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AC-coupled vs. DC-coupled solar

May. 06, 2024

AC-coupled vs. DC-coupled solar

Renewable Energy Trends to Watch in Solar – Part 1

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Humanity has significantly advanced from ancient Greek homes using passive solar heating to the Romans warming their bathhouse water with sunlight. The relentless pursuit of new customer needs, groundbreaking products, and innovative inventions allows us to harness energy from the world's most potent energy source. As this year gets underway, let’s explore some thrilling renewable energy trends in 2023.

The Rise of the Prosumer and Energy Management

“Prosumers,” a term introduced by Alvin Toffler in his 1980 book "The Third Wave," refers to consumers who actively participate in the production process. Homeowners and business owners with PV installations are active prosumers, producing some or all of their electricity and even selling it back to the grid. With the increasing popularity of PV as a renewable energy source and rising electricity costs, this growing group of prosumers requires additional tools to maximize their options. As PV adoption expands, optimizing its use becomes crucial. Prosumers face daily, hourly, or even minute-by-minute decisions: should I store my PV for later or use it now? When is it most efficient to run appliances like the washer/dryer—or for a factory owner, how can I best utilize on-site solar production for the manufacturing line? Should I charge my electric car with solar power, and if so, when? Enter energy management. PV systems aim to offer financial benefits as well as sustainable alternatives. However, system owners have other pressing matters than continuously programming and monitoring their home energy. Operational decisions should be made automatically with minimal attention required from the PV system owner to optimally take advantage of their PV production. Fortunately, SolarEdge has integrated smart energy management into SolarEdge Home, the SolarEdge residential solution. As a part of their smart energy ecosystem, deploying smart energy management is simple. Homeowners can manage essential loads through load controllers, select their preferences, while the SolarEdge Home Operating System orchestrates the home's energy automatically. The mySolarEdge app allows homeowners to monitor performance and make changes if necessary. SolarEdge makes being a prosumer particularly lucrative for users.

Community and Multi-dwelling PV Installations

Community solar is a growing renewable energy trend. The U.S. Department of Energy defines community solar as “any solar project or purchasing program, within a geographic area, in which the benefits of a solar project flow to multiple customers such as individuals, businesses, nonprofits, and other groups.” These projects provide solar energy access to those who might not otherwise be able to install it themselves. Such installations accelerate solar energy adoption and decarbonization while democratizing the process, making solar energy accessible to everyone. Some notable community solar stories include:

Puerto Rico

Puerto Rico's ambitious community solar project stands out for its significant quality-of-life improvement. Puerto Ricans have faced deadly hurricanes that frequently disrupt their electricity. Even under ideal conditions, their power grid is often marred by outages. Many residents have turned to solar solutions, and now, 7,000 installations will connect to form the US territory’s first virtual solar power plant (VPP). This move aims to reduce reliance on fossil-fuel-operated “peaker” plants and enable more island residents to benefit from solar.

Africa

Many areas in Africa lacked access to energy before the advent of solar solutions. Initiatives led by organizations like the World Bank and SNV Not for Profit have created mini-grids in previously unserved areas. To date, over 32 million Africans have access to basic electricity through such projects. However, with over 600 million still waiting for access, there’s much work to be done.

Global Efforts

Community solar also extends beyond underserved regions. The US boasts 1600 community solar projects across 41 states plus D.C., producing 5.3 gigawatts as of Q3 2022. Europe hosts an estimated 10,000 community solar projects, with Germany alone housing 900 energy co-ops. This trend is burgeoning, with solutions for individual multi-resident dwellings becoming mainstream.

SolarEdge Community Solar

A recent SolarEdge community solar site, the Hartford Pike Project in Foster, Rhode Island, led by Sunlight General Capital, exemplifies the potential. Despite challenges like shaded, undulating ground, SolarEdge technology enabled maximum energy production and precise module-level monitoring. Within its first nine months, the project generated 5.81 GWh of solar energy, of which 3.35 GWh was allocated to local residents and businesses.

Hybrid Hydro and Solar

Combining hydro and solar energy may be an ideal match. Both technologies reduce dependency on fossil fuels. However, each has inherent drawbacks. A European Joint Research Center study estimates that covering just 1% of Africa's hydroelectric reservoirs with solar panels could double capacity to 58 gigawatts and increase generating capacity by up to a quarter. Hydroelectric plants are crucial to the power grid, but droughts and evaporation threaten their viability. Solar can mitigate evaporation issues, as demonstrated by a University of California Merced study. Covering a 4,000-mile water canal with solar panels could save 65 billion gallons of water annually. Floating solar panels are easy to install and connected to the grid makes them more stable. Solar compensates for hydropower during dry periods, and floating PV provides higher energy yields due to cooler water surfaces. More renewable energy trends to come… In future updates, we’ll discuss trends like new EV applications, global job opportunities, solar panel end-of-life use, and other PV collaborations. Stay tuned!

DC coupling vs AC coupling

Solar power is more popular than ever. Integrating an energy storage system into your solar setup can save money, reduce your carbon footprint, and enhance energy reliability. Both AC-coupled and DC-coupled systems offer unique benefits, but what's the difference between them?

Let's explore the differences between AC- and DC-coupled solar systems, their benefits, and which one might be best for your property.

What is AC coupling?

In an AC-coupled solar system, DC power from solar panels is converted to AC by an inverter to power appliances. For battery storage, AC power must be converted back to DC and then back to AC when discharged, either for use or to feed the main grid.

What is DC coupling?

In a DC-coupled system, DC power from solar panels directly charges the batteries without intermediary conversion. To power appliances or feed the grid, electricity is converted to AC by an inverter, including any discharged battery power.

The 4 main solar battery system types

1. AC-coupled battery systems (grid-tied)

Increasingly popular for grid-connected properties, these systems facilitate the addition of energy storage capacity quickly and cost-effectively, whether from scratch or to an existing solar setup.

2. DC-coupled hybrid systems (grid-tied)

These highly efficient systems are excellent for charging batteries and using battery power, making them a popular choice for many homeowners and businesses.

3. DC-coupled systems (off-grid)

Best suited for small-scale operations such as homes, motorhomes, and boats, these systems efficiently charge batteries and power DC appliances.

4. AC-coupled systems (off-grid)

These systems are ideal for large-scale off-grid solar setups and are efficient when powering high AC loads during the day. An AC-coupled off-grid system can complement a grid-tied AC-coupled system. Hoymiles AC-coupled solutions allow connecting your system directly to a diesel generator, ensuring PV modules run even if the main grid shuts down.

How do AC coupling and DC coupling systems work?

Solar panels in a photovoltaic (PV) array generate DC electricity, essential for charging batteries and powering DC appliances. However, household and industrial appliances, as well as the main grid, require AC power. Therefore, an inverter converts DC to AC for usage or grid feeding.

Batteries need DC power for charging and provide DC power when discharging. Thus, an inverter is also necessary for charging batteries with AC power and using discharging battery power.

Both AC-coupled and DC-coupled systems convert electricity between AC and DC as needed, with key differences in setup and equipment.

Here’s a basic overview of how each system operates:

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How does AC coupling work?

In an AC-coupled system, DC power from solar panels is converted to AC by an inverter for appliance use or grid feeding. To charge batteries, AC power is reconverted to DC and converted back to AC for usage, requiring three conversions and two inverters.

How does DC coupling work?

In a DC-coupled system, DC power from solar panels charges the batteries directly via a charge controller, requiring only one conversion to AC for appliances or grid feeding. This makes DC-coupled systems simpler and generally more efficient.

What’s the difference between AC and DC coupling systems?

A primary difference in DC-coupled vs. AC-coupled systems is the number of inverters. AC-coupled systems require two inverters, while DC-coupled systems need only one. DC-coupled systems also use a charge controller to prevent battery overcharging.

Both systems offer different benefits and drawbacks, making them suitable for various situations. The choice often hinges on pricing, existing solar equipment, and efficiency priorities.

Below are some primary advantages of each setup to help you decide which is best for you.

Advantages of an AC-coupled system

Easier installation

AC-coupled systems are usually simpler to install, saving time and reducing overall costs.

Simpler upgrading

These systems are ideal for upgrading existing solar setups with energy storage, requiring only the addition of some equipment like a hybrid inverter without redesigning or rebuilding the main PV system.

Advantages of a DC-coupled system

Efficiency (when using energy storage)

DC-coupled systems are significantly more efficient when using battery power, requiring only one conversion from DC to AC, compared to three in an AC-coupled system, saving considerable energy.

Direct battery charging

In a power outage, DC-coupled systems can keep batteries charged directly from solar panels, maintaining functionality until grid power returns.

Full power utilization

DC-coupled systems effectively utilize the full capacity of solar panels, directing excess power to batteries and potentially improving cost-effectiveness by allowing for a higher DC:AC ratio.

Which solar plus storage system is best for your property?

Both AC- and DC-coupled solar systems offer excellent options, but several factors should be considered. If you already have solar panels and want to add energy storage, an AC-coupled system is often cheaper and quicker to install.

If installing a new solar system with energy storage, a DC-coupled system may provide better efficiency, potentially offsetting higher initial costs over the system's lifetime.