Solar Mini-Grid Design in Nigeria: 8 Steps

A mini-grid is a small power plant with its own network that serves a village or town. In Nigeria, more than 80 million people, nearly 40% of the population, lack access to electricity, says the World Bank (content dated 30 June 2024). Last updated: November 2026.

This guide shows the design steps in order, with a worked sizing example you can rerun with your own survey data. It uses the NERC Mini-Grid Regulations 2026 and the IRENA Nigeria roadmap as sources. For related reading, see adding battery storage services and the solar storage design guide.

Worked Example: Sizing a Mini-Grid for a Village

This example shows how the first steps fit together. Every input is an assumption for the example, not a measured value or a real project. The arithmetic is shown so you can swap in your own survey data.

The sun hours above are the low end of a national yearly range, not a worst-month value. Use your site’s worst month in a real design. The inverter size and the cost of energy depend on your load list and your quotes. We have not put figures for them here. The generation and financial tool can test the result with your own inputs.

Step 1: Assess the Site and the Community Demand

Start with the sun, the grid and the people. IRENA’s Nigeria roadmap (2023) says average yearly global horizontal irradiation runs from 1,600 to 2,200 kWh per square metre. The highest values, above 2,000 kWh/m2, are in the north. That is about 4.4 to 6.0 kWh/m2 per day (1,600 / 365 and 2,200 / 365). Use site data for your own design, not these national limits.

Then map the nearest grid line and the loads. Anchor loads are big, steady users such as clinics, schools, mills and telecom towers. They give steady income and shape the size of the system. Check each anchor client’s real use with meter readings or fuel logs.

Survey the households. Record each appliance, its hours of use, and what people can pay. Include shops and workshops. Plan for demand to grow after connection, and phase the build so you do not oversize on day one. Use shadow analysis to check trees and buildings, and note how fast trees will grow.

Step 2: Size the PV Array

The array must make enough energy on the worst month, not the average. Use this chain:

1. Find daily demand in kWh from your survey.
2. Add the battery losses for the energy used at night.
3. Divide by the peak sun hours of the worst month.
4. Divide by the performance ratio, the share of the ideal output that you really get after heat, dust and wiring losses.

Heat cuts output, so use the temperature coefficient on the module datasheet. Dust and rain also cut it, so add cleaning to your plan. Check the string voltage against the inverter window at the hottest and coldest site temperature. A solar design platform can run the hourly simulation with weather data.

Step 3: Size the Battery Bank

The battery carries the load through the night and through cloudy spells. Size it from the energy used at night and the days of autonomy you want. Autonomy is how long the battery can supply the load with no sun. Then divide by the allowed depth of discharge, the share of the battery you let it use each cycle, as in the worked example.

Pick the chemistry from the maker’s datasheet for cycle life, temperature range and warranty. Do not trust a general rule. Plan for ventilation, fire protection and a safe place for the battery. NERC requires a permit holder to follow battery handling, fire safety and health and safety rules that fit the project (Regulations 2026, section 19(4)).

Step 4: Select the Inverters

Choose between AC-coupled and DC-coupled designs. In an AC-coupled design, solar inverters feed an AC bus and separate battery inverters manage charging. In a DC-coupled design, solar charge controllers feed the battery, and one inverter makes the AC. AC coupling is easier to expand in steps. DC coupling has fewer conversion steps. Check each maker’s datasheet.

Size the inverter for the peak load and the motor-starting surge. Pumps and mills draw a high current when they start. Use the surge rating and its duration from the inverter datasheet. Choose inverters with open communication protocols, so you can add other brands later. See the inverter sizing entry for more.

Step 5: Design the Distribution Network

The network takes power from the plant to each meter. Plan the layout from your village map: a line along a road, or branches to clusters of compounds. Place transformers near the loads.

Check voltage drop on the longest run, using real load flow. Set the limit from the Nigerian Distribution Code. NERC says a permit holder must follow the Technical Codes (Regulations 2026, section 16). They include the Grid Code, Distribution Code, Metering Code, Health and Safety Code and NESIS Regulation. Good earthing and lightning protection protect the plant. Test the earth resistance before every rainy season.

Metering follows the Metering Code (section 20(3)). A permit holder must also publish a customer charter. It covers billing, meter failure, outages and complaints (section 20(2)). Prepaid meters and token sales can support the billing plan.

Step 6: Meet the NERC Rules and Get the Permit

The NERC Mini-Grid Regulations 2026 (Regulation NERC-R-001-2026) apply to isolated mini-grids up to 5 MW per site and interconnected mini-grids up to 10 MW per site. Source: NERC.

Other points from the Regulations:

• NERC may issue a permit within 30 business days of an application that meets all requirements (section 10(2)).
• A Distribution Licensee must answer a request for confirmation or objection within 15 business days. If it does not, it is deemed to have no objection (section 7).
• You must file the community agreement (Schedule 11 form) and the map coordinates. You must also file an end-user tariff from the mini-grid tariff model (section 7).
• For a solar or battery mini-grid up to 10 MW, NERC requires environmental screening and an Environmental and Social Management Plan (ESMP). A full environmental impact assessment is not required only because of size. It is required in places such as wetlands and flood-prone areas (section 19).
• No mini-grid may start commercial operation until you show NERC evidence of the environmental steps (section 19(5)).
• A registered operator is not bound by the Technical Codes. A permit holder is (section 16).
• Operators file an annual report for capacity below 1 MW and a quarterly report above 1 MW (section 22).

The rules came into effect on the date NERC approved them by resolution. The PDF on the NERC site is dated April 2026. See also our guide to off-grid solar design in Nigeria.

Step 7: Build the Financial Model and the Tariff

The tariff must come from the NERC mini-grid tariff model, and NERC must approve it (section 7). Build a model with capital cost, running cost, battery replacement, taxes and expected sales. Test it with low connection rates and a weak naira.

We do not give cost or return figures here. We could not source current Nigerian price data. Use your own supplier quotes and the NERC model.

Step 8: Check Common Design Failures and Plan the Handover

These faults are common, so check for them in your design review:

• Battery too small for cloudy weeks. Size from the worst-month data.
• Voltage rise on long feeders. High solar output at midday can push voltage up and trip inverters.
• Poor earthing and no surge protection. Lightning damages inverters and controllers.
• Missing documents. Keep as-built drawings, single line diagrams (SLD, a simple drawing of how the plant is wired), datasheets and a spare parts list. Train local operators.

NERC asks for milestone reports during development and construction (section 22). After commissioning, an interconnected plant needs approval from the Distribution Licensee. The licensee must give approval or its written reasons within 15 business days of the commissioning papers (section 9(18)).

To take the sizing steps into a design, see solar design software or book a SurgePV demo. SurgePV publishes this post and sells solar design software. If you are comparing tools for Nigerian projects, see our list of the best solar design tools for Nigeria.

Frequently Asked Questions

How do you design a solar mini-grid in Nigeria?

Follow eight steps: assess the site and demand, size the PV array, size the battery, select the inverters, design the distribution network, meet the NERC rules, build the financial model, and check common design failures before handover.

What size of mini-grid do the NERC rules cover?

The NERC Mini-Grid Regulations 2026 apply to isolated mini-grids up to 5 MW per site and to interconnected mini-grids up to 10 MW per site.

Do I need a permit or can I register a mini-grid in Nigeria?

An isolated mini-grid of up to 100 kW may apply for a permit or register on the Schedule 2 form. Larger isolated mini-grids need a permit. An interconnected mini-grid needs a Tripartite Agreement filed with NERC, and NERC may register it and grant the permit.

How long does NERC take to issue a mini-grid permit?

The Regulations say NERC may issue a permit within 30 business days from the date an application meets all requirements. A Distribution Licensee must answer requests within 15 business days.

What environmental papers does a Nigerian solar mini-grid need?

For a solar or battery mini-grid up to 10 MW, NERC requires environmental screening and an Environmental and Social Management Plan. A full impact assessment is needed in places such as wetlands and flood-prone areas.

How much sun does Nigeria get?

IRENA says average yearly global horizontal irradiation runs from 1,600 to 2,200 kWh per square metre, with the highest values in the north. That is about 4.4 to 6.0 kWh per square metre per day.

What reports must a mini-grid operator file with NERC?

An operator files an annual operational and commercial report for capacity below 1 MW and a quarterly report above 1 MW. It also files milestone reports during development and construction.