Guide to Go Solar

With rising electricity prices in Pakistan, a significant portion of household income is often spent on energy bills. To address this, I decided to reduce our home's electricity consumption by exploring solar energy as a viable solution. The first step was to determine how much solar power we would need and whether it was a feasible option.

Estimating the Required Solar Panel Size

To estimate the size of the solar panel setup for your home, follow this structured calculation:

Analyze Your Past Energy Usage: Collect your electricity bills for the last 12 months.

Find Key Values: Determine the mean (average) and maximum monthly energy usage.

Use these figures to represent typical and peak energy consumption.

Convert to Daily Usage

Divide the monthly average and maximum values by 30 to calculate daily energy needs.

Factor in Solar Generation

On average, a 1 kW solar system generates about 4 to 4.5 kWh per day. This is the annual average, considering variations in seasons:

Summer: Up to 6 kWh/day per kW.

Winter: As low as 2 kWh/day per kW.

Divide your daily energy needs by 4 or 4.5 to estimate the required system size.

Balance Between Mean and Maximum

Select a system size that falls between the mean and maximum daily requirements.

This approach ensures sufficient electricity year-round without excessive costs.

Example Calculation

Mean Monthly Consumption: 600 kWh

Maximum Monthly Consumption: 900 kWh

Daily Mean: 600/30=20 kWh/day

Daily Maximum: 900/30=30 kWh

Required System Size: (for on grid)

20/4.5≈4.5 kW (mean)

30/4.5≈6.7 kW (maximum)

Once you know the system size requirement, next step to decide on system type.

Types of Solar Systems:

Off-Grid System: Completely independent of the electricity grid. Power is stored in batteries, making it ideal for remote areas without grid access.

On-Grid System: Directly connected to the grid, with no battery storage. Excess power can be sent to the grid, making it a cost-effective option.

Hybrid System: Combines features of both on-grid and off-grid systems. It uses batteries for backup during grid outages but comes with higher costs for batteries and inverters.

On-Grid vs. Hybrid Systems:

On-Grid System Disadvantage: If there’s no electricity from the grid, the solar system stops generating power, even during the day. This can be a significant drawback for areas with frequent power outages or load shedding.

Hybrid System Advantage: A hybrid system continues to generate electricity from the sun even during grid outages. Additionally, it provides backup power at night or during prolonged outages by using stored energy from the batteries.

Why I Chose an On-Grid System:

The main reason for opting for an on-grid system was the minimal load shedding in my area. Spending extra money on a hybrid system didn’t seem practical for the rare days of power outages. Additionally, batteries come with recurring costs due to their shorter lifespan, which I wanted to avoid. These factors made the on-grid system the most cost-effective and suitable choice for my needs.

Now you know the system type and size, so lets discuss on what things to buy:

Key Components:

Solar Panels

Solar panels are the most critical component of your solar energy system. To ensure long-term performance and peace of mind, careful selection is essential. Here’s a detailed breakdown:

Select a Tier 1 Solar Panel Brand

Choosing a Tier 1 solar panel brand is non-negotiable. These panels come from manufacturers with a proven track record of high efficiency, reliability, and stringent quality control. Tier 1 brands minimize the risk of manufacturing defects, ensuring durability and consistent performance.

Recommended Tier 1 Brands:

• Longi
• Jinko
• Canadian Solar
• JA Solar
• Others: There are a handful of additional Tier 1 brands that meet similar standards.

By opting for these brands, you ensure peace of mind with warranties, quality assurance, and optimal efficiency.

Pro Tip: There is usually some price variation in above brands that is usually because of import quantity (demand/supply reasons). These tier 1 brand usually offers similar efficiency, so one should select a Tier 1 brand panel with highest wattage and minimal per watt rate.

Choose the Right Type of Solar Panel

Modern solar panels differ significantly in terms of technology and performance. Here’s what to consider:

P-Type vs. N-Type Technology

P-Type Panels: An older technology with lower efficiency and reliability.

N-Type Panels: The superior choice, offering higher efficiency and better temperature resistance.

Recommendation: Always choose N-Type panels for better performance and longevity.

Bifacial vs. Single-Sided Panels

Single-Sided Panels: Standard panels that capture sunlight on one side only.

Bifacial Panels: Capture sunlight from both sides, significantly increasing power generation, especially when installed over reflective surfaces.

Advantages of Bifacial Panels:

• Higher energy output with only a slight cost increase.
• Enhanced efficiency when installed over reflective surfaces like white tiles or metallic sheets.

Recommendation: Choose bifacial N-Type solar panels for optimal energy generation. The minor price difference is well worth the enhanced performance.

Solar Inverters

The solar inverter is the brain of your solar energy system, converting the DC electricity generated by solar panels into AC electricity used by most household appliances. Selecting the right inverter is crucial for system efficiency, durability, and performance.

1. Select a Tier 1 Inverter Brand

Just like solar panels, always opt for an inverter from a Tier 1 brand. These brands offer reliable products backed by strong warranties and after-sales support.

Top On-Grid Inverter Brands

Some well-regarded Tier 1 brands include:

• SolarMax
• Solis
• Solex
• GrowWatt
• Other brands: Based on your region, you can search for top-performing inverter brands available locally.

Consider Local Service Availability

When deciding on an inverter, consider not only the price but also the availability of service centers in your region. Local support ensures quicker repairs and maintenance, minimizing downtime in case of any issues.

Example Scenario:

• In Lahore, Solis has a local service center, while GrowWatt services are located in Islamabad.
• While both GrowWatt and Solis are comparable in terms of pricing and reviews, Solis was the preferred choice due to its local service availability in Lahore.

Future-Proof Your Inverter Selection

When selecting an inverter, keep future scalability in mind.

Consider the DC Voltage Rating: Ensure the inverter’s DC voltage rating aligns with your current and potential future system size.

Plan for Expansion: If you plan to expand your solar setup in the future, it may be wise to invest in a slightly oversized inverter. The price difference between higher-rated inverters (e.g., 8 kW vs. 10 kW) is often minimal, offering greater flexibility later on.

Maintain a Balanced DC/AC Wattage Ratio

Ensure your system's DC/AC wattage ratio does not exceed 1.2. This ratio means the total wattage of your solar panels should not exceed 120% of the inverter’s AC rating. A balanced ratio ensures optimal performance and prevents overloading, which could reduce the inverter's lifespan.

Structure:

Before moving to the installation phase, proper planning is crucial. The roof structure plays a significant role in deciding how the solar panels will be mounted. Common options include:

Elevated Structures - Panels are raised above the roof.

L2 and L3 Roof-Mounted Structures - Panels are directly mounted onto the roof.

Once the mounting type is selected, the next step is estimating the available roof area. Based on the required system size (in kilowatts), you can calculate the number of solar panels needed. This helps determine how much space they will occupy.

For example, if your roof can fit three panels in a row, you should aim for configurations like nine or twelve panels to maintain symmetry. Avoid configurations that leave panels out of alignment, as this could compromise the structure’s stability and aesthetic appeal. A well-thought-out layout ensures strength.

Orientation:

For optimal energy production, solar panels should be oriented towards the south in Pakistan, unless there's significant shading or other constraints. This ensures maximum exposure to sunlight throughout the day.

Tilt Angle:

The tilt angle of your panels depends on your latitude. To find the best angle, search your city's latitude online. For winter, you might increase the angle to capture the lower sun, while for summer, a lower angle can help capture the direct overhead sun. Since we receive summers longer, so for year-round efficiency, you can set the tilt angle around 5-10 degrees less than your latitude.

Electrical Components:

Required components include, 

AC and DC Breaker, AC and DC SPDs, Over and under voltage protection device

Alternative: you could use DC isolator with fuses instead of DC breaker

If you are unsure of brand reliability then you may use a Fuse in series with breaker for an added safety. If your breakers are of reliable brand and as per required rating then it is not needed. 

Rating:

Main key point in selecting the electrical component is their rating and brand. For breaker ratings, you should buy a breaker with 20-30% safety margin at max. 

For example 

• if your inverters rated current is 16A then you can go for a AC breaker of 20A
• if your panel rated current is 12A then you can go for a DC breaker of 16A. But you need to keep in consideration the DC voltage as well depending on the number of panels in a string.

Brand Selection:

When choosing electrical components for your solar installation, it's essential to prioritize quality and reliability. In the local market, counterfeit breakers (such as those of popular brands like Schneider) can be found, but they often lack the necessary safety standards. For a reliable and safe setup, it's recommended to choose genuine products.

One brand that stands out in the Pakistani market is Chint, a Chinese brand known for its dependable performance and positive reviews. Unlike many others, Chint products are not prone to counterfeit issues, making them a solid choice for your system. 

For SPD you can buy of CHINT, and if that feels bit costly then GADA is also a good brand with reasonable price. 

Wiring:

1. Types of Wires Used in Solar Systems

A solar system typically uses two types of wires:

DC Wiring (From Solar Panels to Inverter)

• Use PV (Photovoltaic) Solar Cables: These are UV-resistant, weatherproof, and specifically designed for outdoor solar applications.
• Standard Size: 4mm² to 6mm² cables are commonly used, but sizing depends on distance and system size.

AC Wiring (From Inverter to Load/Utility Grid)

• Use Standard Copper Wires: For AC wiring, high-quality copper cables with proper insulation should be used.
• Wire Size: Depends on inverter output. Typically, 10mm² to 16mm² cables are used for home-scale installations.

Earthing and Protection:

Earthing pits play a crucial role in ensuring safety by providing a safe path for electrical surges or faults. For a reliable system, it's recommended to have at least two earthing pits: one for the AC side and one for the DC side. If you have a lightning arrestor, a third pit might be necessary.

For installation, place the pits at a safe distance from the solar array and electrical components. In my case, I had the pits installed at a depth of 25-30 feet in Lahore, where the soil was moist. This depth may vary depending on your location and soil type.

Regular maintenance is essential, including checking for corrosion and ensuring proper connections. Copper is commonly used for earthing due to its low resistance and durability, but other materials like galvanized steel are also suitable. Always ensure the pits reach moisture-rich layers for effective grounding.

When installing earthing pits, it's advisable to insert a small pipe alongside the earthing wire. This pipe allows you to pour water into the pit during dry seasons, helping to maintain proper earthing by ensuring the surrounding soil remains moist. This practice can enhance the performance of the earthing system, especially in hot, dry weather.

Additionally, always check the resistance of the earthing pit after installation. The resistance should be less than 5 ohms to ensure efficient grounding. Make sure to request this measurement from your installer.

If you're using two earthing pits, it's important to place them at least 10 to 12 feet apart to maintain their effectiveness and avoid interference.

Lightning Arrestor: Lightning arrestors are especially important in areas where there are no nearby tall buildings or structures that can protect your system. The purpose is to protect the solar setup from lightning strikes, particularly in open areas or spaces prone to thunderstorms. If your system is located in an open field or near large trees without any nearby tall buildings, a lightning arrestor would be necessary. However, if you’re located near tall structures, a lightning arrestor may not be needed. Generally, a lightning arrestor is recommended when the nearest high-rise building or tree is more than 30 meters away, but this can vary depending on local conditions and regulations.

Since by now you know what you need, so quick guide on where to get these things from in Lahore. 

Procurement:

• For Solar panels and inverters -> Hall Road
• For protection devices, breakers, spds, breaker boxes, cables -> brandreth road 

Installation:

Using the simplified blocks, so anyone could understand. 

During installation it is preferred to leave some space between SPD and breaker, because SPDs usually burnout so it won’t damage the breaker. 

Net metering and Billing Cycle:

For example, during the day, your solar system generates 30 units, and you consume 10, exporting 20 units to the grid. After 6 p.m., you import electricity, using 5 units during peak hours (which is at a higher rate) and 10 units during off-peak hours.

The balance works out like this:

• For the 10 units you consumed off-peak, they are directly "paid back" using your exported units from the morning.
• For the 5 units you consumed during peak hours, since the rate is higher, it gets converted into cash first (e.g., 5 units at 50 rupees per unit = 250 rupees).
• Then, they deduct the equivalent amount from your exported units, which were sold at a lower rate (e.g., 10 units at 30 rupees each = 300 rupees), leaving you with 50 rupees in credit.

This means you'd still have a credit of 50 rupees, which will remain in your account for the next billing cycle. Billing cycle is for 3 months, meaning that within 3 months they will keep your extra units as units, after 3 months they would be converted to credit (with purchasing at a lower rate)

With this knowledge you should be able to have a peace of mind even while going for a turn key solutions,