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Solar Panel System (PV Photovoltaic)

How Small Solar Electric Systems Work

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Solar electric systems, also known as photovoltaic (PV) systems, convert sunlight into electricity.

Solar cells—the basic building blocks of a PV system—consist of semiconductor materials. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms. This phenomenon is called the "photoelectric effect." These free electrons then travel into a circuit built into the solar cell to form electrical current. Only sunlight of certain wavelengths will work efficiently to create electricity. PV systems can still produce electricity on cloudy days, but not as much as on a sunny day.

The basic PV or solar cell typically produces only a small amount of power. To produce more power, solar cells (about 40) can be interconnected to form panels or modules. PV modules range in output from 10 to 300 watts. If more power is needed, several modules can be installed on a building or at ground-level in a rack to form a PV array.

PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day.

Because of their modularity, PV systems can be designed to meet any electrical requirement, no matter how large or how small. You also can connect them to an electric distribution system (grid-connected), or they can stand alone (off-grid).

Grid-Tied Solar PV Calculator

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Grid-Tied Solar Photovoltaic (PV) Systems

If your building is already connected to the power network or a connection to the national grid would be easy and not too expensive to arrange, a Grid-Tied Solar Photovoltaic system is often the most cost effective PV System to install.

A Grid-Tied PV system offers the potential to make a profit on the energy you generate, whilst significantly reducing your energy bills and making a contribution to lowering CO2 emmissions.

Grid-Tied Solar Photovoltaic (PV) Equipment

Below is an overview of what equipment is needed in a typical Grid-Tied Solar PV installation.

 

  • Solar PV Panels / PV Modules - The head end of a PV system that converts daylight into electrical current. As well as traditional Solar Panels, Solar PV panels can also be integrated into building materials where you may have traditionally used glass such as into canopies, skylights and balconies.
  • A Grid-Tie Inverter - Is used to convert DC power into AC power ready for use and export to the grid.
  • Cables & Accessories - Used to safely connect the various components, cables should be specified in relation to the maximum load current and the potential operating temperatures.
  • Isolators - Used to disconnect parts or all of the system for maintenance and/or in an emergency.
  • Mounting System - There is a wide choice of mounting systems. Solar PV panels and moduless can be mounted onto roofs (bolted on top or integrated within) Free Standing Frames and Building Integrated PV solutions are also available.
  • Monitor - Used for measuring how much energy is being generated.
  • Export Meter - An export meter monitors how much electricity is generated in kWhrs, Most meters will also show you at a glance how much electricity is being generated at the time..

Grid-Connection Requirements from Your Power Provider

Currently, requirements for connecting distributed generation systems—localized or on-site power generation systems like small renewable energy systems—to the electricity grid vary widely. However, all power providers face a common set of issues in connecting small renewable energy systems to the grid, so you will likely encounter regulations regarding safety and power quality, contracts (which may require liability insurance), and metering and rates.

You will need to contact your power provider directly to learn about its specific requirements. If your power provider does not have an individual assigned to deal with grid-connection requests, try contacting your state utilities commission, state utility consumer advocate group (represents the interests of consumers before state and federal regulators and in the courts), state consumer representation office, or state energy office.

Metering and Rate Arrangements for Grid-Connected Systems

The Public Utility Regulatory Policy Act of 1978 (PURPA) requires power providers to purchase excess power from grid-connected small renewable energy systems at a rate equal to what it costs the power provider to produce the power itself. Power providers generally implement this requirement through various metering arrangements. Here are the metering arrangements you are likely to encounter:

  • Net purchase and sale

    Under this arrangement, two uni-directional meters are installed—one records electricity drawn from the grid, and the other records excess electricity generated and fed back into the grid. You pay retail rate for the electricity you use, and the power provider purchases your excess generation at its avoided cost (wholesale rate). There may be a significant difference between the retail rate you pay and the power provider's avoided cost.

  • Net metering

    Net metering provides the greatest benefit to you as a consumer. Under this arrangement, a single, bi-directional meter is used to record both electricity you draw from the grid and the excess electricity your system feeds back into the grid. The meter spins forward as you draw electricity, and it spins backward as the excess is fed into the grid. If, at the end of the month, you've used more electricity than your system has produced, you pay retail price for that extra electricity. If you've produced more than you've used, the power provider generally pays you for the extra electricity at its avoided cost. The real benefit of net metering is that the power provider essentially pays you retail price for the electricity you feed back into the grid.

    Some power providers will now let you carry over the balance of any net extra electricity your system generates from month to month, which can be an advantage if the resource you are using to generate your electricity is seasonal. If, at the end of the year, you have produced more than you've used, you forfeit the excess generation to the power provider.

Off-Grid Solar Photovoltaic (PV) Systems

An Off-Grid Solar PV System is self contained and uses batteries to store and release electricity when the Solar PV Panels aren't active such as at night. An Off-Grid PV solution is ideal for remote buildings, application specific functions such as for powering machinery, temporary solutions, pumps, boats, pretty much anywhere where mains electricity isn't available and or isn't needed.

Off-Grid Solar Photovoltaic (PV) Equipment

 

  • Solar PV Panels / PV Modules - The head end of the system that converts daylight into electrical current.
  • Power Inverters - Used to convert DC power provided by Solar panels and stored in batteries into AC Electricity to be integrated into the buildings electrical system.
  • Charge Controller - Used to prevent damage to batteries through overcharging and reverse current.
  • Cables & Accessories - Used to safely connect the various components.
  • Isolators - Used to disconnect parts or all of the system for maintenance and/or in in an emergency.
  • Monitor - Used for measuring how much energy is being generated.
  • Batteries - Used to store and release power.
  • Mounting System - Used to install Solar panels on a roof or other suitable structure.

Hybrid Solar Photovoltaic (PV) Systems

If you were thinking that there is nothing stopping you from having both types of system installed at the same time you would be absolutely right. A Hybrid system gives you all the benefits of both systems with the added benefits from protection from power cuts and outages (from either solar or mains), coupled with the ability to live independently of fossil fuels whilst supplying others with clean, green energy.

A Hybrid Solar PV System would utilise a connection to the grid enabling power to be exported and also use batteries to protect against power cuts and store power for use locally.

Please note that as with all grid connected PV systems, in hybrid systems we need to protect against islanding, this is where the PV system would continue to generate and export power to the grid even if the mains power was unavailable. For safety the PV system will disconnect itself from the grid if the mains power is unavailable.

Batteryless Solar Photovoltaic (PV) systems

This is where energy generated is supplied directly to appliances, think of the simple solar powered lights you can buy in shops and you get the idea. This kind of power system is common powering water pumps, road signs and electric fences.

If you are considering installing a new PV System, we will be happy to thoroughly go over all of the options available and help you figure out which is the best for you.

contact us (407) 697-3992

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