By Alison Brown, president, Flux Energy Systems
With many solar companies getting involved in storage projects, it is crucial that the project team understands the differences between the two technologies. Good project managers use their previous solar experience to anticipate risks that could derail their commercial solar-plus-storage budgets and schedules. The Flux Energy Systems team has worked on hundreds of solar projects and dozens of battery projects. Through that work, we have identified how key differences in the technology shape critical project decisions.
Of the utmost importance is that the site team understands the new safety implications of working with batteries. For instance, batteries can still generate electricity at night, are sometimes made of hazardous chemicals and can pose fire risks. Of course, working on a solar project requires extreme caution, but the hazards with storage are different. Anyone beginning to work with a new technology should devote extra time to learning safe work practices.
The fundamental value of a behind-the-meter solar PV project is almost always the cost of solar-generated electricity relative to that purchased from the utility. Given the control one has over the charge/discharge pattern of a battery, these systems have a much more complex value proposition, including peak shaving and energy arbitrage, among other features. The project manager should understand the financial drivers to make sure the interconnection application, customer expectations and project goals are aligned. Even the timing of project maintenance must be carefully considered to ensure the customer receives maximum value.
Like PV, batteries can be made up of a variety of materials. A good project manager should know what technology is being used as well as the associated risks, including fire damage, availability, manufacturing location and environmental effects of the battery system throughout its lifecycle. This will help them anticipate delays associated with permitting and supply chains, as well as cost increases associated with tariffs.
Both solar and battery projects make energy. When designing a solar project, a designer has some ability to impact the energy production of a solar project (e.g., changing the AC to DC ratio, module tilt or MPPT optimization), but ultimately the sun and the weather determine how much energy will be generated. That’s why the solar industry sizes systems by their nameplate power (MW) rather than their energy (MWh). Battery energy capacity, on the other hand, is entirely dependent on the quantity of batteries purchased, while power is defined by both the battery and the inverter. The more battery packs in parallel, the more energy stored. Since the energy capacity defines many of the rebates, financing programs and customer expectations, the project manager should understand the relationship between power and energy.
Energy flow: bidirectional vs. unidirectional
A solar project manager is already used to buying bidirectional breakers for a solar project, but they can’t forget that a battery needs to be charged and discharged. The electrical engineer must consider the impact of bidirectional power flows and perform load flow studies when necessary.
The energy density of a battery is much higher than that of a solar photovoltaic module. This results in a significant benefit: material handling seems simple to an experienced solar project manager! They are no longer dealing with thousands of solar modules. Instead, they just need to coordinate space for a handful of battery packs. This means there is a drastic reduction in site traffic, required laydown area and equipment delivery time frames.
Civil and structural engineering
Typically a rooftop solar project has limited civil and structural design. A structural engineer will need to confirm that the roof can bear the additional loads and may need to design an equipment pad foundation. For battery installations, civil and structural design work becomes a much larger portion of the project because batteries are heavy. Consequently, the pad and the foundation need to be evaluated more thoroughly than on a solar project. The PM should allot time to complete this work and work with an engineer who can deliver these designs.
Battery technology is evolving rapidly. Scroll through recent press releases to see regular announcements that the same amount of energy storage can be provided within a smaller footprint. This is no different from solar projects — frequently, a PM won’t know the exact DC wattage of a project until it is installed. Apply those same best practices on a battery project — submit the interconnection application for the largest possible AC power, submit for permits with the largest possible footprint, and maintain customer expectations that things may change depending on the evolving supply of technology.
Storage is the future, so commercial solar project managers will benefit by taking the steps necessary to offer these advanced systems.
Alison Brown, PE, PMP, has over 12 years of experience in renewable energy. She has worked with solar, battery, electric vehicle, fuel cell and smart grid technologies on projects ranging from remote, off-grid mountain cabins to industrial microgrids. In 2016, Alison founded Flux Energy Systems to streamline the design and integration of alternative energy projects. She and her team are working on solar, battery and EV charging station projects all over California.