Start with the Right Approach: Energy and Resilience Audit
Before diving into system design, start with an energy and critical-load audit. Determine:
- Total electricity usage (kWh/month and kW demand).
- Critical systems that must run during outages (e.g., control systems, tower lighting, water pumps).
- How long those systems must operate on backup (4 hours, 12 hours, 24 hours, or more).
This defines the system’s solar size and battery storage capacity, and helps determine if existing diesel generators can be supplemented or partially replaced.
Solar as a Backup to Diesel Generators
Many water treatment and pumping facilities rely on diesel generators during grid outages. While diesel generators provide reliable power, they have some limitations:
- Fuel logistics: During hurricanes, flooding, or other extreme events, diesel delivery may be delayed or impossible.
- Operational cost: Diesel is expensive and subject to price volatility.
- Maintenance and emissions: Generators require regular maintenance and produce emissions during operation.
Solar + battery storage can provide several advantages:
- Reduce generator runtime: Batteries can cover critical loads immediately, reducing diesel use and fuel consumption.
- Extend autonomy: Even small solar arrays paired with storage can allow generators to last longer, critical during hurricanes or extended outages.
- Immediate resilience: Unlike diesel deliveries, solar energy is on-site and unaffected by disrupted supply chains.
- Cost savings: Less diesel use translates to lower fuel costs and maintenance frequency.
Real-world example: During Hurricane Florence (2018), several utilities on the U.S. East Coast struggled with diesel delivery to backup generators. Facilities with battery + solar microgrids were able to maintain critical water pumping for hours without refueling.
Battery Sizing Basics (with Real Examples)
Formula:
Battery capacity (kWh) = Critical load (kW) × Hours of autonomy × (1 ÷ usable DoD) × (1 ÷ system efficiency)
Where:
- Usable DoD (Depth of Discharge) ≈ 0.8
- System efficiency ≈ 0.9
Example 1: Regional Airport Backup
- Critical load: 150 kW (lighting + comms)
- Autonomy: 4 hours
Result → ~850 kWh battery system
Example 2: Medium Water Treatment Plant
- Critical load: 500 kW
- Autonomy: 24 hours
Result → ~16 MWh battery system
Tip: Batteries can be sized to partially offset diesel load, covering essential systems until fuel resupply is available or extending generator runtime during prolonged events.
Design Approach: Build in Stages
- Stage 1: Solar Only
Offset daytime loads and reduce power bills immediately. - Stage 2: Add Battery Backup
Install battery storage to handle short-term outages and supplement existing diesel generators. - Stage 3: Full Microgrid Integration
Combine solar, batteries, and smart controls to enable full islanding during emergencies.
This phased approach keeps costs manageable and allows for scaling as technology and incentives evolve.
Where to Find Financing and Grants
1. FAA Airport Improvement Program (AIP) and Discretionary Grants
The FAA funds infrastructure and sustainability projects, including solar farms, EV charging, and electrification. Recent grants have gone to airports in Arizona, North Carolina, and Georgia for solar installations. For more information, visit the FAA’s official website: FAA Grants.
2. EPA Clean Water and Drinking Water State Revolving Funds (CWSRF/DWSRF)
These programs provide low-interest loans or principal forgiveness for eligible energy projects at public utilities. Many water treatment facilities have used these to install on-site solar + battery systems to supplement or replace partial diesel generator use. Learn more here: EPA CWSRF.
3. USDA REAP (Rural Energy for America Program)
For rural communities and utilities, REAP offers up to 50% grants and loan guarantees for renewable energy projects, including solar and battery storage. More details can be found at: USDA REAP.
4. Federal Investment Tax Credit (ITC)
Public-private partnerships or third-party PPAs can use the 30% federal ITC plus bonus credits for domestic content or energy communities.
5. State and Local Incentives
Programs vary, but utilities and states may offer additional rebates or net-metering benefits. Always check DSIREusa.org for current opportunities.
Cost Snapshot (for Planning)
| Project Type | Solar Size | Approx. Cost | Battery Add-On | Payback (with Grants) |
| Small airport (1 MW) | $1.2M – $1.6M | +$400K–$800K for BESS | 8–12 years | |
| Medium water plant (3 MW) | $3.5M – $4.5M | +$1.5M–$2.5M for BESS | 10–15 years | |
| Large airport (5 MW+) | $6M+ | +$3M+ for BESS | 12–18 years |
(Actual costs vary by site, land prep, and interconnection needs.)
Key Steps to Move Forward
- Conduct an energy and critical load study
- Identify which loads can be supported by solar + batteries to reduce diesel runtime
- Engage FAA (airports) or state agencies early for compliance and funding readiness
- Get quotes from EPCs or solar developers experienced in public infrastructure
- Apply for grants/loans through FAA, EPA, or USDA programs
- Build in phases to balance budget, resilience, and ROI
Final Thoughts
Combining solar + battery storage with existing diesel generators transforms emergency resilience for water utilities and airports. By reducing diesel dependency, extending generator runtime, and providing instant power during storms or hurricanes, these systems make critical infrastructure more reliable, cost-efficient, and sustainable.
Even partial solar + battery setups can ensure facilities maintain essential services when fuel supply chains are disrupted — a lesson reinforced during recent hurricanes.
Learn more at ricksq.live/bvpower-solar