Guide Introduction
Solar PV and battery storage can reduce energy costs, improve resilience and support long-term energy planning. However, every site is different, and system performance depends on the load profile, roof layout, shading, inverter selection, battery autonomy and municipal requirements.
This guide provides practical planning guidance for understanding solar PV systems, hybrid battery storage, PV*SOL modelling, SSEG requirements and key design considerations before selecting a solution.
1. Solar PV System Types
Grid-tied solar
- Typical use
- Sites with reliable grid supply looking to reduce daytime energy costs.
- Advantages
- Efficient, cost-effective and well suited to daytime commercial consumption.
- Limitations
- Usually does not provide backup power without additional equipment.
- Backup capability
- No backup unless paired with storage or backup integration.
Hybrid solar with battery storage
- Typical use
- Sites needing energy savings plus backup for selected essential loads.
- Advantages
- Combines PV generation, storage and backup capability.
- Limitations
- Requires careful inverter, battery and compliance design.
- Backup capability
- Can support selected backup circuits depending on battery and inverter capacity.
Off-grid solar
- Typical use
- Remote sites or applications without practical utility supply.
- Advantages
- Independent power supply when designed with sufficient storage and backup generation.
- Limitations
- Higher storage and redundancy requirements; detailed load analysis is essential.
- Backup capability
- Designed as the primary supply with storage and often generator support.
Solar-assisted backup systems
- Typical use
- Existing backup power systems where solar and batteries reduce generator runtime or grid dependency.
- Advantages
- Improves resilience and can reduce diesel or grid energy consumption.
- Limitations
- Integration with generators, UPS systems and controls must be carefully planned.
- Backup capability
- Supports backup strategy when correctly integrated with critical loads.
2. Understanding Solar Yield
Solar yield is the expected energy production from a PV system. It is affected by PV array size in kWp, peak sun hours, performance ratio, roof orientation, tilt, shading, soiling, cable losses, temperature losses, inverter efficiency and seasonal variation.
3. Inverter Sizing and DC/AC Ratio
The inverter AC capacity determines the maximum AC output, while the PV array DC capacity is the installed solar module capacity. The DC/AC ratio compares these values and helps assess whether the PV array is appropriately matched to the inverter.
PV arrays are sometimes larger than inverter output to improve production across the day, but MPPT limits, voltage/current limits and clipping must be checked against manufacturer data.
4. Battery Storage and Backup
Battery storage is normally planned in kWh, with usable battery capacity determined by the battery technology, depth of discharge, battery management system and inverter compatibility. Lithium 48V, lithium HV and lead-acid systems all behave differently and must be selected around the application.
Backup design should separate essential loads from non-essential loads. Whole-site backup can require substantially larger inverter and battery capacity than essential-load backup.
5. Load Profiles and Self-Consumption
Daytime load profile is central to solar feasibility. Commercial sites often benefit from daytime solar use because energy consumption occurs while the PV system is producing. Residential sites may need batteries to shift solar energy into evening loads.
Self-consumption, export limits, demand charges and tariff structures should be considered together. Monitoring data improves design accuracy and helps avoid oversizing around monthly energy bills alone.
6. PV*SOL Modelling
Emerald uses PV*SOL for professional solar design where required. PV*SOL can model roof layout, shading, yield, module strings, inverter configuration and long-term energy output.
Online calculators are preliminary only. PV*SOL improves design confidence before final proposals by modelling site-specific constraints and equipment selections.
7. SSEG and Municipal Requirements
Small-Scale Embedded Generation requirements apply to many grid-tied and hybrid systems. Municipal approval may be required, and compliance documentation can include inverter approvals, single-line diagrams, engineer sign-off, export limiting, metering and utility-specific requirements.
SSEG requirements should be reviewed early because they can affect equipment selection, grid interaction, protection settings and project timelines.
8. Installation Considerations
9. Maintenance and Monitoring
Solar and battery systems need ongoing inspection and monitoring to maintain performance. This includes visual inspections, cleaning, inverter alarm review, battery health checks, thermal checks and performance comparison against expected yield.
Monitoring portals help identify underperformance, inverter faults, communication failures and battery issues before they become operational problems.
10. Common Solar Design Mistakes
11. When to Speak to a Critical Power Specialist
If a solar or battery system is intended to support business continuity, critical loads, hybrid backup, generator integration or long-term energy cost reduction, the design should be reviewed by an experienced Critical Power Specialist before procurement or installation.
Speak to a Critical Power SpecialistDisclaimer and Copyright
This guide is provided for general technical guidance only. Final solar PV design, battery sizing, inverter selection, SSEG requirements, protection, cable sizing and installation requirements must be confirmed against manufacturer data, site conditions, PV*SOL modelling, SANS requirements, municipal requirements and applicable regulations.
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