The perils and promise of 1500 volt solar systems

Contributed by: Will White, Solar Application Specialist at Fluke | 1500 volt solar PV systems were unheard of when I entered the solar industry almost two decades ago. Since then, system components have steadily increased in power and efficiency; the similar size module that could have only generated 175 Watts 20 years ago can often generate 300 Watts now. And not a moment too soon: utility-scale solar system developers are increasingly expected to help satisfy skyrocketing demands for power.

Compared to older modules, the same number of high-efficiency modules can generate more power with fewer strings, wiring, fuses, fuse holders, and combiner boxes. These efficient components allow us to cost-effectively build high-voltage solar systems – even up to 1500 volts – with fewer components and less installation labor. This increased voltage at the same current level results in a lower percentage of voltage drop, along with reductions in labor time and expense. So 1500-volt systems can be optimized for the most cost-effective system design, while still ensuring quality components and proper installation.

However, increased voltage also heightens the risks – to both the system and its operators – associated with transient voltage spikes and other electric events. Since power is voltage multiplied by current, a 50% increase in voltage – for instance, a 1500 volt system compared to a traditional 1000 volt one – brings higher power and greater safety hazards.

And solar system voltage hasn’t maxed out yet: future solar installations are predicted to increase to 2000 volts. To ensure the safety of 1500+ volt solar systems and maximize their vast potential, it’s essential to choose specialized components, tools, and processes that are designed, certified, and third-party tested for high-voltage solar systems.

Designing for high voltage

First, verify that all system components are rated for 1500 volts or higher: wiring, modules, interconnections between modules, fuse holders, fuses, circuit breakers, disconnects, combiner boxes, and inverters.

Safety considerations for 1500 volt solar systems include following Article 691 of the National Electrical Code for Fire Prevention, which applies to all solar installations with inverter generating capacity of over 5000 kW that aren’t exclusively utility-owned. For solar systems paired with lithium-ion storage batteries, operators should utilize all applicable safety considerations and fire suppression equipment for flammable battery chemistries.

1500 volt testing tools

While many operators are aware of high-voltage system component considerations, an equally critical standard can be easily overlooked: the testing tools used to build and maintain these systems. These tools require higher minimum insulation levels based on the increased solid insulation, clearance (shortest air gap distance), and creepage (shortest surface distance) needed to protect the technician from electric shock and internal circuits from fire or arc fault.

Because of this need for increased distances within the tool, safe testing and measurement tools for 1500-volt systems must be larger than those designed for 1000 volt systems. But since 1500 volt systems are a relatively recent development, many testing and measurement tools on the market have been designed for lower-voltage solar systems. So, it’s all too easy to end up using a tool that doesn’t provide the necessary insulation levels to guarantee safety in high-voltage environments.

To find safe and accurate measurement tools for 1500+ volt solar systems, look at the tool’s specifications for its International Electrotechnical Commission (IEC) voltage rating. This rating is based on proximity to the power source and the tools ability to withstand a dangerous transient voltage spike. Avoid tools that only have a 1000 IEC voltage rating; even if they’re capable of measuring up to 1500 volts, they don’t ensure the technician’s or the systems’ safety at that voltage level.

In addition, verify that the tool has been third-party tested to the IEC standard at a 1500-volt level – not merely tested in-house, or only up to 1000 volts.

Following these guidelines helps ensure that the instrument and operator are never the weak link in the system — and subsequently the location of failure — in the event of a voltage transient. By prioritizing safety, selecting appropriate components and tools, and following best practices for high-voltage systems, we can harness their full potential while safeguarding both them and the technicians who work on them.

— Solar Builder magazine

[source: https://solarbuildermag.com/featured/the-perils-and-promise-of-1500-volt-solar-systems/]