Sizing a solar system for a business requires more than counting solar panels or choosing an inverter based on the size of the building.
A commercial solar installation must be designed around the business's actual electricity consumption, operating hours, peak demand, available roof space, electrical supply, battery requirements and future expansion.
A small shop, office, restaurant, hotel, school, workshop, warehouse and factory can all have completely different electrical requirements.
A business may consume most of its electricity during daylight, making direct solar consumption highly attractive. Another business may operate at night and require substantial battery storage. A factory may have large motors and compressors that create high starting currents. A hotel may have continuous refrigeration, water pumping, air conditioning and water-heating loads.
For professional commercial solar assessment, system sizing and installation in Kenya, contact 0723763173.
START WITH ENERGY
The first step is determining how much electricity the business actually consumes.
Electricity consumption is normally measured in kilowatt-hours, abbreviated as kWh.
A monthly electricity bill can provide useful information.
For example, if a business consumes approximately 3,000 kWh in a month, its average daily consumption can be estimated by dividing the monthly consumption by the number of days in the billing period.
However, the average daily value is only a starting point.
A business may consume very different amounts of electricity at different times of day.
DAILY CONSUMPTION
Daily energy consumption helps determine the approximate size of the PV array.
The designer should establish:
- Average daily consumption
- Highest daily consumption
- Lowest daily consumption
- Weekday consumption
- Weekend consumption
- Seasonal changes
- Daytime consumption
- Nighttime consumption
This information produces a much more realistic design.
LOAD PROFILE
A load profile shows how electricity demand changes over time.
Consider an office.
It may have low electricity demand early in the morning.
Demand increases after employees arrive.
It may remain high through the working day.
Demand falls after employees leave.
Solar generation follows a different pattern.
It rises after sunrise, reaches its stronger production period around the middle portion of the day and declines toward sunset.
If the office's electricity demand overlaps strongly with solar generation, a significant portion of PV energy can be consumed directly.
DAYTIME SOLAR
Daytime self-consumption is one of the most important concepts in commercial solar.
When solar energy is generated and immediately consumed by the business, there is no need to store that particular energy in a battery.
For example:
Solar production = 20 kW
Business load = 18 kW
Approximately 18 kW can be used directly by the loads, subject to system conditions.
The remaining available solar power may charge a battery or be managed according to the system architecture and applicable arrangements.
NIGHTTIME LOAD
A business with substantial nighttime consumption has a different solar-storage requirement.
Examples include:
- Hotels
- Restaurants
- Security facilities
- Cold rooms
- Entertainment venues
- Hospitals
- 24-hour operations
If solar is generated during the day but the business needs substantial electricity at night, battery storage or continued grid/generator supply may be required.
PEAK LOAD
Daily energy consumption does not determine inverter size by itself.
Peak load must also be considered.
A business might consume 500 kWh per day but have a peak instantaneous demand of 150 kW.
Another business might consume the same amount of energy with a peak demand of only 50 kW.
These two businesses may require different inverter capacities.
POWER VERSUS ENERGY
Power is measured in watts or kilowatts.
Energy is measured in watt-hours or kilowatt-hours.
Power tells you how much electricity is being used at a particular moment.
Energy tells you how much electricity is consumed over time.
This distinction is fundamental when designing commercial solar systems.
EXAMPLE LOAD
Suppose a workshop operates several machines.
The machines may have the following approximate ratings:
- Compressor: 15 kW
- Pump: 7.5 kW
- Lighting: 3 kW
- Office equipment: 2 kW
- Ventilation: 5 kW
If all of these operate simultaneously, the instantaneous demand could be substantial.
But if some machines operate at different times, the actual peak may be lower.
A proper load assessment therefore considers simultaneous operation.
ELECTRICITY BILLS
A business should provide several months of electricity bills where possible.
This helps identify:
- Average consumption
- Consumption trends
- Seasonal changes
- High-demand periods
- Changes in business activity
A single bill may not represent the normal operating pattern.
SMART METER DATA
Where detailed meter information is available, it can provide better insight into energy consumption.
The data may reveal:
- Hourly demand
- Peak periods
- Nighttime consumption
- Weekend demand
- Seasonal patterns
This can make solar sizing more precise.
LOAD MEASUREMENT
For larger commercial systems, actual electrical measurements can be valuable.
Measurements may include:
- Voltage
- Current
- Active power
- Reactive power
- Power factor
- Frequency
- Energy
The measurements should be performed by appropriately qualified personnel using suitable equipment.
PANEL CAPACITY
Solar panel capacity is commonly expressed in kilowatts peak, or kWp.
For example:
10 × 500 W panels = 5,000 W = 5 kWp
20 × 500 W panels = 10,000 W = 10 kWp
40 × 500 W panels = 20,000 W = 20 kWp
The PV capacity should be selected based on the energy target and site conditions.
SOLAR RESOURCE
The amount of energy produced by a PV system depends on available solar irradiance.
The actual production varies with:
- Location
- Season
- Cloud cover
- Panel orientation
- Panel tilt
- Shading
- Temperature
- Soiling
- System losses
A PV system should not be expected to produce its maximum rated power continuously throughout the day.
PEAK SUN HOURS
Solar designers often use an equivalent peak-sun-hours concept to estimate daily production.
For example, a PV system rated at 10 kWp does not normally produce 10 kW continuously for an entire day.
Instead, its daily energy production is estimated from the available solar resource and system losses.
A simplified conceptual calculation is:
Daily PV energy ≈ PV capacity × equivalent solar hours × system efficiency factor
The actual design should use appropriate site data and engineering assumptions.
SYSTEM LOSSES
Real solar systems experience losses.
These can occur through:
- Inverter conversion
- PV temperature effects
- Cables
- Connectors
- Soiling
- Mismatch
- Battery charging and discharging
- Other system components
A design should therefore not assume that all theoretical PV energy reaches the business loads.
PANEL NUMBER
Once the desired PV capacity has been established, the number of panels can be calculated from panel wattage.
For example:
10 kWp ÷ 0.5 kW per panel = 20 panels
If 450 W panels are used:
10 kWp ÷ 0.45 kW ≈ 22.2 panels
The actual design would use an appropriate whole number and then verify string configuration.
STRING DESIGN
Panel count is not the end of PV design.
Panels must be connected into strings compatible with the inverter.
The designer must check:
- Voc
- Vmp
- Isc
- Imp
- Maximum DC voltage
- Maximum input current
- MPPT voltage range
- Number of MPPTs
Incorrect string design can cause poor performance or equipment damage.
INVERTER SIZE
The inverter should be selected according to the business's electrical demand.
Important factors include:
- Maximum continuous load
- Surge requirements
- Motor starting
- Three-phase requirements
- Power factor
- Battery capacity
- PV input
- Future expansion
A business should not simply choose an inverter equal to the PV capacity.
PV AND INVERTER RATIO
It is possible in some systems to install more PV capacity than the inverter's nominal AC output.
For example, a manufacturer may permit a 50 kW inverter to accept a PV array larger than 50 kWp.
The purpose can be to increase energy harvesting during periods of lower irradiance.
However, the manufacturer's DC input limits must always be respected.
THREE-PHASE LOADS
Commercial buildings frequently use three-phase electricity.
Three-phase systems may supply:
- Motors
- Compressors
- Pumps
- Industrial equipment
- Large HVAC systems
The solar architecture must be compatible with the building's electrical system.
PHASE BALANCE
Phase imbalance can create problems in three-phase systems.
The designer should understand how major loads are distributed across the phases.
A commercial solar installation should integrate correctly with the existing electrical distribution system.
MOTOR LOADS
Motors require special attention.
Starting a motor can require substantially more current than normal running conditions.
Examples include:
- Borehole pumps
- Compressors
- Fans
- Workshop machinery
- Refrigeration compressors
The inverter must be capable of handling the relevant starting conditions or the system should use appropriate motor-control equipment.
VFD CONTROL
A variable-frequency drive can help control motor starting and operating speed.
In suitable applications, a VFD can:
- Reduce starting current
- Control speed
- Improve process control
- Reduce unnecessary energy consumption
VFD settings and compatibility should be evaluated as part of the overall electrical design.
BATTERY SIZING
Battery sizing depends on why the business wants storage.
A battery can be used for:
- Backup
- Nighttime energy
- Peak reduction
- Solar self-consumption
- Critical-load support
The required capacity differs significantly depending on the objective.
BACKUP BATTERY
If the battery is primarily for outages, determine:
- Which loads must remain operational?
- How much power do those loads require?
- How long must they operate?
- How much usable battery energy is required?
The simplified formula is:
Battery energy ≈ average backup load × required backup hours
Additional allowance is needed for efficiency, operating limits and design conditions.
CRITICAL LOADS
A business does not necessarily need to back up every electrical load.
Critical loads may include:
- Internet
- Security
- POS
- Refrigeration
- Emergency lighting
- Computers
- Communication equipment
Heavy production machinery may remain on grid or generator power.
This can substantially reduce battery requirements.
WHOLE-BUILDING BACKUP
If the business wants the solar system to supply the entire building during a grid outage, the inverter and battery requirements can become much larger.
Loads such as:
- Air conditioners
- Water heaters
- Ovens
- Pumps
- Compressors
- Motors
can consume substantial power.
Whole-building backup should therefore be engineered carefully.
BATTERY POWER RATING
Battery energy capacity is not the only consideration.
The battery also has maximum charge and discharge power.
A battery may have enough stored energy but still have insufficient power capability for a large load.
Battery and inverter specifications must therefore be matched.
BATTERY CHEMISTRY
Modern commercial installations may use lithium-based batteries, including LFP chemistry.
Advantages can include:
- High usable energy
- High efficiency
- Good cycling capability
- Low routine maintenance
- Integrated BMS
Other battery technologies remain possible depending on the project.
BATTERY BMS
The Battery Management System monitors and protects the battery.
It can monitor:
- Cell voltage
- Temperature
- State of charge
- Current
- Fault conditions
Battery communication with the inverter can improve system coordination where compatible.
BATTERY TEMPERATURE
Battery temperature can affect performance and lifespan.
Commercial batteries should be installed in appropriate environments according to manufacturer requirements.
Excessive heat should be avoided.
ROOF ASSESSMENT
The roof should be inspected before installing a large PV array.
The assessment should consider:
- Roof material
- Structural capacity
- Age
- Waterproofing
- Shading
- Access
- Drainage
- Maintenance
A large commercial roof does not automatically mean every part of it is suitable for solar.
PANEL LAYOUT
Panel layout should leave adequate space for:
- Maintenance
- Access
- Roof drainage
- Equipment
- Fire-safety requirements where applicable
Panels should not simply be installed across every available surface.
SHADING ANALYSIS
Shading from nearby buildings, trees and roof structures can reduce production.
A commercial site should be assessed at different times of day.
Shading may also change seasonally.
INVERTER LOCATION
The inverter should be located where:
- Ventilation is adequate
- Ambient temperature is appropriate
- Access is available
- Cables can be routed efficiently
- Water exposure is controlled
- Security is adequate
Long cable distances can increase voltage drop and installation costs.
BATTERY LOCATION
Battery placement should follow manufacturer and applicable safety requirements.
Consider:
- Temperature
- Ventilation
- Access
- Protection
- Fire safety
- Cable length
- Security
DC PROTECTION
A commercial PV system should have appropriate DC protection.
Depending on the architecture, this can include:
- DC isolators
- Surge protection
- String protection
- Suitable connectors
- Proper enclosures
AC PROTECTION
The AC side may require:
- Main isolation
- Circuit protection
- Surge protection
- Appropriate distribution equipment
The design should integrate with the existing commercial electrical system.
EARTHING
Proper earthing and bonding are important.
PV structures, inverter equipment and other metallic components should be integrated into an appropriate protective arrangement.
MONITORING
Commercial monitoring can show:
- PV production
- Load demand
- Grid consumption
- Battery status
- Energy trends
- Faults
This data can help management understand whether the solar system is meeting its objectives.
SOLAR SELF-CONSUMPTION
One of the most useful commercial solar metrics is self-consumption.
If the business uses most of the solar electricity as it is generated, the system can provide strong direct value.
For example:
PV production = 50 kWh
Business directly uses = 42 kWh
The remaining 8 kWh may be stored, exported where permitted, curtailed or otherwise managed depending on the system.
ENERGY OFFSET
The purpose of a commercial PV system may be to offset part of the business's grid consumption.
The desired offset might be:
- Small
- Moderate
- High
The appropriate PV size depends on the business's energy use and available installation area.
NOT EVERY BUSINESS NEEDS 100% SOLAR
A business does not necessarily need to generate all its electricity from solar.
A system may be designed to offset a portion of consumption.
For example, a business could install solar to reduce daytime grid consumption while retaining the grid as a reliable supplementary source.
This may be more economical than attempting complete energy independence.
HYBRID SYSTEM
A hybrid system combines solar and battery storage with another energy source.
For a commercial building, that may be:
Solar + Battery + Grid
or:
Solar + Battery + Grid + Generator
The system can be configured according to the business's priorities.
OFF-GRID BUSINESS
An off-grid commercial property requires more careful energy planning.
Without grid electricity, the system must provide sufficient energy through:
- Solar
- Battery
- Generator where applicable
The PV array and battery must be sized for the expected demand and periods of low solar production.
GENERATOR BACKUP
Businesses that already own generators can integrate solar and battery storage into a broader energy strategy.
The generator may operate during:
- Extended outages
- Prolonged cloudy periods
- Very high loads
- Battery depletion
The integration must be engineered correctly.
SOLAR AND REFRIGERATION
Refrigeration is an important commercial load.
Examples include:
- Supermarkets
- Butcheries
- Restaurants
- Hotels
- Cold rooms
- Food-processing businesses
Because refrigeration can operate continuously, its daily energy consumption should be measured carefully.
SOLAR AND AIR CONDITIONING
Air conditioning can be one of the largest loads in commercial buildings.
Solar production can coincide with cooling demand during daytime.
This makes air conditioning a potentially good daytime solar load.
However, the inverter must be sized for the equipment's operating and starting characteristics.
SOLAR AND WATER PUMPS
Commercial water pumps can consume substantial energy.
Solar can be used to:
- Pump borehole water
- Fill storage tanks
- Supply irrigation
- Operate booster systems
Where practical, pumping can be scheduled during solar production.
SOLAR AND ELECTRIC COOKING
Restaurants, hotels and food-processing businesses may use electric cooking equipment.
High-power heaters can create significant peak demand.
The system should consider whether these loads should operate directly from solar, from grid electricity, or through a combination.
SOLAR AND WATER HEATING
Commercial hot-water requirements can be substantial.
Hotels and institutions may benefit from solar thermal water heating in addition to photovoltaic electricity.
Reducing electrical water-heating demand can reduce the PV capacity needed.
ENERGY EFFICIENCY
Before increasing solar capacity, consider reducing energy waste.
Possible measures include:
- LED lighting
- Efficient motors
- Efficient refrigeration
- Efficient air conditioning
- VFDs
- Automatic controls
- Timers
- Improved insulation
Efficiency improvements can reduce the size of the required solar system.
FUTURE LOADS
Businesses change.
A company may add:
- New machinery
- Additional offices
- More refrigeration
- Air conditioning
- Electric vehicles
- Extended operating hours
The solar architecture should allow sensible expansion where practical.
BUSINESS GROWTH
A modular system can sometimes be preferable.
For example, a business may install an initial PV array and inverter capacity and later add additional equipment.
The original system should be designed with expansion limits in mind.
SMALL SHOP
A small shop might require solar for:
- Lighting
- Refrigeration
- POS
- Internet
- CCTV
A relatively modest PV and battery system may be adequate.
The final size should still be based on actual measurements.
RESTAURANT
A restaurant may require:
- Refrigeration
- Cooking
- Lighting
- Water heating
- Ventilation
- Air conditioning
- POS
The cooking equipment can dominate peak demand.
HOTEL
Hotels have complex load profiles.
They may use electricity for:
- Guest rooms
- Kitchen
- Laundry
- Hot water
- Pumps
- Refrigeration
- Air conditioning
- Lighting
A combination of PV, battery storage and solar water heating can be considered.
OFFICE BUILDING
Office buildings often have significant daytime loads.
Solar can supply:
- Lighting
- Computers
- Networking
- Printers
- Air conditioning
- Office equipment
Battery storage can provide backup to critical systems.
SCHOOL
Schools may consume electricity during daytime teaching hours.
Solar can support:
- Classrooms
- Computer laboratories
- Administration
- Security
- Internet
- Water pumping
Boarding schools may require additional nighttime energy.
WORKSHOP
Workshops often have motors and heavy tools.
The designer should identify:
- Motor ratings
- Starting methods
- Operating schedules
- Simultaneous loads
A simple residential inverter may not be appropriate.
FACTORY
Factory solar systems require industrial load analysis.
The designer may need to evaluate:
- Transformers
- Motors
- VFDs
- Compressors
- Production equipment
- Welding
- Heating
- Lighting
Large systems may require multiple inverters.
WAREHOUSE
Warehouses can have large roof areas suitable for PV.
The main electrical loads may include:
- Lighting
- Security
- Office equipment
- Refrigeration
- Material-handling equipment
Roof structural assessment remains important.
SOLAR FOR APARTMENTS
Apartment buildings may use solar for common services such as:
- Water pumps
- Security
- Lighting
- CCTV
- Gates
The design should distinguish common-area consumption from individual tenant consumption.
SOLAR FOR FARMS
Farms can use commercial-scale solar for:
- Borehole pumping
- Irrigation
- Dairy operations
- Poultry
- Cold storage
- Processing
- Security
The system should account for seasonal agricultural activity.
SOLAR FOR COLD STORAGE
Cold storage may require continuous energy.
A hybrid system with battery backup can improve resilience.
However, the battery must be sized according to the actual refrigeration load and desired backup duration.
SOLAR FOR INDUSTRIAL PUMPS
Large pumps require careful electrical engineering.
The designer should evaluate:
- Pump motor
- Starting current
- Operating head
- Flow
- VFD
- Daily operation
- Solar resource
Solar PV capacity alone does not determine pumping performance.
SOLAR FOR ELEVATORS
Commercial buildings may have elevators.
Elevators can create short-duration high-power demands.
The solar inverter and backup architecture must be assessed carefully if elevators are to operate during outages.
SOLAR FOR SERVERS
Servers and network systems may require uninterrupted power.
Solar can support the overall building, while UPS and battery systems can provide immediate continuity.
The electrical architecture should be coordinated.
SOLAR FOR SECURITY
Security loads are often suitable for backup.
They can include:
- CCTV
- Electric fence
- Alarm systems
- Access control
- Gate motors
- Security lighting
These loads should be included in the essential-load design.
POWER QUALITY
Commercial equipment can be sensitive to:
- Voltage fluctuations
- Frequency changes
- Harmonics
- Surges
- Poor power quality
Solar inverters and electrical equipment should be selected appropriately.
HARMONICS
Modern electronic loads can introduce harmonic currents.
Commercial and industrial systems may require power-quality assessment.
The designer should consider the effects of nonlinear loads on the electrical network.
TRANSFORMERS
Large commercial properties may have transformers.
Solar integration at transformer-connected facilities requires careful consideration of:
- Transformer capacity
- Protection
- Voltage
- Phase configuration
- Grid interaction
- Power flow
Large installations may require specialized engineering.
MAIN DISTRIBUTION BOARD
The main distribution board is an important part of the solar integration.
The installer should assess:
- Available breaker space
- Busbar capacity
- Main supply
- Cable sizes
- Protection
- Earthing
- Phase configuration
A solar system should not simply be connected to an unsuitable distribution board.
CABLE DISTANCE
Long cable runs can increase:
- Voltage drop
- Cable cost
- Installation complexity
Inverter and battery locations should therefore be selected carefully.
SOLAR ARRAY SECURITY
Commercial solar arrays can represent significant capital assets.
Security considerations may include:
- Secure mounting
- Restricted access
- CCTV
- Fencing
- Tamper-resistant hardware
The appropriate measures depend on the site.
WEATHER
Commercial solar systems operate outdoors and must withstand environmental conditions.
The installation should consider:
- Rain
- Wind
- Dust
- Heat
- Humidity
- Corrosion
Coastal properties may require additional corrosion considerations.
CLOUDY WEATHER
Solar panels continue generating electricity during cloudy weather, although output generally decreases.
Commercial systems should be designed with realistic solar-resource assumptions rather than assuming maximum output every day.
Battery and grid support can help manage periods of reduced PV production.
RAIN
Rain does not automatically stop solar generation.
Available light still reaches the panels.
Heavy cloud associated with storms can significantly reduce output.
The system should continue operating within its designed electrical limits.
MAINTENANCE
Commercial solar systems should have a maintenance plan.
Tasks can include:
- Panel cleaning
- Visual inspection
- Electrical inspection
- Mounting inspection
- Inverter checks
- Battery checks
- Monitoring review
- Protection inspection
PERFORMANCE CHECKS
The business should monitor whether the solar system is producing as expected.
Unexpected reductions may indicate:
- Dirt
- Shading
- Faulty strings
- Inverter problems
- Cable issues
- Module problems
Historical data is useful for identifying trends.
SYSTEM DOCUMENTATION
A commercial solar project should be properly documented.
Useful documentation includes:
- PV layout
- String design
- Equipment models
- Inverter settings
- Battery details
- Electrical diagrams
- Protection arrangements
- Maintenance information
- Warranty documentation
PROFESSIONAL INSTALLATION
Commercial solar is an electrical infrastructure project.
It should be designed and installed by appropriately qualified professionals.
The installation should follow applicable electrical and safety requirements.
PRO-LOGIC TECHNOLOGIES LIMITED
Pro-Logic Technologies Limited provides solar and electrical solutions for businesses, commercial buildings, farms, workshops, institutions and industrial applications in Kenya.
A commercial solar project can include:
- Solar PV installation
- Hybrid solar systems
- Three-phase solar
- Battery storage
- Inverter installation
- Solar water pumping
- Borehole pumping
- VFD integration
- Electrical protection
- Monitoring
- Maintenance
The system should be designed from actual energy data rather than an arbitrary package.
For commercial solar system sizing, installation, hybrid solar, battery backup and business energy solutions in Kenya, contact:
0723763173
FINAL ANSWER
Sizing a solar system for a business begins with the electrical load.
The correct process is:
MEASURE ENERGY → ANALYZE LOAD PROFILE → DETERMINE PEAK DEMAND → SIZE PV → SIZE INVERTER → SIZE BATTERY → DESIGN PROTECTION → INSTALL → COMMISSION → MONITOR
The PV array should be sized according to the amount of solar energy the business wants to generate.
The inverter should be sized according to the electrical power the business needs to operate.
The battery should be sized according to the amount of stored energy required and the purpose of that storage.
These three components are related, but they are not interchangeable.
A business with high daytime consumption may benefit from a large PV array and relatively modest battery storage.
A business with substantial nighttime loads may require more battery capacity.
A business that needs reliable backup for critical systems may use a smaller dedicated backup circuit rather than attempting to back up every machine.
A factory with motors, compressors and three-phase machinery requires a more detailed electrical assessment than a small office.
A hotel may need to combine photovoltaic electricity, battery storage, solar water heating and energy-efficiency measures.
A farm may combine solar electricity with borehole pumping and irrigation.
A warehouse may have significant roof space for a large PV array.
The best system is therefore determined by the business's actual operating pattern.
Before purchasing equipment, the business should establish its electricity consumption, peak demand, operating hours, critical loads, roof conditions, available solar area and future expansion plans.
A properly sized system can help reduce grid electricity consumption, provide backup power, improve energy resilience and support long-term business operations.
For commercial solar assessment, solar system sizing, PV installation, hybrid inverters, battery storage, three-phase solar, solar water pumping and complete business solar solutions in Kenya, contact 0723763173.