Grid-Intertied System

Grid-Intertied Solar Power SystemThe grid-intertied or utility-connected system is probably one of the most popular and common systems for those having access to the grid or a utility service provider.

The diagram to the left, shows some of the main components and the basic configuration for this type of setup.

Basically, what happens here, is that you install a photovoltaic (PV) system at your house, which is connected to your household electrical system. However, you are also connected to the power grid through your electric meter. When your solar panels are generating more electricity than you need, it is fed back into the grid and it is like your electric meter is running backwards. At times when your solar panels are not generating enough power to meet your needs, then your meter is running forwards and you are using electricity from your electric provider.

This approach helps you reduce your monthly electric bill, but also provides you with the stability of always having the amount of electricity that you need, regardless of varying weather conditions that may affect the efficiency or electric output of your PV panels.

Solar Components

common solar componentsThis diagram shows the basic concept involved in converting sunlight to electricity by using Photovoltaic (PV) solar panels.

The solar panels collect sunlight and convert it into DC electricity, which flows through wires to batteries where it is stored until it is needed. The electricity generated by the solar panels flows through a charge controller, which cuts off the flow when the battery bank is full, so that the batteries are not overcharged.

For any appliances that use DC electricity, they can draw it directly from the batteries. However, most household appliances use AC electricity, so the the DC electricity generated from our solar panels will need to flow through an inverter to supply the AC electricity for common use.

Depending on the complexity of your home solar power system there could be additional pieces of equipment, which provide safeguards, and you may not have a charge controller or battery bank if you are tied to the grid and don’t plan to store power that was generated during the day for use at night. A brief description of some common solar energy components follows:

Solar Panel or Array – Made up of multiple photovoltaic (PV) cells, these PV panels capture the sunlight and create electricity. The type of electricity that is created is direct current (DC) or battery power. Solar panels are rated in watts. Normally, this rating represents the maximum power they can generate under ideal conditions. Based on your power needs and the rating of your panels you will be able to tell how many panels are needed in your system.

Array DC Disconnect – This component is important for safety purposes. When performing maintenance on the system, it is used to shut off the power coming from the solar panels.

Charge Controller – This piece of equipment protects your batteries from being overcharged and can help to extend the life of your batteries. When your battery bank is fully charged it will cut off the charging process. However, if your system doesn’t use batteries and store¬† backup power, then its not needed.

Battery Bank – Like the charge controller just mentioned, this would be used on systems that store backup power in batteries. The batteries used for home solar systems are deep cycle batteries like those used on golf carts, boats, RV’s, fork lifts, etc… They are not the same as a common car battery.

Main DC Disconnect – This component is placed between the batteries and the inverter and it’s main purpose is to allow you to disconnect the inverter when doing maintenance. It is another safety device that is common in many home solar systems.

Inverter – Alternating current (AC) is what most household appliances run on, so the inverter turns the direct current (DC) generated by the solar panels or coming from stored power in the battery bank, into usable electricity for your home.

Generator РTypically  these run on gas or diesel fuel and are more common for off-grid sites. The generator provides a backup source of electricity when needed. This could be needed if cloudy weather prevents enough power to be created or if you are performing maintenance on your system.

AC Breaker Box or Panel – This would be the normal breaker box found in homes or cabins where your electric service provider connects to your home wiring system. Normally this would be installed and set up by a qualified electrician.