Solar Energy

Solar Energy

Introduction: 

Solar power is a form of energy harnessed from the power of the sun's rays. The most common way of harnessing energy from the sun is through photovoltaic (PV) panels – those large, mirror-like panels you've likely seen on rooftops, handheld solar devices, and even spacecrafts. You can power your house by a simple photovoltaic (PV) installation, and also you can earn money by using on solar system.

The most common solar systems are:

•     Off Grid Tied
•     On Grid Tied

Off-Grid Tie Solar System

An off-grid solar system (off-the-grid, standalone) is the obvious alternative to one that is grid-tied. For homeowners that have access to the grid, off-grid solar systems are usually out of question. Here`s why:

To ensure access to electricity at all times, off-grid solar systems require battery storage and a backup generator (if you live off-the-grid). On top of this, a battery bank typically needs to be replaced after 10 years. Batteries are complicated, expensive and decrease overall system efficiency When some people first consider installing solar panels on their properties, their motivation is to live independently from the power company. Off-grid solar is the setup they're thinking of, as perhaps its greatest draw is that you'll receive no bill from the power company. This can be especially beneficial in remote locations, where installing traditional power poles requires a huge investment. By installing an off-grid solar system, you don't have to worry about whether the closest power company can extend its reach out to where you live.

Others choose this option because of energy-consciousness. Put simply, in producing all of your own power supply you can understand exactly how much power you consume in a given day. This method also eliminates the inefficiencies of distribution and allows the user not to feel responsible for the power company's environmental footprint, for example, as well as their own. In other words, off-grid power represents local sourcing to the extreme.

Advantages of Off-Grid Solar Systems

1. 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 you’re more than 100 yards from the grid. The costs of overhead transmission lines range from $174,000 per mile (for rural construction) to $11,000,000 per mile (for urban construction).

2. Become energy self-sufficient

Living off the grid and being self-sufficient feels good. For some people, this feeling feeling is worth more than saving money. Energy self-sufficiency is also a form of security. Power failures on the utility grid do not affect off-grid solar systems.

On the flip side, batteries can only store a certain amount of energy, and during cloudy times, being connected to the grid is actually where the security is. You should install a backup generator to be prepared for these kinds of situations.

Equipment for Off-Grid Solar Systems

Typical off-grid solar systems require the following extra components:

• Solar Charge Controller

• Battery Bank

• DC Disconnect (additional)

• Off-Grid Inverter

• Backup Generator (optional)

Solar Charge Controller:

Solar charge controllers are also known as charge regulators or just battery regulators. The last term is probably the best to describe what this device actually does: Solar battery chargers limit the rate of current being delivered to the battery bank and protect the batteries from overcharging.

Good charge controllers are crucial for keeping the batteries healthy, which ensures the lifetime of a battery bank is maximized. If you have a battery-based inverter, chances are that the charge controller is integrated. 

Battery Bank:

Without a battery bank (or a generator) it’ll be lights out by sunset. A battery bank is essentially a group of batteries wired together.

DC Disconnect Switch:

AC and DC safety disconnects are required for all solar systems. For off-grid solar systems, one additional DC disconnect is installed between the battery bank and the off-grid inverter. It is used to switch off the current flowing between these components. This is important for maintenance, troubleshooting and protection against electrical fires.

Off-Grid Inverter:

There`s no need for an inverter if you`re only setting up solar panels for your boat, your RV, or something else that runs on DC current. You will need an inverter to convert DC to AC for all other electrical appliances.

Off-grid inverters do not have to match phase with the utility sine wave as opposed to grid-tie inverters. Electrical current flows from the solar panels through the solar charge controller and the bank battery bank before it is finally converted into AC by the off-grid-inverter.

Backup Generator:

It takes a lot of money and big batteries to prepare for several consecutive days without the sun shining (or access to the grid). This is where backup generators come in.

In most cases, installing a backup generator that runs on diesel is a better choice than investing in an oversize battery bank that seldom gets to operate at its full potential. Generators can run on propane, petroleum, gasoline and many other fuel types.

Backup generators typically output AC, which can be sent through the inverter for direct use, or it can be converted into DC for battery storage.

On Grid-Tied System

Grid-tied, on-grid, utility-interactive, grid intertie and grid back feeding are all terms used to describe the same concept – a solar system that is connected to the utility power grid.

Some—particularly businesses that require a lot of power to operate—see the fact you can rely on the power company when you require additional electricity as the main draw to grid-tied solar. For others, it's the fact that you can sell power back to the grid. The goal in doing so is to offset the cost of the power you purchased, or simply to sell any excess power you have produced to the power company after you've taken what you need within a given time frame (typically monthly). This process is called net metering, where you can save money and potentially even make a bit more. In addition to the financial aspect, some find it an attractive choice because of its benefit to the community as a whole.

Grid-tied solar often has fewer upfront costs than an off-grid system. For one, it can cost less to install a grid-tied system because it does not require batteries, as off-grid does. For another, it's more flexible, as you don't necessarily have to install the number of panels you will need to produce all your energy needs right away.

Advantages of Grid-Tied Systems

1. Save more money with net metering

A grid-connection will allow you to save more money with solar panels through better efficiency rates, net metering, plus lower equipment and installation costs:

Batteries, and other stand-alone equipment, are required for a fully functional off-grid solar system and add to costs as well as maintenance. Grid-tied solar systems are therefore generally cheaper and simpler to install.

Your solar panels will often generate more electricity than what you are capable of consuming. With net metering, homeowners can put this excess electricity onto the utility grid instead of storing it themselves with batteries.

Net metering (or feed-in tariff schemes in some countries) play an important role in how solar power is incentivized. Without it, residential solar systems would be much less feasible from a financial point of view.

Many utility companies are committed to buying electricity from homeowners at the same rate as they sell it themselves.

2. The utility grid is a virtual battery

Electricity has to be spent in real time. However, it can be temporarily stored as other forms of energy (e.g. chemical energy in batteries). Energy storage typically comes with significant losses.

The electric power grid is in many ways also a battery, without the need for maintenance or replacements, and with much better efficiency rates. In other words, more electricity (and more money) goes to waste with conventional battery systems.

According to EIA data, national, annual electricity transmission and distribution losses average about 7% of the electricity that is transmitted in the United States. Lead-acid batteries, which are commonly used with solar panels, are only 80-90% efficient at storing energy, and their performance degrades with time.

Additional perks of being grid-tied include access to backup power from the utility grid (in case your solar system stop generating electricity for one reason or another). At the same time you help to mitigate the utility company`s peak load. As a result, the efficiency of our electrical system as a whole goes up.

Equipment for Grid-Tied Solar Systems

There are a few key differences between the equipment needed for grid-tied, off-grid and hybrid solar systems. Standard grid-tied solar systems rely on the following components:

• Grid-Tie Inverter (GTI) or Micro-Inverters

• Power Meter

• Power Bank (optional)

 

Grid-Tie Inverter (GTI):

What is the job of a solar inverter? They regulate the voltage and current received from your solar panels. Direct current (DC) from your solar panels is converted into alternating current (AC), which is the type of current that is utilized by the majority of electrical appliances.

In addition to this, grid-tie inverters, also known as grid-interactive or synchronous inverters, synchronize the phase and frequency of the current to fit the utility grid (nominally 60Hz). The output voltage is also adjusted slightly higher than the grid voltage in order for excess electricity to flow outwards to the grid.

Micro-Inverters:

Micro-inverters go on the back of each solar panel, as opposed to one central inverter that typically takes on the entire solar array.

There has recently been a lot of debate on whether micro-inverters are better than central (string) inverters.

Micro-inverters are certainly more expensive, but in many cases yield higher efficiency rates. Homeowners who are suspect to shading issues should definitely look into if micro-inverters are better in their situation.

Power Meter:

Most homeowners will need to replace their current power meter with one that is compatible with net metering. This device, often called a net meter or a two-way meter, is capable of measuring power going in both directions, from the grid to your house and vice versa.

You should consult with your local utility company and see what net metering options you have. In some places, the utility company issues a power meter for free and pay full price for the electricity you generate; however, this is not always the case.

Battery Bank (optional):

Without a battery bank (or a generator) it’ll be lights out by sunset. A battery bank is essentially a group of batteries wired together.