air conditioners, refrigerators, induction cookers, fax machines, water pumps, etc.

The capacitive load is a relatively stable inductance, and it needs as much electricity as the rated power.

Generally speaking, only one type of power information can be filled on the power labels of electric lamps, fans, televisions, induction cookers, and fax machines.

The inductance of inductive loads will fluctuate, especially when you start the device for a moment (within about 3 seconds), it will be 3-10 times higher than the rated power.

For example, the air conditioner power label is shown in the figure below.

The red long frame is the minimum current: 12A

The green long frame frames the rated voltage of the air conditioner: 115V

According to the physical formula, P=IU=12A x 115V = 1380W

Do you think it is enough to configure a 1.5kW-2kW energy storage system?

Please note: Air conditioners, refrigerators, water pumps, and other equipment have built-in motors, and compressors are all inductive loads.

The blue long frame frames the start-up current of the air conditioner compressor motor: 47A and the power required for instant start-up reaches 5405W.

The 2000W solar system will be instantly impacted by this powerful current, causing damage.

PVMars energy storage experts are professional and flexible. They will design your own solar system according to your actual load and usage.

PVMARS VFD solve your inductive load startup problem
This instantaneous current generally only lasts for a few seconds, so we only need to design a VFD or increase the power of the solar hybrid inverter.

Just like our 5kW wind-solar hybrid installation in the Philippines, VFD is also used to reduce the impact brought on by electrical equipment. — You can click the orange font to learn more about VFDs.

Also, we noticed that the microwave oven power label has a 220v-240v voltage rating.

But the air conditioner is 115 vac. There are two kinds of AC voltages, which require special dual-output inverters to adapt.

Dual output inverter-pvmars

The air conditioner mentioned above is 1-PH/single-phase.

If it is three-phase voltage, you need a three-phase inverter for your solar system.

What is single-phase and three-phase voltage? — You can check the case of PVMars’ 30kW renewable energy system installed in Turkey to learn more.

On the market, there are many kinds of inverters with AC output. The internal structure and quality are different, which is one of the reasons for the solar energy systems’ price difference.

Stronger IGBT Inverter from PVMars solar

Depending on the situation, different inverters exert different values.

PVMars can provide conventional system configurations, but do you really need them?

Let’s move on to the 4th key element of solar computing and design.

Solar Power Calculation Key Element 4: Why Are Solar Panels Low in Power Generation? Short battery backup time?

PVMars professional engineers will design the number and capacity of solar panels and batteries according to your load and start-up time.

Assuming your air conditioner will be on for 8 hours, based on the minimum current of 12A on the power label, it will take about 11kWh.

Added the power consumption of other loads, if the total needs are 20kWh a day, will 36 pcs of 550W solar panels be needed in the end?

The answer is wrong.

PVMars solar-panel-price-philippines-1-1
We have overlooked one point, which is the average amount of sunshine, and solar panels need to absorb solar heat to generate electricity.

From the perspective of people in a certain area, the sun rises at 6 am and sets at 6 pm. There are 12 hours of sunshine between.

This is the sun-filled time for the human senses.

We can click the picture below to jump to the data page and enter the latitude and longitude or address of our area.

Local average sunshine times can be clearly determined. Generally speaking, the highest light areas are in the Middle East, with 6 hours of sunshine.

In most areas, there are only 4 hours of sunshine.

If we calculate your solar panels according to 12 hours of sunshine, it may happen that the problem of low power generation/power generation is not enough for you.

We need to face up to the sunshine time and calculate based on the average sunshine time of 4 hours. In order to ensure that the power generation of your solar system meets your needs.

Finally, about the battery.

There are many types of lithium batteries on the market, but not all lithium batteries are suitable for solar systems — this article will answer your questions about the range of solar systems that different types of lithium batteries are suitable for.

Each battery has DOD, and the DOD of lithium battery is as high as 90%-95%

We ensure that the battery pack in the solar system, backup time matches the night running time of the load.

As in the case of this solar system installed in Papua New Guinea, refer to how it is calculated.

Final words:

Combining these 4 key elements of solar computing that are most easily overlooked by everyone, you will get a 100% match for your solar, wind, and other renewable energy power generation systems.

PVMars would rather invest a lot of manpower in the early stage to build a photovoltaic energy storage system with high adaptability for you.

We do not want you to waste more money and time because of after-sales problems.

Everyone’s time is precious, after reading this blog, contact our energy experts to provide you with a complete solution.

About the author
Mr. Liu is an experienced engineer of PVMARS with in-depth research on photovoltaic and wind energy aspects. As an excellent solar installer, he has always been passionate about all aspects of domestic and industrial and commercial solar projects.

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PVMARS Solar will set up 120 energy user service centers around the world. It will provide on-site investigation, design drawings, solar energy storage system solutions, transportation of goods, assist you to import solar energy storage system, installation services, and continue to cooperate with local engineers, exclusive agents and foreign merchants.

We sincerely hope to work with like-minded partners. Win-win cooperation to achieve harmonious coexistence between mankind and nature.

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