Understand the pros and cons of software and communications decisions

software and communications strategy

At times, it is optimal to have connected devices in place. At other times, it creates another point of failure.

As is true in every industry today, solar installations are becoming smarter and more connected by leveraging the power of real-time data, remote controls and responsiveness to improve project and product performance. Project owners and financing partners cheer software platforms that enable sophisticated communications.

Without question, software and communications can play an important role in many storage projects. First and foremost, battery communication capabilities may be required or at least strongly recommended when integrating with certain inverters, chargers and other power electronics.

At the residential level, such software and communications allow for higher level monitoring capabilities that provide both the installer and homeowner with granular data on system performance and health. Software can also improve ease-of-programming.

When it comes to C&I projects, software and communications plays an even more important role. These large-scale projects often combine large numbers of interconnected technology assets and hardware that require communications and software to communicate with one another and perform as an integrated system.

But be careful…

That said, as important as these technologies are to the future of the renewable energy industry, be sure to proceed with caution.

At times, it is optimal to have connected devices in place. At other times, it creates another point of failure. When an installation’s on-site management is dependent on interconnectivity through networks and airwaves, what happens when those conduits cease to function?

In an environment in which renewable energy + storage deployments have become more and more critical in the face of escalating catastrophic events, it’s important to recognize that software and communications can create barriers to energy resilience when the grid and Internet networks are unavailable. The result is stranded assets that do not have the ability to turn back on without the intervention of a highly trained professional.

After Hurricane Maria in Puerto Rico, for example, homeowners did not have the ability to bring their systems back online, and expert software technicians were unavailable to service offline inverters and energy storage systems for some time. The same issue has posed problems in remote communities, where technical expertise to reset and restore system function has not been available locally. In this kind of situation it often makes sense to have a simpler, user-friendly battery system design.

Be sure to weigh the added cost and complexity of installing a smart storage system. With additional wiring and programming required, installation can be longer and more cumbersome without added benefit.

Unfortunately there is no one-size-fits-all solution when it comes to communications and software. In some cases, connectivity is essential to project success. But in other situations, building resiliency is better achieved through a simpler approach that empowers the end user to own, control, manage and fix their own systems. The key for installers is to understand both and be able to advise their customers as to which is most advantageous for their unique circumstance and project objects.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

— Solar Builder magazine

Design a battery bank to grow with your customers

modular battery storage design

Whether residential or commercial, energy needs and usage inevitably evolve over time — most often with power loads and required energy increasing as operations or families grow.
With that reality in mind, the ability to deliver energy storage solutions that can scale and expand in sync with an end customer’s needs is an important installation selling point.

Understanding scalability

Battery size and modularity can make a big difference when it comes to project scalability, optimization and ease of installation, but not every battery has the ability to scale. Some are limited to two-to-four in parallel configurations, while other batteries are designed to scale to any desired kWh.

For example, at the Taft Botanical Garden in Ojai, Calif., the property owners realized that their ground mount solar array was generating significantly more energy than anticipated — and more than their initial 21 kWh battery bank could store. At the same time, special events at the garden were taxing the system with high demand. The system installers were able to easily double the size of the battery bank by adding new batteries to the existing bank (blending old and new), harnessing more solar power to the benefit of the property’s operational needs and budget.

Consider kWh optimization and space utilization

Energy storage modularity is also a benefit when it comes to optimizing storage for each unique deployment case and environment. Smaller building blocks allow more flexibility to narrow in on the exact kWh capacity best suited to a project. Modular batteries also allow more freedom when it comes to space utilization, making it possible to install in small, crowded or uniquely configured locations.

At a home in England, for example, the homeowners had only one, tiny “Harry Potter-sized” under-stair closet available to house their battery bank. With small, modular batteries, that installation location proved to be no problem.

Simplify, accelerate your installs

Common battery weights range from 50 lbs to more than 400 lbs. Depending on how much your battery weighs, the installation process will be very different.

Larger batteries require heavy equipment to install and present limitations as to how they can be installed. For example, mounting a 400 lb battery on a wall would be impractical, whereas simple brackets and standard shelving can easily house smaller, lighter weight batteries. You may also find other limitations with larger battery building blocks such as doorway restrictions and stairwell limitations when installing.

When it comes to choosing the right battery for your next storage project, consider solutions that can scale and expand. The added flexibility and simplicity will be appreciated by customers both in the present and years down the road.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

— Solar Builder magazine

Demand charge management tips for the commercial, industrial segment

Simpliphi commercial solar storage installation

Storage solutions must be customized to align with the specific power or energy demands of a commercial or industrial customer.

It’s no secret that commercial energy users in every industry are seeking to reduce energy costs today and achieve long-term cost predictability for the future as utilities implement increasingly unfavorable rate structures. Energy storage provides a powerful, multifaceted solution to lock in rates and achieve power security.

Savings opportunities

Energy storage can provide a significant ROI when it comes to utility bill savings:

Demand charges: Demand charges are often calculated based on the highest 15-minute average electrical use recorded in one month which are then applied to all 12 months. As a result, demand charges make up a significant percentage of all commercial and industrial utility bills — typically between 30 and 70 percent. In the U.S., 25 percent of commercial customers (roughly five million businesses) pay demand charge rates of more than $15/kWh and these demand charges continue to rise. Energy storage enables commercial and industrial customers to discharge their batteries and use battery-stored energy rather than grid power to avoid peak demand spikes.

Time of use rates: Time of use rates are calculated at a specific time of day when the utility charges a premium rate to reduce high demand on the grid. Energy storage offsets utility rates by reducing grid power usage during peak hours and shifting usage from peak to non-peak hours.

Large-scale battery banks have both sufficient available power and energy storage to cover and “smooth out” consumption demands and protect utility customers from unfavorable rate structures.

How performance factors into the equation

Beyond initial utility savings, the performance profile of both the batteries and all-in-one solutions matters when it comes to maximizing the performance and economic return associated with a commercial energy storage system. As we’ve discussed in earlier posts, pay close attention to warrantied cycles (battery expected life), max charge/discharge or the battery’s available power, as well as usable capacity and efficiency.

Just as PV array size decisions are important for generating the optimal amount of power and ROI for a project, so too must storage solutions be customized to align with the specific power or energy demands of a commercial or industrial customer.

Consider how storage addresses peak demand charges.  These charges are based upon power consumption, so it is important to have a skilled professional build a profile of power demands exceeding the line in which the demand charge is met.

For instance, a professional might determine that the highest 15 minute interval rate that a warehouse uses is 100 kW. The installer can then reduce this rate with the strategic addition of solar and storage to help smooth out the load profile that the utility sees and thus reduce costly demand charges.

There are high voltage energy storage systems available that allow you to customize exactly the voltage, peak power, capacity and system size you need for every building, location and use-case in your portfolio. This approach can provide significant cost savings over out-of-the box solutions, requiring you to buy only the storage you need and allowing you to add on additional storage incrementally down the road.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

— Solar Builder magazine

Temperature considerations in battery selection

remote site simpliphi battery installation

As is true with solar projects, the range of environments in which energy storage is being applied has grown and diversified significantly. This diversification in deployments means a deeper understanding of the temperature-related performance and safety issues tied to battery selection and storage system design.

For solar installers, understanding which battery chemistries and energy storage solutions offer the most environmental flexibility in terms of project suitability is an important advantage in the ability to successfully deploy more storage in more locations in the United States and around the world.

Market shifts

Driven by both typical indoor space constraints (in both residential and commercial properties) as well as the frequent desire to co-locate storage and solar, more customers are seeking outdoor storage solutions.

In addition, the popularity of solar+storage and microgrid solutions is growing exponentially in industries such as agriculture, the military, medical care and disaster-related resiliency and recovery. Within these sectors, whether it be farms in Central California, military bases in the Middle East, or hurricane zones in the Caribbean and Florida, outdoor installations in hot climates are the rule, not the exception.

Temperature considerations by chemistry

Lead Acid

Lead acid batteries often have a fairly narrow temperature window and cannot function or offer long life cycles in cold or hot weather. For example, in equatorial climates lead acid batteries require replacement approximately every five years. These batteries also tend to have a storage capacity rated at 75℉ and the rated usable capacity can vary greatly when operating beyond this ideal temperature window.

Remember: Battery warranties often require operating within certain temperature parameters

Lithium-ion with cobalt

Lithium-ion batteries that contain cobalt — including NMC, LMO, NCA and LCO — require that the ambient temperature surrounding the batteries fall within a narrow window to protect the battery’s performance and warranty, with an upper limit of ~75℉. Maintaining this temperature requires expensive thermal monitoring and cooling equipment. Not only do the ancillary equipment costs negatively impact installation economics, these systems also introduce points of failure, including the risk of thermal runaway that can lead to overheating and fires.

Lithium-iron phosphate

Lithium-iron phosphate (also known as lithium ferrous phosphate or LFP) batteries generate very little heat during cycling, have no risk of thermal runaway and therefore do not require ventilation or cooling. In fact, some LFP batteries are warrantied to operate safely in environments up to 140°F without any ancillary temperature monitoring or maintenance equipment. These batteries often do not see efficiency or rating fluctuations when operating at low or high temperatures.

Enclosures

When it comes to outdoor battery banks, it is not only essential that the batteries are able to perform safely in a wide temperature range, but also that the containers and cabinets are able to withstand a wide range of environments. In the United States, this means looking for solutions that offer an outdoor enclosure with a rating of NEMA 3R or higher.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

— Solar Builder magazine

AC vs. DC coupling: Which is best for your application and why?

AC or DC coupling

AC or DC coupling refers to the way in which solar panels are coupled with and interact with a battery system. A hotly debated topic among solar installers today is whether AC or DC coupling is the best approach for solar+storage installations and retrofits. The truth is there really is no right or wrong answer. Both approaches have their merits, and the optimal approach depends entirely upon the application.

What is AC coupling?

AC coupled systems require two inverters: a common grid-tied solar inverter and a battery-based inverter. This means that the energy used by the batteries may be inverted as many as three times before being used in the home — i.e., from DC (PV array) to AC (load center) through the solar inverter, then back to DC (batteries) through the battery-based inverter, and then back to AC again (home loads). See Diagram 1 below.

Simpliphi Single line diagram AC coupling

Diagram 1

Small losses occur through each inverter, resulting in a reduction in overall system efficiency. Therefore, while AC coupled systems may be easier to install, using battery storage to cover AC loads is likely to result in a marginal decrease in efficiency.

However, AC coupled systems can be much more convenient for retrofits in which customers want to add batteries to existing residential grid-tied solar systems. One only needs to purchase an additional battery-based inverter to connect the batteries.

Because of the ease of installation, AC coupling can be ideal for grid-tied residential battery backup systems as well as large commercial systems, especially for retrofits where solar panels have already been installed.

What is DC coupling?

DC coupled systems use a charge controller to directly charge batteries with solar generation and a battery-based inverter to power home loads (AC). See Diagram 2 below.

Simpliphi Single line diagram DC coupling

Diagram 2

As a result, DC coupled systems are slightly more efficient than AC coupled systems because the power is not inverted multiple times. However, they often require more labor to install because the charge controllers tend to require smaller strings from the PV array.

When it comes to solar+storage retrofits, DC coupled systems present more challenges because the existing grid-tied solar inverter must be entirely removed and replaced with a battery-based inverter. In most cases, the existing PV array wiring will also need to be reconfigured.

DC coupling is ideal for new on- and off-grid solar+storage system installations in both residential and small commercial applications, but not retrofits with existing solar panels.

Sum it up: Pros and cons of AC and DC coupling

AC coupling pros:

  • Get to keep grid-tied inverter
  • Easier installation, especially for retrofits

AC coupling cons:

  • Less efficient
  • Less system functionality

DC coupling pros

  • More efficient
  • More regulated charging

DC coupling cons:

  • Not ideal for retrofits
  • Longer installation time

There are many factors that determine whether AC or DC coupling is best suited to a given application, so it’s important to understand the particular conditions and constraints of each project. Be sure consult with the battery manufacturer and/or the inverter manufacturer(s) to help you design the best energy system that optimizes the cost and performance of all the equipment for your particular project.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

— Solar Builder magazine