The 120% Rule And Your Main Breaker Panels Limitations
5kW grid tied solar system
The altE Store started designing and selling grid-tied solar systems way back around the year 2000. Back then, a typical solar system was about 5000W. Nowadays as the price of solar panels drops, the size of the solar array rises. A larger solar array requires a larger inverter. Now 10,000W inverters and larger that used to be reserved to commercial solar systems are now becoming commonplace in residential. Once solar inverters get larger than 7680W, installers often will run into a restriction from the National Electric Code that needs to be addressed.
This restriction has become known as the 120% rule. We are going to explain the rule, and cover ways to deal with it.
Grid Tie Solar Basics
How can you experience the freedom of electricity that is flexible, reliable and puts you in control?
The solar market is flooded with one size fits all systems, under-qualified product retailers, and promises of lottery-win investment returns. Some of the same sellers that offer do it yourself solar kits also sell garden supplies. And many contractors that provide complete solar installations give all their clients the same unimaginative options.
So what do you do when you need expert guidance to choose the right power alternative with confidence?
Schedule Your Free Consultation
Fire Mountain Solar is all about tailored solutions. When you understand the basics about power systems suited for your specific goals, you can confidently choose the option that gives you all the comfort, security and convenience you want and need, any time, anywhere.
What is Grid Tie Solar?
The straightforward grid-tied solar system is currently the most popular choice for both homes and businesses. Grid-tied simply means this type of system is connected to, and relies on, the existing utility electrical grid as an essential system component.
Payment For Injected Power
Electricity companies, in some countries, pay for electrical power that is injected into the electricity utility grid. Payment is arranged in several ways.
With net metering the electricity company pays for the net power injected into the grid, as recorded by a meter in the customer’s premises. For example, a customer may consume 400 kilowatt-hours over a month and may return 500 kilowatt-hours to the grid in the same month. In this case the electricity company would pay for the 100 kilowatt hours balance of power fed back into the grid. In the US, net metering policies vary by jurisdiction.
Feed-in tariff, based on a contract with a distribution company or other power authority, is where the customer is paid for electrical power injected into the grid.
In the United States, grid-interactive power systems are specified in the National Electric Code, which also mandates requirements for grid-interactive inverters.
You May Like: How Much Does Solar Increase Property Value
Is This Solar Panel Kit Right For Me
This 3kW microinverter based kit is great for those with small electric bills or who want to shave off a big chunk of their usage. The systems take less than 184 square feet of roof space so even a small roof should accommodate the solar modules.
The 225-500kWh generated by these systems is a good amount of energy, enough to offset most of your lighting or even you air conditioning use. The average American uses 920kWh per month. Based on that average this system could provide 24-54% of your usage. If you’re a below average consumer, a 3000W system could greatly reduce your electric bill.
Contractual Issues For Grid
When connecting your small renewable energy system to the grid, you will probably need to sign an interconnection agreement with your power provider. In your agreement, power providers may require you to do the following:
- Carry liability insurance — Liability insurance protects the power provider in the event of accidents resulting from the operation of your system. Most homeowners carry at least $100,000 of liability through their homeowner insurance policies , which is often sufficient. Be aware, however, that your power provider may require that you carry more. Some power providers may also require you to indemnify them for any potential damage, loss, or injury caused by your system, which can sometimes be prohibitively expensive.
- Pay fees and other charges — You may be asked to pay permitting fees, engineering/inspection fees, metering charges , and stand-by charges . Identify these costs early so you can factor them into the cost of your system, and don’t be afraid to question any that seem inappropriate.
In addition to insurance and fees, you may find that your power provider requires a great deal of paperwork before you can move ahead with your system. However, power providers in several states are now moving to streamline the contracting process by simplifying agreements, establishing time limits for processing paper work, and appointing representatives to handle grid-connection inquiries.
You May Like: How To Start A Sole Proprietorship In Alabama
How To Use Pv
The previous section assumed that you can mount solar panels at an ideal location: Perfectly south facing, with a great tilt-angle, and without any shading. What if your roof, or other location, is not quite that good? In most cases we can still accurately figure out what it will take to produce the kWhs needed. All we need is a little help from the US tax payers!
The US government, and NREL in particular, has created a very handy online tool that can calculate solar PV yield for any place on earth, taking orientation, angle, and even the local weather patterns such as cloud cover into account. It is called PV-Watts and clicking this link should open it up in a separate window. First we enter the location of the solar panels, or Ottawa to stick with our previous example. PV-Watts now finds the nearest location that it has weather data for, and displays that. Go to the next screen, and for our example we need to change a few parameters. The DC system size is how much solar PV you have, in kW. We want to know what each kW of panels will produce so change this to 1. The module type of Standard should be fine for most, we can also leave Array type to the default of Fixed . The system losses of 14.08% are fine too. For the Tilt we will change this to 45 degrees, the latitude of Ottawa, just like our earlier example, and the Azimuth is fine at 180 degrees .
Correction factor = PV-Watts reported yield per kW of panels / Actual yield per kW of panels
How Grid Tie Solar Works
Having a solar panel installation in the Philippines is one of the best decisions you can do for your home. Have you ever wondered how the technology behind the solar energy system works? Then, you have come to the right article.
How solar power works is fairly easy to understand and the grid tie solar component is one of the components that you should utilize. A grid tie solar electric system is also referred to as grid-tied and utility intertied photovoltaic system. This is different from an off-grid or standalone solar system, where your structure is not hooked up to a utility power.
If you are a homeowner or a business establishment owner in the Philippines, solar panel installations should be on top of your list of investments. Many case studies that utilize the solar system has spoken about the benefits that they have harvested from having them installed in their properties. Turning sunlight into electricity is a sustainable solution for your home and the environment.
Get to know how grid tie solar works and learn how it can help you in the future just continue reading below.
Recommended Reading: Where Can I Buy A Solar Battery Charger
Midnite Solar 150 Mppt Charge Controller
Midnite Solar has been around a long time. This is the charge controller we use at our house. This style comes in a variety of sizes to fit your system needs. It can be used with solar, wind, or hydropower systems. You can monitor the charge controller from your computer or Smart Phone, so you dont always have to walk to the location of the charge controller to view info. Data from your system is logged for up to 380 days. In addition, Midnite Solar charge controllers have built-in safety features such as ground fault protection and short-circuiting protection.
Just so you know, the prices listed on the company website are far higher than what you can find their products for at online solar retailers. Therefore, I advise shopping around for the best price if you intend on purchasing a Midnite Solar product.
Additionally You Will Get
For A Successful Installation
All AccessoriesOur grid-tie systems come with a pass-through box and MC4 output cables to connect the solar panels. Other accessories for a professional and code compliant installation, such a set of PV safety labels, are also included.
Permitting PackageBOXED residential systems come with a full permitting package specifically made for your project. The PDF package covers the most common permitting requirements such as roof layout, electric line diagram, electrical specifications and product data sheets.
Certified SupportBesides the downloadable installation manuals provided by the equipment manufacturers, our champion staff, which includes NABCEP-certified engineers, will be always available to help you with your project.
Are you aware of your city requirements for solar installations?Learn what the typical Solar Permitting Process looks like and the first steps you can take to get started.
Don’t Miss: What Is The Average Cost Of A Home Solar System
What Are The Specifics Of A Grid
As each electrical grid is unique, and has different characteristics, the grid-tie inverter must also be adjusted to match the unique characteristics of the local grid. If the inverter is not designed correctly for the appropriate grid that it is connecting to, higher levels of voltage can overload the grid if there are enough systems connected.
Grid-tie inverters are also a safety feature at times where there is a power outage. This is a law that prevents additional voltage from your renewable energy installation to contribute to the grid, as it runs the risk of injuring the utility workers who are working to repair the system. By disconnecting all systems from distributing voltage, workers are free from high voltage situations that could cause them severe injury.
Takeaway: Summer Exports Offset High Winter Usage
A home with grid-tied solar panels will generate lots of excess solar power during the summer. The homeowner can then carry these credits over and use them during the winter, when their grid imports are higher than solar power exports.
In other words, the high solar generation over the summer serve to cancel out the relatively high imports of the winter. In fact, with a properly-designed system, a home with grid-tied solar panels can even end up with zero net electricity usage charges for the year.
Calculate how much solar panels will save you each year
Read Also: How Much Does Solar Heating Cost For A Pool
What Is A Grid
First, lets establish exactly what a grid-tied solar system is.
The simplest definition of a grid-tied solar system is one that is connected to the electrical power grid. The system is reliant on this grid to produce usable solar energy and funnel excess energy for net metering, clean energy credits, or later usage.
It may seem counterintuitive to install a solar power system that is reliant on the same energy grid youre trying to get away from, however, once you understand the facts of how a grid-tied solar system works and the benefits it provides over an off-grid system, it will make much more sense.
Choose The Right Solar Panels
If you have a small or odd-shaped roof, solar panel size is an important consideration when deciding on the size of a solar system. Take these factors into account:
- With a large usable roof area, you can buy more larger panels to get to your target energy output.
- If your usable roof area is limited or partially shaded, using fewer smaller high efficiency panels will ultimately be the most cost-effective, long-term solution. You can add more panels later on to accommodate increased energy needs.
You May Like: How Are Solar Panels Energy Efficient
How Do I Integrate A Battery Backup With A Grid
One of the most common questions asked by customers is how to integrate a battery backup solution with an existing grid-tie system. As designed and required by law, grid-tie systems shutdown during a grid power outage. To get a better understanding as to why that happens, read this article for a more detailed explanation on the subject. The main reason is to make sure solar panels are not back-feeding power into the grid while line workers are attempting to make repairs. With those details being known, customers want to maintain some level of power during a grid-outage for powering essential appliances or critical loads. Resolving that issue requires integrating a battery backup alongside your grid-tie system that does not feed power back into the grid.
In closing, AC Coupling offers a fail-safe option to power critical appliances like freezers and water pumps if grid power goes down and allows the system to back-feed the grid when grid power is active while ensuring your battery bank is fully charged.
For a more detailed explanation, watch the video below. Be sure to to be notified of more videos when we post them.
Choosing The Right Solar Panels For The Job
If youre limited on space for your DIY solar project, monocrystalline panels are the best option due to their greatest efficiency and similar cost to their polycrystalline cousins.
Polycrystalline panels may be suitable if space is not an issue and youre trying to reduce costs even in small ways.
Thin films arent suitable for small-scale solar installation projects, nor are they worth it.
Also Check: How Many Solar Panels For 800 Sq Ft Home
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.
Once you know which inverter you need, we figure out the mounts needed for your solar panels
Getting Started With Solar System Sizing
Before you begin to size a solar system, youll want to figure out the main constraints on the project and use those restrictions as the starting point for the design. You can approach the project from one of three angles:
- Budget constraints: Build a system within your target budget.
- Space constraints: Build a system that is as space-efficient as possible.
- Energy offset: Build a system that offsets a certain percentage of your energy usage.
Take into consideration other sizing factors and common stumbling blocks that may impact how to size a solar system:
Read Also: Is Leasing Solar Panels A Good Idea
Calculate The Size Of Your Solar System
To figure out how to size your solar system, take your daily kWh energy requirement and divide it by your peak sun hours to get the kW output. Then divide the kW output by your panels efficiency to get the estimated number of solar panels youll need for your system.
x 1.15 efficiency factor = DC solar system size
For example, if you live in New Mexico, you average six peak sunlight hours per day. Youll need 6.2 kW DC according to the formula:
x 1.15 efficiency factor = 6.2 kW DC solar system size required
Using the example above with a 6.2 kW DC system, you can multiply this number by 1,000 to confirm that you need 6,200 watts of solar panels.
6.2 kW x 1000 = 6200 watts solar panel required
Types Of Solar Panel Systems
What is a solar panel system?
Modern solar panel systems consist of four main components:
Solar panels, which convert sunlight into direct current electricity
A grid-tie inverter, which converts DC into AC usable energy for your home
Mounting hardware for the roof or ground
A monitoring system that offers real-time insights into your solar power system’s performance
Inverter choice should be one of the most significant factors weighing your decision. Inverter efficiency is more important than solar panel efficiency.
What types of grid-tie inverters are available?
There are three types of inverters for grid-tie solar power systems: string inverters, power optimizers and micro inverters. As you search for the right solar system for your home, its essential to choose an inverter suitable for your needs and electricity usage.
String inverters have the lowest price point but the most limitations when it comes to their traditional, dated technology and factors like shading, expansion and system monitoring. String inverters can only be used for ground mounted solar panel systems and are not allowed on roof mounted systems. Additionally, string inverters have a single point of failure. If the string inverter goes out, your entire solar system also goes down.
Don’t Miss: How Many Solar Panels For 1500 Kwh
No Access To The Utility Grid
Off-grid solar systems can be cheaper than extending power lines in certain remote areas.
Consider off-gird if youre more than 100 yards from the grid. The costs of overhead transmission lines range from $174,000 per mile to $11,000,000 per mile . SDG& E charges more when they encounter rocks or granite – common in many rural areas of San Diego, Riverside and Imperial and Orange County.