A2E Solar Grid-tie Systems

A2E Residential Grid-Tie Systems provide reliable power for your home or building using top quality UL listed products. Each system is pre-packaged to save design time and includes solar modules, UniRac® SolarMount mounting structure, inverters, cables and all necessary hardware and electrical components. The home-run wiring from the solar array to the main panel is supplied by the installer. A2E grid-tie systems are modular which means you can combine multiple units together or add to your system in the future.

A2E grid-tie systems meet NEC code requirements and US safety standards. The mounts securely attach the array to the roof in compliance with US Building Codes. Complete documentation, installation guide and operational manual included. An optional utility grade kWh meter is also available. 20-year warranty on power output and a five-year system warranty.

A2E GTS Systems employ UL listed Sharp or Sanyo solar modules - ideal for grid-tie applications. Sanyo modules have one of the highest Performance Test Condition ratings per watt (W ptc) for higher rebates in California. Performance Test Condition testing simulates the real world, high cell temperatures modules are subjected to in the field. Sharp modules offer high-powered performance, efficiency and durability for large electrical power requirements.

Please Note: GTS systems must be installed by a qualified electrical or solar contractor. GTS systems are used exclusively for the production of electricity. To size your system, use our design guide located here.

ALSO: A2E solar power systems are only designed to provide electricity to run your lights, appliances and other electric devices in your home and does not convert the sun's light directly into heat. Our solar modules convert sunlight into electricity to operate appliances, lights and other devices and will not heat water. A2E also sells solar thermal panels or systems used for water heating or passive solar heating.

Solar Basics

PV power generation systems are made up of interconnected components, each with a specific function. One of the major strengths of PV systems is modularity. As your needs grow, individual components can be replaced or added to provide increased capacity. Following is a brief overview of a typical PV system.

Solar Array: The solar array consists of one or more PV modules which convert sunlight into electric energy. The modules are connected in series and/or parallel to provide the voltage and current levels to meet your needs. The array is usually mounted on a metal structure and tilted to face the sun.
Charge Controller: Although charge controllers can be purchased with many optional features, their main function is to maintain the batteries at the proper charge level, and to protect them from overcharging.
Battery Bank: The battery bank contains one or more deep-cycle batteries, connected in series and/or parallel depending on the voltage and current capacity needed. The batteries store the power produced by the solar array and discharge it when required.
Inverter: An inverter is required when you want to power AC devices. The inverter converts the DC power from the solar array/batteries into AC power.
AC and DC Loads: These are the appliances (such as lights or radios), and the components (such as water pumps and microwave repeaters), which consume the power generated by your PV array.
Balance of System: These components provide the interconnections and standard safety features required for any electrical power system. These include: array combiner box, properly sized cabling, fuses, switches, circuit breakers and meters.

We have provided you with an easy-to-follow, step-by-step guide for sizing your photovoltaic (PV) system. Follow these five steps to determine your requirements and specify the components you will need.

1. Determine Your Power Consumption Demands

Make a list of the appliances and/or loads you are going to run from your PV system. Find out how much power each item consumes while operating. Most appliances have a label on the back which lists the wattage. Specification sheets, local appliance dealers, and the product manufacturers are other sources of information. We have provided a chart that lists typical power consumption demands of common devices which you can use as a guide. Once you have the wattage ratings, fill out the load sizing worksheet. List all of the electrical appliances to be powered by your PV system. Separate AC and DC devices and enter them in the appropriate table. Record the operating wattage of each item. Most appliances have a label on the back that lists the wattage. Local appliance dealers and the product manufacturers are other sources of this information. Specify the number of hours per day each item will be used. Multiply the first three columns to determine the watt-hour usage per day. Enter the number of days per week you will be using each item to determine the total watt-hours per week each appliance will require.

2. Optimize Your Power System Demands

At this point, it is important to examine your power consumption and reduce your power needs as much as possible. (This is true for any system, but it is especially important for home and cabin systems, because the cost savings can be substantial.) First identify large and/or variable loads (such as water pumps, outdoor lights, electric ranges, AC refrigerators, clothes washers, etc.) and try to eliminate them or examine alternatives such as propane or DC models. The initial cost of DC appliances tends to be higher than AC, but you avoid losing energy in the DC to AC conversion process, and typically DC appliances are more efficient and last longer. Replace incandescent fixtures with fluorescent lights wherever possible. Fluorescent lamps provide the same level of illumination at lower wattage levels. If there is a large load that you cannot eliminate, consider using it only during peak sun hours or only during the summer. (In other words, be creative!) Revise your Load Sizing Worksheet now with your optimized results.

3. Size Your Battery Bank

Read "Characteristics of Batteries" and then choose the appropriate battery for your needs. Fill out the Battery Sizing Worksheet.

Characteristics of Batteries

Sizing Your Battery Bank: The first decision you need to make is how much storage you would like your battery bank to provide. Often this is expressed as "days of autonomy," because it is based on the number of days you expect your system to provide power without receiving an input charge from the solar array. In addition to the days of autonomy, you should also consider your usage pattern and the criticality of your application. If you are installing a system for a weekend home, you might want to consider a larger battery bank, because your system will have all week to charge and store energy. Alternatively, if you are adding a PV array as a supplement to a generator-based system, your battery bank can be slightly undersized since the generator can be operated if needed for recharging.
Temperature Effects: Batteries are sensitive to temperature extremes, and you cannot take as much energy out of a cold battery as a warm one. Use the chart on the Battery-Sizing Worksheet to correct for temperature effects. Although you can get more than rated capacity from a hot battery, operation at hot temperatures will shorten battery life.
Depth of Discharge: Depth of Discharge is the percentage of the rated battery capacity that is withdrawn from the battery. The capability of a battery to withstand discharge depends on its construction. Two terms, shallow-cycle and deep-cycle, are commonly used to describe batteries. Shallow-cycle batteries are lighter, less expensive and have a short lifetime. For this reason, we do not sell shallow-cycle batteries. Deep-cycle batteries should always be used for stand-alone PV systems. These units have thicker plates and most will withstand daily discharges up to 80% of their rated capacity. Most deep-cycle batteries are flooded electrolyte which means the plates are covered with the electrolyte and the level of fluid must be monitored and distilled water added periodically to keep the plates fully covered. We also offer sealed, lead-acid batteries that do not require liquid refills. There are other types of deep-cycle batteries such as nickel cadmium used in special applications. The maximum depth of discharge value used for sizing should be the worst case discharge that the battery will experience. The system control should be set to prevent discharge below this level.
Rated Battery Capacity: The ampere-hour capacity of a battery is usually specified together with some standard hour reference such as ten or twenty hours. For example, suppose the battery is rated at 100 ampere-hours and a 20-hour reference is specified. This means the battery is fully charged and will deliver a current of 5 amperes for 20 hours. If the discharge current is lower, for example 4.5 amperes, then the capacity will go to 110 ampere-hours. The relationship between the capacity of a battery and the load current can be found in the manufacturer's literature.
Battery Life: The lifetime of any battery is difficult to predict, because it is dependent on a number of factors such as charge and discharge rate, depth of discharge, number of cycles and operating temperature extremes. It would be unusual for a leadacid battery to last longer than fifteen years in a PV system but many last for five to eight years.
Maintenance: Batteries require periodic maintenance. Even the sealed battery should be checked to make sure connections are tight and there is no indication of overcharging. For flooded batteries, the electrolyte level should be maintained well above the plates and the voltage and specific gravity of the cells should be checked for consistent values. Wide variations between readings may indicate cell problems. The specific gravity of the cells should be checked with a hydrometer particularly before the onset of winter. In cold environments, the electrolyte in lead-acid batteries may freeze. The freezing temperature is a function of a battery state of charge. When a battery is completely discharged, the electrolyte becomes water and the battery may freeze.

4. Determine The Sun Hours Available Per Day

Several factors influence how much sun power your modules will be exposed to:

When you will be using your system - summer, winter, or year-round.
Typical local weather conditions.
Fixed mountings vs. trackers.
Location and angle of PV array.

We have provided the following charts which show ratings that reflect the number of hours of full sunlight available to generate electricity. Your solar array's power generation capacity is dependent on the angle of the rays as they hit the modules. Peak power occurs when the rays are at right angles or perpendicular to the modules. As the rays deviate from perpendicular, more and more of the energy is reflected rather than absorbed by the modules. Depending on your application, sun tracking mounts can be used to enhance your power output by automatically positioning your array.

The charts reflect the difference in sunlight during spring, summer, autumn and winter. It is more difficult to produce energy during the winter because of shorter days, increased cloudiness and the sun's lower position in the sky. The charts list the sun hour ratings for several cities in North America for summer, winter and year round average. If you use your system primarily in the summer, use the summer value; if you are using your system year-round, especially for a critical application, use the winter value. If you are using the system most of the year (spring, summer and fall) or the application is not critical, use the average value. With the chart and the map, you should be able to determine a reasonable estimate of the sun's availability in your area.

5. Size Your Array

A2E will help you with this process.