Solar 101

Will It Work for Me?

Modules

This is the key component of any solar photovoltaic system, which takes the sun’s energy and converts it into electrical current. Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect. Thin layers of semi-conducting material that is charged differently between the top and bottom layers are used to produce electricity. The semi-conducting material can be encased between a sheet of glass and or a polymer resin.There are three main types of solar panels (as well as the hybrid version) currently in commercial production, all of which are based on silicon semiconductors.

1. Monocrystalline Silicon PV Panels

Generally, mono-crystalline silicon solar PV is the best technology to deliver efficiency, as measured by wattage output related to the panel’s size. These are made using cells sliced from a single cylindrical crystal of silicon, typically converting around 15-24% of the sun’s energy into electricity.

2. Polycrystalline Silicon PV Panels

Also sometimes known as multi-crystalline cells, this type of solar cell is also made from thin wafers of silicon cut from artificially grown crystals, but instead of single crystals, these cells are made from multiple interlocking silicon crystals grown together. They are generally cheaper to produce than mono-crystalline cells, due to the simpler manufacturing process, but they tend to be slightly less efficient, with efficiencies of around 13-18%.

3. Thin-film PV PanelsRead More

The technology with the lowest market share is thin-film. It is a good option for projects with lesser power requirements with needs for light weight and portability. Typical thin-film solar cells are one of four types depending on the material used: amorphous silicon (a-Si) and Thin-Film Silicon (TF-Si); Cadmium Telluride (CdTe); Copper Indium Gallium Diselenide (CIS or CIGS); and Dye-sensitized Solar Cell (DSC) plus other organic materials. As amorphous silicon absorbs light more effectively than crystalline silicon, the cells can be thinner – hence its alternative name of ‘thin film’ PV. Amorphous silicon can be deposited on a wide range of substrates, both rigid and flexible, which makes it ideal for curved surfaces or bonding directly onto roofing materials.

Invertors vs. Micro-Inverters

We believe that inverters are an important part of any solar installation; they act like the brain of the system. The solar panels generate direct current (DC) electricity. As DC electricity cannot be used directly by common household appliances nor fed into the main grid, it first needs to be converted to Alternating Current (AC). Although the inverter’s main job is to convert DC power produced by the solar array into usable AC power, it has other roles as well. For instance, inverters enable monitoring so installers and owners can see how a system is performing.

There are two major types of inverter that can be installed for your solar photovoltaic system:

1. String Inverters (also known as Central Inverters)

These are used in grid tied systems where the solar panels are wired together in series, which is known as a string of panels. Each string of panels is connected to a string inverter, which converts the DC current to AC for use in the home and selling back to the grid. You can imagine each string as a mini power station, producing electricity. String inverters can also be paired with power optimizers, an option which is gaining popularity. Power optimizers are module-level power electronics meaning they are installed at the module level, so each solar panel has one. Some panel manufacturers integrate their products with power optimizers and sell them as one solution known as a Smart Module.

2. Micro-Inverters

Micro-inverters are also becoming a popular choice for residential and commercial installations. Like power optimizers, micro-inverters are module-level electronics so one is installed underneath each panel. However, unlike power optimizers which do no conversion, micro-inverters convert DC power to AC right at the panel and so they don’t require a string inverter. Also, because of the panel-level conversion, if one or more panels are shaded or are performing on a lower level than the others, the performance of the remaining panels won’t be jeopardized. Micro-inverters also monitor the performance of each individual panel, while string inverters show the performance of each string. This makes micro-inverters good for installations with shading issues or with panels on multiple arrays facing various directions. Systems with micro-inverters can be more efficient, but these often cost more than string inverters. Some panel manufacturers have already integrated micro-inverters into their panels, similar to Smart Modules but instead these are known as AC Modules.

Racking system

Since every facility is unique and contains various structural designs, there are various racking systems used to install a solar system in order to make it more suitable for both residential and commercial projects.

1. Roof Mount

There are a few things that need to be looked at if a roof mounted system is what you have in mind. The first and probably most important aspect that needs to be taken into consideration is, whether your roof will allow your panels to have the optimal sun exposure while also not being obstructed by shade from other nearby objects like buildings or trees. Most common/economical method of mounting solar panels is on the roof of your home or business. Any roof pitch or orientation from East to South to West can accommodate panels, as well as any roof type from asphalt shingles, concrete or Spanish tiles, and metal roofing.

2. Ground Mount

Ground mounted systems make panel orientation much easier because they can be built to face any direction to maximize sun exposure. Cooler temperatures are ideal for solar panel use; because the lower the temperature the higher the efficiency of the panels. If you have the space for a ground mounted setup, because of better air flow under the panels in comparison to their roof counter parts, there will be a slight performance increase. However, it does take more materials to build a ground system because it needs a place to be mounted and the wiring needs to be trenched to connect the panel(s) to the facility. There are two basic types of ground mounted solar panel systems:

Standard Ground Mounts use metal framing driven into the ground to hold your solar panels up at a fixed angle. Some standard ground mounted solar panel systems can be manually adjusted a few times a year to account for seasonal shifts of the sun.
Pole Mounts support multiple solar panels on a single pole and elevate panels higher off the ground than a standard ground mount. Pole mounts often incorporate tracking systems, which automatically tilt the solar panels to capture the optimal amount of sunshine.

Monitoring system

The first place most system owners look to assess their grid-tied PV system’s performance is their electricity bill. But examining bills won’t give you the big picture. Since most utility companies offer net metering, you’ll only be provided with the information they measure: How much electricity you import from the grid and, depending on the utility meter, how much your system exports to the grid. Because your bill won’t typically show how much PV-generated energy the home consumed, you won’t be able to determine how much energy your PV system produced overall by using the bill as your only guide. One of the most enjoyable aspects of having a solar PV system is tracking how much energy the system has generated over time. There are many PV monitoring options available in the market, but in all of the cases the energy monitoring system has to be compatible with the inverter.

In most cases, the generated energy can be monitored in 3 ways:

Direct PC Connection: The inverter can connect to a PC via a CAT5 cable or a Bluetooth device. The free monitoring software is downloadable from the inverter manufacturer’s website. This is the cheapest method of monitoring available. It gives the user the advantage of data logging.
Monitoring Display Unit: The information from one or multiple inverters are combined and displayed in the display unit. The information is gathered through a CAT5 cable or Bluetooth units. Such systems are also known as wireless energy monitoring systems. The dedicated display item is an additional cost but it gives the system owner the option of monitoring the system through a display.
Internet Based Monitoring: The energy output data is transferred to a router, thus making it available on the internet. Every user has a dedicated password protected website. The main advantage of internet based monitoring is that the information is readily available and logged at a remote location. The router and the card that plugs into the inverter are the additional costs of this system. This type of third party monitoring may be required for production based incentives.

(NEM) net energy metering?

1. Net Energy Metering

Net energy metering, or “NEM”, is a particular billing arrangement that provides credit to customers who own a solar PV system for the full retail value of the electricity their system generates. Under NEM, the customer’s electric meter monitors how much electricity is consumed by the customer, and how much excess electricity is generated by the system and sent back into the electric utility grid. Over months period, the customer has to pay only for the net amount of electricity used from the amount of electricity generated by their solar system (in addition to monthly customer transmission, distribution, and meter service charges they are subjected to).

2. How Net Energy Metering Works

At any time of the day, a customer’s solar system may produce more or less electricity than they need for their home or business. When the system’s production exceeds the customer demand, the excess energy generation automatically goes through the electric meter into the utility grid, running the meter backwards to credit the customer’s account. At other times of the day, the customer’s electric demand may be higher than the renewable energy system is producing, and the customer relies on additional power needs from the utility. Switching between solar system’s power and the utility grid power is instantaneous- therefore customers never notice any interruption in the flow of power.

3. Benefits of NEM

NEM is a key factor and a doorway to optimizing the rate of return on your solar investment.

Allows customers to zero-out their bills.
Credits customer accounts at full retail rates.
Accurately captures energy generated and consumed, providing customers with annual performance data.
Allows clients to even receive money if their system productions surpass a client’s yearly energy consumption.