Here are design tips for methods of PV system utility interconnection. The purpose of this article is to give you a basic understanding of the concepts and rules for connecting a solar panel system to the utility grid and the household electrical box or meter. The utility connection for a PV solar system is governed by the National Electrical Code (NEC) Article 690.64. Always refer to the NEC code in effect or consult a licensed electrician for safety and accuracy.
There are two basic approaches to connecting a grid-tied solar panel system, as shown in the wiring diagrams below. The most common is a "LOAD SIDE" connection, made AFTER the main breaker.
The alternative is a "LINE OR SUPPLY-SIDE" connection made BEFORE the main breaker.
In simple terms, a Load Side connection is made AFTER the main breaker in the electrical panel; this is the most common method of connecting. A new circuit breaker(s) will be added to the electrical panel. The circuit breaker will be dual-pole or double-space, and it will be located in a position farthest from the main breaker. Then the wires from the PV solar system will be connected to this new solar breaker. An adequately sized PV service disconnect box must be used before making the connection. Some inverters include the disconnect or an external disconnect can be added cheaply.
When using a load-side connection, two NEC rules govern the size allowed based on the electrical panel size and the solar output size. Both rules must be satisfied to meet Code when using a load-side connection.
RULE 1Known as the 120% rule, the solar circuit breaker can be no more than 20% of the main electrical panel rating. The electrical panel rating Amps (A), or Busbar rating, is the manufacturer rating typically found on a label. The circuit breaker is technically called an Over Current Protection Device, or OCPD.
Now, the main breaker can be changed to a smaller size (e.g. de-rated) to make room for more solar. Here is an example of a de-rated electrical panel to handle a larger solar system:
RULE 2The solar breaker OCPD must be at least 125% of system output. System output is determined by the total output Amp rating of the inverter(s).
It may not be possible to meet the NEC interconnection rules for older, smaller, or full electrical panels, e.g. 100A or 125A, with a larger PV solar array. You may have the option to replace the existing electrical panel with a new, larger box, or use the alternative Line Side Connection. For quick reference, you can also view this table showing the Maximum Connected PV Inverter Watts for various breaker box amp ratings.
As with most things electrical, there are many ways to do the job. There is an ALTERNATIVE UTILITY CONNECTION called a “Supply or Line Side" connection. This connection is made BEFORE the main breaker. A junction box is added between the utility meter and the main service panel. Then the wires from the utility meter, the main breaker panel, and the PV solar are connected in the junction box.
However, this approach can not void the UL certification of the main panel and will need approval by the local AHJ building authority and the utility. Some jurisdictions do not allow a supply-side connection. The AHJ may argue that a supply-side connection made inside the meter/panel enclosure, may void both the UL listing and the manufacturer’s warranty for the existing service panel. Although it is possible to overcome these issues, these AHJs have gone with a better-safe-than-sorry approach, banning supply-side connections altogether.
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Home » Renewable Energy » Grid-Connected Solar Photovoltaic (PV) System
In this easy to read guide, we will break down how to design and install a grid tied solar system including solar panels, racking, batteries, inverter and many more.
Here we go.Basic Grid Tied System Diagram
A basic grid tied system is the most common system installed in locations where electricity are already available from the local utility company.
Cutting electrical bill is the number 1 reason why we do this.
Collects Sunlight Energy - This type of system takes the energy from the sun during the day (Assume peak sunlight hours), and uses it REAL TIME for your RV, home or other facilities.
Get Credit For Left Over Power - Any left over power will be sold to the city power grid for credit.
Buy Grid Power - If sunlight isn''t enough to generate the solar power you need, then you can buy power using the credit from the grid.
You can pay a local service to do this for you, or you can design it yourself.
Here are 8 questions you must ask before starting this project:Determine monthly power usageCalculate the annual daily averageAnalyze Insolation Maps for solar potentialCalculate solar array wattagePick out solar panels to buySize an inverterIdentify string sizingDetermine mounting platformsSize breakers and fusesThe Easiest Way To Determine Your Home''s Power Usage
Look at your electric bill for the past 12 months and take into account all whether trends for an accurate estimation.
How much solar power you need to power a house? the math all starts right hereCalculate monthly power usage
For this example, we assume the following: Annual power usage: 19120 kWh,Location: Las Vegas, NVAnnual sunlight averagefor Vegas: 6.4 hrsSystem Loss: 21%
Let''s get started
First we have to calculate the annual daily average
Annual Daily Average – 19120 kWh / 365 days = 52.38 kwh / day
To see more examples, please check out this guide.
The next step is to take this number to size your solar panel required!
The insolation map will show you the regions of the world exposed to the most amount of sunlight.
It shows the visitor an average 3 - 6 peak sun hours every day and the lowest sun exposure region.
Get the annual average sun peak hours from this chart
Cities like Honolulu, Phoenix and Las Vegas do get a lot of sunlight, but northern states still get enough sunlight on average to still leverage solar power.
When we size our solar array for a grid-tied system, we are designing the requirement around the annual average number, and the maximum average for max sun exposure.
If you follow the chart, the chart will tell you if you need an roof tilt mount for your solar panels for not.
Nothing in the real world is consistent, so we need to take system inefficiency into account for a grid system.
Generally there are roughly 18 - 21 % loss in the system due to:WiringComponent qualitiesShadingSun exposureDiodesVoltage dropDetermine Solar Panel Size Required
If we follow the example aboveAnnual Daily Average = 52.38 kwh / day, that''s about 52380 W annual averageAnnual Region Average = 52380 Wh / 6.41 hrs = 8171 WOffset Loss = 8171 W / 0.79 = 10343 W
10343 W total solar panel output is needed!
Here is the important part to factor in:
Most grid tie systems aren''t 100% solar, we just want to cut our electric bill.
So we are going to cut the 10343 W number in half in this example.
10343 W / 2 = 5171 W
You can check out our best solar panel guide to select
Now let''s use this number to size the rest of our system, we go after inverter first.Size Solar Panel Inverter
The size of the grid-tied inverter is based on the size of the solar panel. There are certain numbers of panels in series or parallel connection that will work with the inverter.
The inverter converts DC power from the solar panel to AC power, and the easiest way to understand how to size it is look at how much power you consume.
For example: 4000 W consumption, please use an inverter with continuous watts and surge watts rating slightly bigger that.
Learn More: How to size solar inverter in depth
To make this easy, we use a string sizer to determine what we need.
Most inverter companies have this simple to use calculator on their websites to help the buyers make buying decisions.
Click here to learn how to configure the calculator.
Once you know which inverter you need, we figure out the mounts needed for your solar panelsDetermine Mounting System
Solar panel mounting design can differ from people to people.
If your roof is ready for it, you can hire professionals to design the mount for you.
Over current protection prevents cataphoric things from happening.
For a grid-tied system, there are two locations to install over current protection
About Grid tied solar system diagram
As the photovoltaic (PV) industry continues to evolve, advancements in Grid tied solar system diagram have become critical to optimizing the utilization of renewable energy sources. From innovative battery technologies to intelligent energy management systems, these solutions are transforming the way we store and distribute solar-generated electricity.
When you're looking for the latest and most efficient Grid tied solar system diagram for your PV project, our website offers a comprehensive selection of cutting-edge products designed to meet your specific requirements. Whether you're a renewable energy developer, utility company, or commercial enterprise looking to reduce your carbon footprint, we have the solutions to help you harness the full potential of solar energy.
By interacting with our online customer service, you'll gain a deep understanding of the various Grid tied solar system diagram featured in our extensive catalog, such as high-efficiency storage batteries and intelligent energy management systems, and how they work together to provide a stable and reliable power supply for your PV projects.
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