Off-Grid Power System Planning

NPPT personnel have a long history and deep experience in engineering for off-grid systems supplied by renewables backed up by generators, and including energy storage, and serving critical or noncritical loads. One thing that makes NPPT unique is that NPPT can provide both the planning aspects, and the detailed engineering such as protection,arc flash, and control dynamics analyses. Aspects of off-grid system engineering we cover include:

  • Capacity and  adequacy  planning,  to  meet  cost-constrained  loss  of  load  probability  targets and considering locally-available  resources  including  wind,  sun,  and  This includes  load assessment for existing loads and load forecasting for not-yet-existing loads.
  • Load analysis to  assist  in  improving  efficiency  and  minimizing  electrical  demand without sacrificing load function.
  • Design and specification of off-grid power system components.
  • Deployment of off-grid power systems, including systems in difficult-to-reach locations.
  • Detailed electrical engineering services for off-grid plants, such as controls and dynamics studies, protection analysis, arc flash analysis, and custom controls designs and solutions, for centralized or distributed systems.
  • Monitoring and performance assessment of off-grid power systems, including problem diagnosis and resolution, and root-cause analysis of events.
  • Owner’s Engineer services in multi-stakeholder projects.

NPPT provides these services with an exceptional level of skill, professionalism, responsiveness, and creative but practical thinking. If you have a need that does not appear on this list, please contact us to discuss it.

Example projects

A brief listing of a few relevant recent projects includes the following.

Planning, design, specification, procurement, deployment and monitoring of multiple off-grid hybrid PV plants. For several smaller projects (typically less than 100 kW), NPPT personnel have performed essentially an EPC function, providing end-to-end system engineering services resulting in a turn-key off-grid power plant including generation, storage and PV.This included:
  • Assistance in obtaining funding
  • Load assessment, to identify consumption from existing and planned future load
  • Identification of design criteria
  • Sizing and specification of all system components
  • Delivery of components to the site
  • On-site assistance in building and commissioning the plant (using local electrician and constructionservices)
  • Ongoing field monitoring
All systems outperformed their expectations. NPPT personnel also provided follow-on support for the system operator, ranging from answering simple questions, to site visits to perform investigations, to helping one operator obtain replacement batteries after a less -experienced person fully discharged a set of lead-acid batteries during a winter of -40 o temperatures.
  • Design, testing, and monitoring of controls for a ~5 MW island grid. This project entailed design and deployment of controls for an energy storage plant designed to help stabilize voltage and frequency in a ~5 MW island grid experiencing high PV deployment levels (as much as 90% of the island power could come from PV on sunny, low-load days). The island had existing and somewhat aged generation plant that was not to be altered for the project. NPPT’s controller successfully met that need and is deployed today, although it has not been fully utilized because of some political and other considerations impacting the system operator.
  • Diagnosis of power quality problems in an off-grid hybrid PV power NPPT performed modeling, field measurements, and analysis to identify and correct a persistent flicker problem that was occurring in a ~ 200 kW diesel + PV +storage off-grid plant. NPPT correctly identified the problem and a minimum-cost solution, and continued to work with the plant operator until the problem was resolved.
  • Protection and arc flash analysis for a 1.2 MW off-grid diesel + PV + storage plant. NPPT designed, tested in simulation, and fully specified a protection system for this microgrid that maximally preserves coordination and minimizes loss of load probability, and then completed a related arc flash study including boundary and PPE determinations.
  • Efficiency analysis of a facility considering This project involved a facility with diesel generators in which large volumes of water are processed and pumped and that is located in an arid but sun-rich area. The facility owner wished to utilize PV, but the power demands of the site were extremely high. NPPT personnel analyzed the plant load and discovered that over half of the three-phase induction motors driving pumps in the facility were being utilized in a way that rendered them highly inefficient and that also caused them to consume much more reactive power than necessary. A more optimal motor design was identified that would reduce the facility’s pumping energy usage by over 30%.