Solar systems can be confusing when you are trying to decide how many solar panels you need, what inverter size to buy, how much battery storage is enough, or what charge controller matches your solar array.
SolarPriceNG calculators are built to make these decisions easier.
Instead of giving one number without explanation, our calculators use the information you enter, apply planning assumptions, and show you the equipment size that may suit your needs.
The calculators can also work together. A result from one tool can be used as a starting point for another part of your solar plan, and the system can connect suitable results to the SolarPriceNG solar price database.
These tools are planning tools, not a replacement for checking the exact manufacturer’s specifications or carrying out a professional site assessment.
What the calculators are designed to help you answer
Different solar questions need different calculations.
The SolarPriceNG calculator tools help with questions such as:
How much solar do I need?
What inverter size should I consider?
How much battery storage do I need?
How many solar panels do I need?
What charge controller size should I use?
Can my existing solar system power another appliance?
What size portable power station or solar generator should I consider?
Each calculator focuses on a particular part of the system so that you can understand the decision instead of treating the whole solar system as one number.
Solar System Calculator
The Solar Calculator is designed to give you a practical starting point for a complete solar system.
You enter the appliances you want to use, their quantity, power and expected hours of use. You can also select which appliances need battery backup.
The calculator then looks at several parts of the plan.
Daily energy use
For each appliance, the basic energy estimate comes from:
Appliance power × quantity × hours of use
The calculator adds these values to estimate your daily energy requirement.
Maximum load
It also adds the appliances that may be running together to estimate the highest normal load your system may need to handle.
Battery requirement
For appliances selected for battery backup, the calculator uses your chosen backup period.
For example, if the selected backup load is 1,000W and you ask for 5 hours of backup:
1,000W × 5 hours = 5,000Wh
The battery calculation then allows for the selected battery type and the planning assumptions used by SolarPriceNG.
The current planning allowances are:
Lithium LiFePO4: 85% usable capacity
Gel: 60% usable capacity
Tubular: 50% usable capacity
The calculator also uses an efficiency allowance when estimating the battery storage required.
Inverter requirement
The Solar Calculator uses the total load to estimate an inverter size. It applies a 20% continuous-load margin and takes the selected inverter type into account.
For a modern hybrid inverter, the planning power factor used by the calculator is 1.0.
For a traditional transformer-based inverter, it uses 0.8.
The Solar Calculator does not have the same detailed appliance-startup inputs as the standalone Inverter Calculator, so the final inverter must still be checked for motor and compressor starting loads.
Solar panel requirement
The calculator estimates the solar array from daily energy use, useful sunlight hours and normal solar-system performance losses.
The current solar planning model uses:
80% solar-system performance × controller efficiency
The controller assumption is:
MPPT: about 95%
PWM: about 70%
The selected panel wattage is then used to convert the required array into an estimated number of panels.
The calculator also uses the sunlight-hours value you enter. The default starting value is 4.5 useful sunlight hours per day.
Because sunlight differs by location and weather, this is a planning assumption rather than a guarantee.
Inverter Calculator
The Inverter Calculator focuses on whether an inverter can handle the appliances you want to run together.
It looks at two important things:
Normal running power
This is the power your appliances normally use while operating.
Starting or surge power
Some appliances need considerably more power when starting. This can happen with equipment such as motors, pumps, refrigerators, freezers and air conditioners.
The calculator therefore does not simply add the normal wattage and stop there.
It calculates your running load and startup requirement separately.
For continuous operation, it applies a 20% planning margin.
It then checks standard inverter sizes to find one that can meet both the continuous-load requirement and the estimated surge requirement.
For a modern hybrid inverter, the calculator uses a planning power factor of 1.0 and a surge multiplier of 2.
For a traditional transformer-based inverter, it uses a planning power factor of 0.8 and a surge multiplier of 3.
These are calculator assumptions, not universal specifications for every inverter on the market.
The exact inverter you choose should always be checked against its manufacturer’s continuous output, surge capability, battery voltage and other specifications.
Battery Calculator
The Battery Calculator helps estimate how much battery storage you need for the appliances you want to keep running during an outage or after sunset.
You enter the appliances, their power and the number of hours you want them to operate from the battery.
The calculator first estimates the energy required during the backup period.
For example:
Power × hours = energy
A 500W load running for 6 hours requires:
500W × 6 = 3,000Wh
The calculator then works backwards to estimate the nominal battery storage required after allowing for battery usable capacity and system efficiency.
The planning assumptions currently used are:
Lithium: 85% usable capacity and 92% planning efficiency
Gel: 60% usable capacity and 82% planning efficiency
Tubular: 50% usable capacity and 82% planning efficiency
The result is then converted into the required battery capacity at the selected system voltage.
The calculator can also provide a battery-bank configuration using reference battery sizes.
For Gel and Tubular batteries, it uses a 12V 220Ah reference battery.
For lithium, it uses a 100Ah reference module at the selected system voltage.
These are calculation references only. They are not a claim that every Nigerian battery has these specifications.
The actual battery you purchase must be checked against its manufacturer’s rated voltage, usable capacity, discharge capability, chemistry and other specifications.
Battery Runtime Calculator
The battery tool also includes a separate “How Long Will My Battery Last?” mode.
This is useful when you already have a battery and want to estimate how long it may power a particular load.
The calculator uses:
Battery storage × usable-capacity allowance × efficiency ÷ load
It also checks the total running load against the inverter or power-system output you enter.
The result is an estimate.
Real runtime can be lower because of factors such as battery age, temperature, discharge rate, inverter losses, wiring losses and changes in appliance power consumption.
Solar Panel Calculator
The Solar Panel Calculator focuses specifically on sizing a solar array.
It considers both:
Energy that must be produced during the day
and, when selected:
Battery energy that must be replaced.
For daytime appliances, it estimates:
Watts × quantity × hours
For battery recharge, the calculator allows for charging losses. Its current planning calculation uses a 90% battery charging efficiency assumption when converting the battery energy you enter into solar recharge energy.
The calculator then combines:
Daytime energy + battery recharge requirement
and accounts for:
Useful sunlight hours × solar-system performance
The solar-system performance is based on the environmental/system-loss setting and the selected controller efficiency.
The calculator also checks the daytime load separately. This means the array is not sized only from the total daily energy number. It also makes sure the recommended array has enough nominal capacity to support the daytime load under the selected planning assumptions.
Finally, it converts the required wattage into the number of panels needed based on the panel wattage you select.
For example, selecting 550W panels will produce a different panel count from selecting 450W panels for the same required array.
Charge Controller Calculator
The Charge Controller Calculator is one of the more technical tools because controller selection cannot safely be based on panel wattage alone.
The calculator can work in two ways.
Choosing a controller
You enter the solar panel quantity, panel wattage, battery voltage and controller type.
The basic array power is:
Number of panels × panel wattage
The planning array current is then estimated from:
Solar array watts ÷ battery-system voltage
The controller selection uses standard current classes and a SolarPriceNG 7% manufacturer-rating factor.
Importantly, this 7% factor does not reduce the calculated solar-array current.
Instead, the calculator uses it when checking whether a manufacturer’s controller current rating provides enough planning capacity.
Checking a controller you already own
You can also enter the controller’s rated current and rated solar power.
The calculator checks whether the panel array is within those ratings.
For MPPT controllers, advanced checks can also look at the manufacturer’s maximum PV voltage and PV current against the estimated array values.
For PWM controllers, panel-to-battery voltage matching must also be checked.
This is important because a controller can have enough advertised amps and still be unsuitable for a particular solar array.
The exact manufacturer’s PV voltage, PV current, PV power and charging-current limits remain the final check.
Can My System Power It?
The Can My System Power It? tool is designed for a different question.
Instead of designing a new system from the beginning, it helps you check whether an appliance you are thinking about adding may fit into an existing system.
It compares the new appliance with the other loads you expect to run at the same time.
This matters because an appliance may work perfectly well on its own but overload the inverter when other appliances are already running.
The tool can also provide an indicative battery-runtime check when battery information is available.
The appliance wattage shown by the calculator is a planning estimate unless you replace it with the actual rating from your appliance or manufacturer’s specification.
Power Station and Solar Generator Calculator
SolarPriceNG also includes a calculator for portable power stations and solar generators.
This tool looks at both battery energy and output power.
For a power-station size recommendation, it considers:
Daily energy requirement
Maximum running load
Estimated starting load
Required battery capacity
Recommended continuous output
Minimum surge capability
Suggested solar input
The battery capacity calculation uses a selected usable-energy factor.
The solar recommendation uses useful sunlight hours together with an 80% solar planning factor.
There is also a runtime mode for an existing power station and a separate solar-recharge check.
One important point is that a power station’s battery capacity and AC output are different things.
A station can have plenty of stored energy but still be unable to start or continuously run a high-power appliance if its inverter output is too small.
Why changing your inputs changes the result
Solar calculations are not based on one fixed number.
A system for a home using:
1,500Wh per day
is very different from a home using:
8,000Wh per day.
The same is true for battery backup.
A battery that can run a 300W load for several hours may not provide the same backup time when the load becomes 2,000W.
The calculators therefore use your actual inputs rather than assuming that every household, office or business needs the same system.
This is also why entering the correct appliance wattage is important.
Whenever possible, use the rating on the appliance label or the manufacturer’s specification instead of relying only on a preset estimate.
Why we show assumptions
Some solar calculations require assumptions.
Examples include:
- useful sunlight hours
- battery usable capacity
- inverter power factor
- controller efficiency
- solar-system losses
- starting or surge demand
SolarPriceNG shows these assumptions because we do not want to make the result look more certain than it really is.
A calculator result should help you understand the size of system you may need and what to check next.
It should not give the impression that one number is guaranteed to work in every installation.
Your calculator result is a planning estimate
SolarPriceNG calculators are designed to give you a practical starting point.
The final equipment selection can change because of the actual product you buy, installation conditions, cable sizes, panel wiring, battery characteristics, weather, appliance behaviour and manufacturer limits.
For this reason, a calculator result should be followed by an equipment check.
For example, after getting a controller result, check the controller’s actual PV voltage, PV current, PV power and charging-current ratings.
After getting an inverter result, check its actual continuous output, surge capability and battery voltage.
After getting a battery result, check the battery’s usable energy and discharge rating.
After getting a panel result, check the panel electrical characteristics and make sure the final array matches the inverter or controller limits.
How the calculators connect with SolarPriceNG prices
The calculators are connected to the SolarPriceNG price database.
This allows a calculated requirement to become the starting point for finding equipment in the database.
For example, a calculator may estimate:
550W solar panels
5kVA inverter
10kWh battery
60A charge controller
The site can then use those requirements to look for matching or suitable products in the SolarPriceNG database.
The price shown by SolarPriceNG is still a market estimate rather than a guaranteed seller price.
Prices can change because of brand, model, location, stock availability, exchange rates and other market conditions.
That is why the calculator and price database are designed to work together:
Calculate what you may need → understand the requirement → check matching equipment → compare current Nigerian market prices.
Use the calculators as a starting point, not the final installation design
The purpose of these tools is to make solar planning easier and more understandable.
They are especially useful when you are trying to compare different system sizes, understand why one result is larger than another, estimate your battery backup requirement, or get a starting point before speaking with an installer.
For a real installation, the final system should be checked against the exact equipment specifications and the actual installation conditions.
Our goal is not to replace proper solar engineering. It is to help you understand your system better before you buy or install anything.
Calculator note
SolarPriceNG calculator results are estimates for planning and educational purposes. Actual system performance and equipment suitability can differ from the calculator result. Always confirm appliance ratings, battery specifications, inverter limits, panel electrical characteristics, charge-controller ratings and other manufacturer specifications before purchasing or installing equipment.