Understanding the Key Components of a Residential Solar Electric System
There are five primary components to any residential solar electric system. This design approach makes for easy installation and maintenance.
- Solar panels– also known as photovoltaic or PV panels, they convert solar energy into DC electricity.
- Inverters – convert the Direct Current (DC) electricity into usable Alternating Current (AC) electricity to power your home & appliances.
- Mounting systems - also called racking systems, they secure your solar panel array to your roof or ground mount.
- Smart Monitoring systems – allow you to track the output and monitor the performance of your solar panels and inverters in real time from your smartphone or computer. A solar monitor is installed at the same time your solar panels are installed.
- Solar battery storage - holds the excess power generated by a solar system. Once
installed, the battery allows the homeowner to gather and store solar energy. The energy in the
battery can be used at night or in a grid outage.
- Most Texas homeowners say that their primary reason for installing solar storage is to cut their dependency on the power grid. When the ERCOT electrical grid goes down for any reason - a major storm, hurricane, or rolling blackouts - a solar storage system will keep your lights on.
- Warranties - while not a part of the system, warranties help assure you that your service and support needs will be covered if a solar equipment problem ever occurs. As part of the buying process, it is crucial to evaluate and compare the product warranty coverage of panel manufacturers.
Solar Panels - A Bullet Point Overview
Our sun is an inexhaustible source of power for our planet. Advances in technology and solar panel design make harnessing the sun’s power the right choice for an increasing number of Texas households every year.
What Is A Solar Panel?
Solar panels collect energy in the form of sunlight and transform it into usable electricity. Solar panels consist of silicon solar cells and circuitry covered by glass and finally surrounded by a metal frame. Exact dimensions of solar panels will vary by manufacturer, but are generally 3.5 ft wide by 6 ft in length.
How Solar Panels Provide Residential Power
- In daylight hours, the solar cells in your solar panels absorb the energy from photons (sunlight);
- That solar panel energy is transformed into direct current (DC) electricity within the panel;
- DC electricity travels through an “inverter” which converts DC into alternating current (AC) electricity - the type of electricity you use in your home every day.
- Once converted to AC, you can use the electricity to power your home, charge your electric vehicle, charge your solar battery, and send power back to be stored on the grid.
Choosing The Best Solar Panel For You
There are several points to consider while researching the solar panels that best fit your home and budget. Chief among them are panel quality, structural durability, and long-term energy production. If you would like to know more about choosing the best panel for your home, click on Solar Home Review.
Inverters - And Their Evolution
Solar panels collect the energy from sunlight and convert it into direct current (DC) electricity. Inverters convert that DC electricity into user-friendly AC electricity.
Solar inverters can be divided into two categories: Centralized (or string) inverters and micro-inverters. String inverters can also add power optimizers to function similarly to a micro-inverter system.
Centralized (or String) Inverter
In this type of system, one primary inverter connects to and converts the entire array's DC electricity production into usable AC electricity. Once converted to AC, the electricity flows into your main breaker box.
String inverters are frequently the least expensive inverter option. Earlier generations of string inverters have been the most commonly installed inverter type. There is, however, a major drawback: when electricity production from any single panel (of many) in the string decreases (as may happen due to shading), the entire array’s performance drops to the level of that least producing panel. This is the reason most users of Solar Home Review do not opt to use a string inverter configuration.
Power optimizers
A power optimizer is a hybrid inverter combining micro-inverter and string inverter systems. Similar in arrangement to micro-inverter systems, power optimizers are installed at each panel. The conversion of DC electricity to AC electricity, however, does not occur in the panel. Instead, optimizers “condition” the DC current before sending it to a large central inverter to be transformed into usable AC electricity.
Similar to micro-inverter systems, power optimizers will perform when one or more panels of an array are shaded or when arrays have panels facing various directions. Solar systems using power optimizers will generally cost a little less than micro inverter systems, but more than string inverter systems.
Micro-inverters
Micro-inverters, as the name implies, are small inverters installed on each solar panel. This configuration allows each panel to operate independently at maximum production even when some of its sister panels are shaded, This configuration also works well when a solar array has panels facing various directions. Micro-inverters maximize performance and electrical output of the entire system. Micro-inverter systems initially cost more than string inverter systems, however, that cost will be more than recovered when factoring in the value of increased electricity production.
Monitoring your System’s Performance: Smart Solar Monitoring Systems
A Smart Solar Monitoring System maintains detailed information of the performance of your home solar energy system. It monitors and creates easy-to-read reports on the productivity of your solar arrays on an hourly basis.
The monitoring system available to you depends on which inverter you choose. Solar Home Review recommends only using inverters from the industry’s top manufacturers. A glance at your phone or laptop will show you your home's electricity consumption, solar energy production, level of battery storage, and more. A great monitoring app will keep you on top of the total savings of your solar electric system, as well as promptly identifying any potential issues. It will also ensure maximal solar electric production – and financial returns!
Racking and Mounting
Solar racking and mounting hardware attach your solar panels to your home's roof or the ground.
For maximum electricity production, solar panels should be mounted facing South at angles between 30 and 45 degrees, depending on latitude. Panels facing East and West will also work well, using a pitch of five degrees or more. An East or West alignment will result in a slight reduction in electricity production potential. Expect a 10 to 20 percent reduction in electricity compared to panels installed under ideal south-facing alignment.
Most residential roof-mounted solar systems are “lie-flat” systems. This simply means the racking and solar panels are installed parallel to the pitch of your home’s roof.
In some applications, a solar array may also be affixed to racking mounted on the ground. This is called a ‘ground mounted system’. The benefit of a ground mounted system is that the array can be positioned in a desirable location with both perfect direction and pitch to generate optimal production from a panel array.
Solar Battery Storage What You Need To Know
Texas weather can be extreme. Freezes and floods, heatwaves and hurricanes are compounded by our swelling population to put a heavy toll on our ERCOT grid. Nationwide grid failures, brownouts, and blackouts are becoming regular occurrences.
In the seven years from 2013 to 2020, the outage time that grid failures lasted doubled in duration.
| Year | Incidents of Power Outage | Customers Affected |
|---|---|---|
| 2013 | 174 | 8.8 million |
| 2014 | 214 | 16.8 million |
| 2015 | 143 | 7.3 million |
| 2016 | 141 | 8.5 million |
| 2017 | 150 | 16.6 million |
| 2018 | 211 | 16.9 million |
| 2019 | 278 | 10.6 million |
| 2020 | 383 | 25.5 million |
On Feb. 11, 2021, winter storm Uri plunged Texas and the entire Gulf Coast into a full-scale energy crisis
The Storm demanded action that was beyond ERCOT’s planned response. The National Weather Service reported freezing rain and drizzle across North and Central. Texas as the storm began rolling in that morning. Accumulations of up to one-half inch of ice were reported. The grid failed. Sadly, the Texas Department of State Health Services (DSHS) reported that 246 Texans lost their lives during that bitter cold.
Having a backup solar battery system is the difference between grid dependence and grid independence, and in extreme situations it can be the difference between life and death. Solar battery storage also allows solar consumers to elect to use power from their battery during peak usage hours when grid supplied electric rates are highest – thereby easing the strain on the grid.
Types of Solar Batteries
The chemistry used in solar batteries may differ from one manufacturer to another. Additionally, a particular battery type may be better suited for a specific application than a battery with a different chemistry. Most of the common battery types available in 2023 fall into one of two broad categories:
Lead-acid Batteries or Lithium-ion Batteries
Aside from batteries being constructed of chemically dissimilar materials, perhaps the most fundamental distinctions may be performance and price point. Generally, Lead-acid batteries tend to be more economical, whereas lithium-ion based batteries are more efficient and have a higher price point.
Deep cycle Lead-acid batteries are not normally a first choice in residential grid tied systems. They are, however, much more common in complete off grid systems. These batteries are engineered to be larger and heavier than lithium batteries in order to withstand routine drainage of the charge. Lead-acid batteries require more time to recharge after discharge. Lead-acid batteries also have a shorter lifespan compared to the lifespan of lithium-based batteries, They also require routine maintenance.
Lithium Batteries
A more popular option among Texas residential solar consumers is quick charging, longer lasting Lithium based battery variations. These batteries are smaller and lighter compared to lead-acid batteries.
Of these Lithium based variations, Lithium Nickel Manganese Cobalt Oxide (NMC) is the most common, as this technology has been used in residential solar for many years. NMC technology has been real world tested over many years. Compared to other lithium-based batteries, NMC can be a very economical battery option. The cobalt in NMC batteries reduces the likelihood of thermal runaway/fire. The Tesla Powerwall is a well-known Lithium Nickel Manganese Cobalt Oxide battery.
What is Thermal Runaway?
The term thermal runaway describes an exceedingly rare uncontrolled thermal reaction that can take place in solar batteries. It is a chain reaction within a battery cell that occurs when the temperature inside a battery reaches the point that causes a chemical reaction to occur. It can then spread to other batteries and can be very difficult to stop once it has started. Residential solar batteries, however, are required to undergo the rigors of strenuous testing to ensure it never happens. Further preventative measures include component arrangement, protective outer casings around the battery cells, and enhanced internal cooling to further diminish the already miniscule risk of an uncontrolled thermal reaction.
Lithium Iron Phosphate (LFP)
Lithium Iron Phosphate or LFP batteries rely on a more recently developed chemical formulation, allowing for more efficient energy retention. LFP batteries generally have a higher power rating and lower energy density rating. However, this new phosphate chemistry comes at a higher price point.
Iron (Fe) in LFP batteries has resulted in reduced heat output. That effectively means most LFP batteries do not require the robust ventilation and/or cooling (if any) of NMC batteries.
Cooler operating temperatures make LFP batteries a great option for wider possibilities in mounting locations - including indoors.
Batteries with LFP chemistry provide longer life of service over other lithium-based batteries. Sonnen and Enphase are both batteries that use LFP chemistry.
Compare Your Solar Battery Options Today With Solar Home Review
If you are considering a residential solar battery for your home, start with speaking to a certified solar specialist. Solid professional advice from a specialist with electrical expertise and compete, understanding of the latest industry best practices can turn a complicated process into an enjoyable experience.
Solar Home Review will help you get the best information about residential solar storage options available. If you want to learn more about solar-plus-storage options near you, we are happy to help. Simply complete the quick questionnaire below and, we will provide specific answers to your questions about the solar products you’re interested in.
AC-Coupling vs DC-Coupling
The solar panels on your roof (or ground array) create direct current (DC) electricity that needs to be converted into alternating current (AC) electricity for use in the home. A system that is AC-coupled makes this DC to AC conversion at the inverter when charging a solar battery. It then reconverts it back to DC for storage. When the battery is discharged, the electricity is converted yet again back to AC. In contrast, in a DC-coupled system, the current conversion from DC to AC is only required to happen once.
AC-coupled batteries lose a bit of their efficiency during the conversion and reconversion process. In addition to higher efficiency ratings, DC-coupled batteries are able to recharge from solar panels - even when the grid is down. DC-coupled systems may be worth considering if you are installing an entirely new system. However, DC coupled systems are more complex to install and may require additional costs. Conversely, AC-coupled systems are easier to install and easy to add on to pre-existing residential solar systems.
Battery Capacity
Battery capacity is a measurement of a solar battery's electrical storage, expressed in kilowatt-hours (kWh). The term “usable capacity” is also expressed in kilowatt-hours (kWh) and measures the amount of energy a battery has available for immediate use.
Battery function requires some energy, so the “usable capacity” of a battery is lower than the overall “battery capacity”
Proper pairing of the size of your battery’s capacity in relation to the amount of electricity produced by your solar system is an important. Most solar arrays will produce in excess of needed daytime electricity consumption, This allows you to store the unused electricity for later use. If your battery is undersized, you may be disappointed in the event of a grid failure. If your solar battery is too small, you may not be able to use some electric appliances. If your battery capacity far exceeds your storage needs, then it may be too big for your system, and you will not see any benefit. It will be an unnecessary added solar investment.
Depth of Discharge
Depth of discharge (DoD) is a ratio expressed in percentage. It is the ration between a battery's full capacity and its usable capacity. Lead Acid batteries hover around 50% while lithium ion-based batteries range between 80% and 99+%. As fully discharging a battery may shorten its overall service life, many batteries are engineered with a limited DoD, so they discharge at a lower percentage of the battery’s full capacity.
Power Rating
“Power rating” is a measurement expressed in kilowatts (kW). It is the amount of electricity a battery can discharge over a given period. Power ratings are measured in continuous power and peak power.
- Continuous power: is how much electricity a battery can produce in a given time period. Continuous power is an important metric of consideration when determining how long your home can be powered by a specific battery.
- Peak power: as the name implies, peak power is a measurement of the maximum, instantly available power a battery can produce.
A low-capacity battery with a high peak power rating can deliver short bursts of electricity, but is unsuitable for power production for extended time periods. Alternatively, high-capacity batteries with low peak power ratings are able to provide electricity for less demanding devices for extended periods of time.
Round-trip Efficiency
Round-trip efficiency is a ratio, expressed in percentage, measuring the amount of available electricity after the loss experienced during the charging process. The higher a Round Trip Efficiency percentage, the higher amount of energy is retained after charging.
Can I go off-grid with solar + storage?
Generally speaking, going completely off-grid usually isn't the most economical option for most
residential solar applications. Going off-grid usually requires a larger solar panel array and
storage system. More often than not, when a homeowner says they want to go off-grid with solar
and storage, what they're actually seeking is an assurance that their electricity will stay up
during the next grid outage.
In either case, Solar Home Review has you covered.
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