How to design solar photovoltaic(PV) system

solar photovoltaic(PV) system design.

Chapter 4 of 【Solar PV System Design 】series:How to Design Solar PV System.

It might be quite challenging for a novice solar user to figure this whole solar pv system.However, it only needs to pass the following 6 steps to help us complete the solar photovoltaic system design.

1.Know the components of a solar PV system

Strings of solar panels connected in series produce high Voltage direct current (DC) from sunlight. The charge controller (also called an MPPT) converts this to a lower Voltage and either sends it to an inverter for immediate use or stores it in a battery bank. The inverter converts DC from the battery bank to the alternating current (AC) used in your appliances. Read 【Solar PV System Design :1 】What is a solar PV system ? to learn the detail information of a solar PV system?

2.Сalculate your home electricity usage

To become truly energy independent with a new solar PV system, you need to assess the amount of energy it will have to produce. Depending on your circumstances, the best approach will be one of the following.

  • Calculate your daily load manually:Make a list of all the devices you use daily, find out their power ratings and multiply by the time you normally use them a day. Sum everything up to get your average energy consumption
  • Look at your electricity bill for average usage:the most rational and time efficient. They will tell you the average energy consumption per month.
  • Ask a solar installation company to do it for you:Solar companies can combine peak sunshine hours in your area with in-person roof assessments to develop the most accurate projection of solar panel production

Read calculate solar system size for your home to  learn How to calculate solar system size for your home.

3.Determine the type of solar photovoltaic system

There are several types of solar power systems: grid-tie, off-grid and hybrid.

  • Grid-tie solar systems: also referred to as on-grid, utility-interactive, grid intertie or grid backfeeding, are popular with both homes and businesses.
  • off-grid solar systems:Many homeowners prefer to install that to become completely energy independent. The thing is that off-grid solar systems aren’t connected to the electricity grid, so they will continue working even if the public power grid is not functioning.
  •  hybrid system: can do both;Despite the fact they are connected to the utility grid, they have extra battery storage as a backup.

If you choose a grid-connected solar system,you need two main component : solar panels and an inverter.If you decide to go off-grid, it will require an investment in one more components : a battery.

It should be noted that this article directly explains the installation of off-grid solar energy systems.Grid-tie solar systems, also referred to as on-grid, utility-interactive, grid intertie or grid backfeeding, are popular with both homes and businesses. They are connected to the utility power grid, which is necessary to run the PV system. You’ll have to check with your local utility

There are three major parts of a off-grid solar PV system design: (1) solar panels, (2) charge controllers and inverters, and (3) batteries.Each of these design choices will be described in a later section.

4.calculate solar system size for your home

The number of solar panels you’ll need

500W 540W solar panels 1

Let’s take  average U.S. home uses about 900 kWh per month. that’s  the average 30 kWh per day  .With 4.5 peak sun hours in U.S, the family will need a solar panel system with a capacity of  6.8KW.You will not have access to the full DC output of your solar panels; that’s because all solar power systems experience system losses.So, you should choose to install a solar PV system around 7 kW.

Such a system could consist of sixteen 450 watt solar panels or twelve 600w solar panels. If you have a small or unusually shaped roof, solar panel size and numbers are important considerations. With a large usable roof area, perhaps you can sacrifice some efficiency and buy larger panels (at a lower cost per panel) to get to your target energy output. But if your usable roof area is limited, or if it’s partially shaded, being able to use fewer smaller high-efficiency panels may be the best way to make the most possible power over the long term.

Inverter sizing

An inverter is the heart of a solar electric system. The inverter converts the direct current (DC) that is coming from solar panels or from a battery into the alternating current (AC) that is used by the appliances in your home.

String Inverters: What You Need To Know

There are three types of solar inverters:

  1. Off-grid inverters make their own AC sine wave by converting DC Voltage in a battery bank. As long as there is enough Voltage in the battery bank, the off-grid inverter will run.
  2. Grid-tied inverters: allow for two-way communication between the inverter and the electrical utility. This can help balance supply and demand either automatically or via remote communication with utility operators. Allowing utilities to have this insight into (and possible control of) supply and demand allows them to reduce costs, ensure grid stability, and reduce the likelihood of power outages.
  3. Hybrid inverters: are just these 2 types of inverters placed together in the same box. You can accomplish the same thing using manual or automatic transfer switches.
For stand-alone systems, the inverter must be large enough to handle the total amount of Watts you will be using at one time. The inverter size should be 25-30% bigger than total Watts of appliances. In case of appliance type is motor or compressor then inverter size should be minimum 3 times the capacity of those appliances and must be added to the inverter capacity to handle surge current during starting.
For grid tie systems or grid connected systems, the input rating of the inverter should be same as PV array rating to allow for safe and efficient operation.
Battery sizing
Most solar production takes place between 9 a.m. and 3 p.m., but your electric demand takes place throughout the 24-hour day. For a solar PV system, night refers to the 16 to 18 hour period when you are making little or no solar power. If you are grid-tied, you are relying on the grid to power all of your appliances during this period. If you have any type of battery backup, the batteries store the excess power made during the day so that it can be used at night. Additional batteries are necessary if you want more days of autonomy to carry you through periods of low solar production.
Battery sizing depends on your estimate of how many Kilowatt-Hours per Day (KWH/day) your system will use. This is the basis of your system’s design. It also depends on how many Kilowatt-Hours (KWH) you use at night, as defined above. Most people use about half of their total daily use at night. For example, a  home using 30 KWH/day should have about 15 KWH of battery capacity to go through the night if they are totally off-grid. Since each of our 5.12 KWH Lithium Iron Phosphate batteries provides 4.1 useable Kilowatt-Hours (KWH), 4 batteries can satisfy the needs of the family. Customers who use a higher proportion of their daily power demand at night, and those who want more days of autonomy, will need more batteries.
Solar charge controller sizing
The solar charge controller is typically rated against Amperage and Voltage capacities. Select the solar charge controller to match the voltage of PV array and batteries and then identify which type of solar charge controller is right for your application. Make sure that solar charge controller has enough capacity to handle the current from PV array.
Today, virtually all grid-tied inverters and many off-grid inverters include charge controllers. Our stackable off-grid inverters are designed so that you will not need a separate charge controller, even if your system is large.If you are off-grid and need more charging capacity than the inverter(s) provide, a separate charge controller can provide additional Amperage to charge the batteries.

WinSeven Solar  supplies all the necessary items for residential and commercial PV systems.WinSeven Solar has a variety of inverters ready for use in both grid-tie and off-grid systems and e have 50w-600w single-crystal or polycrystalline,Bificial or Monoficial solar panels with different power.Read Different solar panel types to learn How to Choose the right Solar Panels:Mono or poly , N Type or P Type,Bificial or Monoficial…


It is the final step, but not necessarily the one you want to make on your own,you can hire a professional installer to help you with this.If t you choose  a grid-connected solar system you need to contact a professional anyway. Only a certified expert can connect your system to the public grid.

However, if you think isn’t difficult and  have any assistant,you can learn the following and install it yourself manually.

  1. mounting structure:PV arrays must be mounted on a stable, durable structure that can support the array and withstand wind, rain, hail, and corrosion over decades. These structures tilt the PV array at a fixed angle determined by the local latitude, orientation of the structure, and electrical load requirements. To obtain the highest annual energy output, modules in the northern hemisphere are pointed due south and inclined at an angle equal to the local latitude. Rack mounting is currently the most common method because it is robust, versatile, and easy to construct and install. More sophisticated and less expensive methods continue to be developed.
  2. solar panels weigh:Knowing a solar panel’s weight is the best way to be certain that your roof can support a full installation.
  3. And other issues….

Following these 6 steps you can make your solar panel system from scratch.If you have any questions or need to buy solar PV system, please feel free to contact us.