Off-Grid Power Glossary
Plain-language definitions of the terms you will encounter when evaluating off-grid power systems. Each definition links to the relevant Clear Blue product or resource guide where applicable.
Autonomy Days
The number of days a battery system can power the load with zero solar generation. A telecom site typically needs 3-5 autonomy days. More autonomy days means a larger, more expensive battery bank, which is why smart load management is valuable: it maintains uptime with fewer autonomy days by actively managing energy reserves.
Cloud Energy Management
Using a cloud-connected platform to monitor, control, and optimize off-grid power systems remotely. Instead of sending a technician to check on a site, the operations team can see battery health, solar generation, and load data in real time from anywhere. Clear Blue's Illumience platform is a cloud energy management system purpose-built for off-grid power.
Learn about IllumienceDepth of Discharge (DoD)
The percentage of a battery's total capacity that has been used. A battery at 70% DoD has used 70% of its stored energy. Different battery chemistries have different safe DoD limits. LiFePO4 batteries can safely discharge to 80-90% DoD. Lead-acid batteries should not go below 50% DoD. Exceeding safe DoD shortens battery life.
Diesel Displacement
Reducing or eliminating diesel generator runtime by adding solar panels and batteries to a site. A well-designed hybrid system can reduce diesel runtime by 70% or more while maintaining the same uptime. The generator activates only during extended periods of low solar generation.
Read the diesel displacement guideEnergy as a Service (EaaS)
A model where the power provider owns, installs, monitors, maintains, and replaces the off-grid power system. The customer pays a fixed monthly fee instead of buying hardware. All performance risk sits with the provider. Clear Blue's EaaS includes 24/7 Illumience monitoring, proactive maintenance, and hardware replacements for the life of the agreement.
Explore EaaSHybrid Power System
An off-grid power system that combines two or more energy sources, typically solar panels, batteries, and a diesel generator or grid connection. The controller manages the interplay between sources to minimize fuel use and maximize uptime. Clear Blue's Micro system supports three independent power inputs.
See Micro hybrid powerLiFePO4 (Lithium Iron Phosphate)
A lithium battery chemistry widely used in off-grid power because of its long cycle life, thermal stability, and safety. LiFePO4 batteries can handle 3,000-5,000 charge cycles compared to 500-1,000 for lead-acid. They are more expensive upfront but last 2-3 times longer, making them cheaper over the system lifetime. Clear Blue uses LiFePO4 batteries in all its power products.
Low Voltage Disconnect (LVD)
A protection feature that automatically disconnects the load when battery voltage drops below a safe threshold. This prevents deep discharge that would permanently damage the battery. Clear Blue systems use two-level LVD: a software-controlled smart disconnect managed by Illumience, backed by a hardware failsafe.
MPPT (Maximum Power Point Tracking)
A technique used by solar charge controllers to extract the maximum possible power from solar panels under varying conditions. As sunlight, temperature, and shading change throughout the day, the optimal operating point of the panel shifts. An MPPT controller continuously adjusts to find that point, typically harvesting 20-30% more energy than a non-MPPT controller.
Off-Grid Power
Generating and storing electrical power at a location that is not connected to the utility grid. Off-grid systems typically use solar panels, wind turbines, or diesel generators combined with battery storage. The key challenge is reliability: without the grid as a backup, the system must generate and store enough energy to cover every hour of every day, including the worst weather weeks of the year.
Read the planning guidePeak Sun Hours (PSH)
A way to express the solar energy available at a location. One peak sun hour equals 1,000 watts per square meter of sunlight for one hour. A location with 5 PSH per day receives enough sunlight to run a solar panel at its rated output for 5 hours. PSH varies dramatically by location (2-3 in northern winters, 6-7 near the equator) and is the starting point for system sizing.
Predictive Maintenance
Using data and analytics to predict when a component will fail and scheduling maintenance before it causes downtime. In off-grid power, this means tracking battery degradation curves, solar panel performance trends, and weather forecasts to identify problems weeks before they affect the site. Illumience provides predictive maintenance for every system in the fleet.
See how Illumience predicts failuresRemote Monitoring
Continuously tracking the performance of off-grid power systems from a central location using cellular, satellite, or mesh communications. Effective remote monitoring covers battery state of charge, temperature, solar generation, load consumption, and communication uptime. Without it, failures are discovered only when the site goes dark.
Read the monitoring guideSmart Load Management
Intelligently controlling which loads are powered and when, based on available energy, battery state, and weather forecasts. During low-generation periods, non-critical loads can be temporarily shed to preserve power for critical equipment. Clear Blue's systems use smart load management to maintain uptime with 30-50% smaller batteries than conventional designs.
See Nano's smart load controlState of Charge (SoC)
The current charge level of a battery expressed as a percentage of its total capacity. A battery at 80% SoC has 80% of its usable energy remaining. Monitoring SoC in real time is essential for off-grid systems because it tells you how much runway the site has before the load must be shed or a backup generator activated.
State of Health (SoH)
A measure of a battery's overall condition compared to its original specifications. A new battery has 100% SoH. As it ages through charge-discharge cycles, SoH decreases. When SoH drops below 80%, the battery can no longer reliably carry the site through low-generation periods and should be replaced.
Track SoH with KPIsTemperature Derating
The reduction in battery capacity or solar panel output caused by operating outside the optimal temperature range. LiFePO4 batteries lose significant capacity below 0C and cannot charge below -10C. Solar panels lose about 0.4% output per degree above 25C. Any accurate system sizing must account for temperature derating at the specific deployment location.
Total Cost of Ownership (TCO)
The complete cost of a power system over its full lifetime, including hardware, installation, maintenance, battery replacements, monitoring, internal labor, and downtime. TCO is the only honest way to compare buy-and-own against Energy-as-a-Service, because the upfront hardware cost is typically less than half of the 10-year total.
Read the TCO comparisonTurnkey System
A power system that arrives pre-configured and ready to install without custom engineering at the site. Clear Blue's Nano and Pico product lines are turnkey systems: they ship configured for the site's GPS coordinates and install in hours. This is the opposite of a bespoke system that requires on-site design, wiring, and commissioning by specialized engineers.
Have a Term We Should Add?
If you are evaluating off-grid power and have a question about terminology, our engineering team is happy to help.