What Are Solar Power Requirements?

Solar power refers to the conversion of energy from sunlight into electricity. It is a renewable energy source that relies on the sun’s rays striking photovoltaic panels, known as solar panels or PV panels, to generate electrical power [1].

While solar power has been used in a limited capacity for decades, it has grown significantly in recent years due to technological improvements, cost reductions, and government incentives [2]. The first modern silicon PV cell was created in 1954. However, solar power did not become widespread until the late 1990s and 2000s, when technology improved efficiency and costs declined. As of 2020, solar contributed nearly 3% of total electricity generation worldwide [1].

Solar panels work by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity. Panels can be used individually or linked together into PV systems that are mounted on rooftops or ground-based solar arrays. The direct current (DC) electricity generated is then converted by an inverter into usable alternating current (AC) electricity that can power homes, businesses or even feed into the electricity grid [1].

[1] https://en.wikipedia.org/wiki/Growth_of_photovoltaics

[2] https://www.statista.com/statistics/217177/global-projected-growth-of-solar-power-by-2020/

Table of Contents

Solar Irradiation Requirements

The amount of solar irradiation, also known as insolation, is a key factor in determining the viability of solar power systems. Areas that receive more annual sunlight are better suited for solar power. According to research, baseline solar irradiation requirements for concentrating solar thermal systems are around 2,000 kWh/m2/year (Ahmad, 2017).

The southwestern United States, especially California, Arizona, New Mexico, and Nevada, have some of the highest levels of solar irradiation in the country. This region receives 2,500 to 3,500 kWh/m2/year or more, making it an ideal location for large-scale solar power installations (EPRI, 2007). Parts of the Southeast and Texas also have suitable solar resources.

The National Renewable Energy Laboratory (NREL) provides detailed solar insolation maps that show the average daily solar radiation by region. These maps help determine the viability of solar power by location. In general, solar power systems require at least 5 sun-hours per day, or 1,825 kWh/m2/year, to be cost-effective.

Photovoltaic System Components

The main components of a photovoltaic solar system include:

Solar Panels

Solar panels, also known as photovoltaic (PV) modules, are used to convert sunlight into electricity. They are made up of solar cells that absorb photons from sunlight and convert them into an electric current. Solar panels come in different technologies, sizes and efficiencies. Some key factors to consider when selecting solar panels are the power output, physical size and durability. Most residential solar systems use monocrystalline or polycrystalline silicon panels [1].

Inverters

Inverters convert the DC power output from the solar panels into AC power that can be used or fed back into the electricity grid. There are string inverters that connect to solar panel strings and microinverters installed on each panel. Inverters are rated by their maximum AC output power. Grid-tied systems require inverters that synchronize the frequency and voltage with the utility grid [2].

Batteries

In off-grid solar systems, batteries store energy produced by the solar panels for use when the sun is not shining. Common battery technologies used are lead-acid, lithium-ion, and saltwater batteries. Key factors when selecting batteries include capacity, depth of discharge, cycle life, and operating temperature.

Charge Controllers

Charge controllers regulate the voltage and current from solar panels to prevent overcharging and prolong battery life. They ensure the batteries are charged efficiently and safely.

Sizing a Solar System

Properly sizing a solar system is crucial to ensure it can meet your energy needs efficiently and cost-effectively. The key steps are to:

Calculate your household’s average daily energy consumption. Review past electric bills to estimate kWh usage per day. Factoring in future energy needs from electric vehicles, appliances, etc. is also important.

Determine the solar resource available. Use your location’s average daily peak sun hours, which measures solar irradiance. 4-6 peak sun hours per day is typical.

Size the solar array accordingly. Use the energy usage and sun hour data to calculate the system size in kW. Allow for at least 20% more capacity than current needs.

Choose compatible system components. Select PV panels, inverters, batteries if off-grid, and other equipment matched to your array size.

Right-sizing a solar system takes careful planning and calculations. Oversizing can add unnecessary costs, while undersizing leads to unmet energy demand. Professional installers can provide sizing assistance for best results. As per The Ultimate Solar Power Design Guide, the sizing process links energy needs, budget, and location.

Mounting and Orientation

Properly orienting and tilting solar panels is one of the most important factors in maximizing their energy production. For rooftop systems in the northern hemisphere, solar panels should face true south and be tilted at an angle equal to the latitude of the location plus 15 degrees in winter or minus 15 degrees in summer. Facing solar panels true south optimizes energy production throughout the year as the sun’s path across the sky shifts [1].

Solar panels can also be mounted on the ground using racking systems. Ground-mount systems allow panels to be tilted for optimal orientation and can avoid shading issues caused by trees or buildings. Tracker systems that move throughout the day to follow the sun’s path across the sky can increase energy production by 20-30%, but have higher costs and maintenance requirements [2]. Properly orienting fixed rooftop or ground-mount systems is the most cost-effective way to maximize solar panel output.

Permits and Regulations

Installing solar panels on your home usually requires obtaining permits from your local jurisdiction. Permits are required to ensure the solar system meets all safety and electrical codes. The permitting process varies by location, but generally involves submitting an application, plans, and other documentation, paying permit fees, and scheduling inspections.

To obtain permits for solar panels, research the specific requirements for your city or county. Many local governments provide permitting guides for residential solar installations on their websites. You’ll need to submit an application form, site plan, and electrical diagram. Permit fees are typically a few hundred dollars. Solar permits often require separate structural, electrical, and building inspections from the local building department.

In addition to city or county permits, your homeowners association (HOA) may require approval prior to installing solar panels, especially for common aesthetic concerns. Check your HOA covenants before moving forward. Some states prohibit HOAs from restricting solar installations. You should be prepared to show your solar plans follow safety codes and manufacturer guidelines.

It’s important to have all required permits and inspections for any home solar project. Starting solar installations without proper permits can lead to fines, removal of equipment, or other penalties. Consulting with local jurisdictions and inspectors early in the process ensures your solar system meets all codes and regulations.

Grid-tied vs Off-Grid

Solar electric systems come in two main configurations – grid-tied and off-grid.

In a grid-tied system, the solar panels are connected to the local utility grid. The solar energy that is generated first supplies the home’s electricity needs. Any excess electricity is then fed back into the grid in a process called net metering. This allows households to get credit for the extra solar power they produce. Grid-tied systems do not require battery storage since the grid essentially acts as the battery. They are generally less expensive than off-grid systems.

According to Paradise Solar Energy, some key benefits of grid-tied solar include:

No batteries needed

Lower upfront costs
Can size system based on average usage, not peak demand
Excess power fed back to grid for credit or payment

Off-grid systems operate independently from the utility grid. All of the electricity is generated from the solar panels and stored in batteries for use when the sun isn’t shining. Off-grid systems require energy storage and often diesel generators for backup power. They are more complex to size and install. However, they provide energy independence and reliability.

According to Growatt, key aspects of off-grid solar include:

Freedom from the utility grid

Requires battery storage
More expensive upfront costs
Sized for peak energy demand

Provides backup power during outages

Maintenance

Proper maintenance is key to ensuring a solar panel system continues operating efficiently for its full lifespan of 25-30 years (Energysage, 2022). There are some basic maintenance tasks that solar panel system owners should regularly perform.

Cleaning solar panels is one of the most important maintenance tasks. Solar panels can lose up to 25% of their efficiency from dirt and dust buildup over time (Conserve Energy Future, 2022). It’s recommended to clean panels every 2-4 times per year, depending on environmental factors. Soft brushes, microfiber cloths, and mild detergent can be used to gently clean the panels.

Checking electrical connections is also advised every 6 months. Tightening any loose wire connections helps prevent issues down the line. Thermal imaging can identify hot spots that may indicate a faulty connection.

The inverter is the device that converts DC electricity from the solar panels to AC electricity for use in the home. Inverters typically last 10-15 years before needing replacement (Medium, 2022). Monitoring inverter performance and being prepared for replacement costs is prudent.

Costs and Incentives

Going solar can involve significant upfront costs, but there are many incentives available to help reduce system costs. The average cost for a residential solar panel system in the U.S. is around $2.80 per watt [1], so a typical 5-kilowatt system would cost around $14,000 before incentives. However, the return on investment is attractive thanks to energy bill savings and incentives.

One major incentive is the federal solar Investment Tax Credit (ITC), which offers a 26% tax credit for systems installed in 2022. This tax credit applies to both residential and commercial systems [2]. Many states and utilities also offer additional incentives like rebates and net metering programs that compensate solar customers for excess power sent back to the grid.

The combination of incentives and bill savings provides a payback period of around 6-8 years for a residential solar system. The system will then provide nearly free electricity for the remainder of its 25+ year lifespan [3]. Going solar is a significant investment, but the long-term savings make it financially worthwhile for many homeowners.

Choosing an Installer

Picking the right solar installer is crucial to ensure your system is designed, installed, and maintained properly. When researching contractors, there are several key factors to consider:

Get quotes from at least 3 installation companies. Compare bid prices, experience levels, equipment brands, warranties, maintenance services, and customer reviews. Be wary of quotes that seem too good to be true. According to Picking A Solar Installer: A Homeowner’s Guide, the national average cost for a 6 kW solar system is around $18,000 before incentives.

Look for established local and national companies with demonstrated experience installing systems similar to yours. Ask how long they have been in business and how many installations they have completed. According to What To Look For When Choosing A Solar Installer, newer companies may lack the expertise and stability of more seasoned installers.

Verify relevant licenses, insurance, and certifications like NABCEP. Make sure installers will pull all required building permits and comply with local regulations. According to How to Choose The Right Solar Company, unlicensed contractors often cut corners or use subpar equipment.

Carefully inspect warranties on labor and equipment. Many panels come with 25 year power production guarantees. Opt for the longest labor coverage you can get. According to How to Choose The Right Solar Company, multi-year warranties protect against defects and give you recourse if issues arise.