How to calculate the sizing of solar panels for home

If you’re planning to install solar panels on your rooftop in Telangana or Andhra Pradesh, one of the most important steps is getting the sizing right.

Why does sizing matter? Because the right-sized system means more savings, higher efficiency, and better performance for decades to come. Whether you live in Hyderabad, Warangal, Vijayawada, or Visakhapatnam, proper solar panel sizing ensures your investment pays off.

Here’s a simplified 6-step guide to help you understand and assess the right size of solar panels for your home.

1. Choosing the Right PV Module

The PV module (or solar panel) is the heart of your solar system. The selection process depends on a few important factors:

1. Technology: You’ll generally choose between monocrystalline and polycrystalline panels.
2. Efficiency:
   1. Mono panels offer higher efficiency (around 19–20%) and are ideal for rooftops with limited space or partial shade.
   2. Poly panels are more affordable but slightly less efficient (around 16–17%).
   3. Cost: Poly panels are cheaper upfront, but mono panels can give better output per square meter.
3. Availability: Even though many panels are assembled in India, key components like PV cells often come from China. Choose brands with reliable local supply chains.
4. Warranty & Support: Look for panels that come with 25+ years of performance warranty and strong after-sales service across AP and Telangana.

At Unilux Solar, we guide homeowners to pick modules best suited to their energy needs, space, and budget.

2. Calculating the Number of Panels

Once you’ve selected your module type, it’s time to figure out how many panels you need. Use this simple formula:

Number of panels = Total system size (in watts) ÷ Wattage of one panel

Example:

For a 10 kW system using 350 Wp panels:
10,000 W ÷ 350 W = 28.57
Round it up—you’ll need 29 solar panels.

This step helps ensure you don’t over- or under-size your system.

3. Selecting the Right Inverter

After finalizing the modules, your next big decision is choosing the inverter, which converts DC power from the panels to usable AC power.

Inverters come in two main types:

1. String Inverters: Ideal for most homes. Cost-effective and widely used in Telangana & AP.
2. Micro-Inverters: More expensive, but offer better performance in areas with shading or complex rooftop layouts.

As with panels, look for:

1. Good efficiency ratings
2. Strong warranty support (typically 5–10 years)
3. Compatibility with your chosen modules

Unilux Soar helps homeowners match their inverter perfectly with their panel setup.

4. How to Calculate the Number of Inverters

This is just like panel calculation. Here’s the formula:

Number of inverters = Total system size (in watts) ÷ Inverter capacity (in watts)

Example:

Using 2,500 W inverters for a 10 kW system:
10,000 W ÷ 2,500 W = 4 inverters

Now, to distribute the modules across inverters:

Modules per inverter = Total modules ÷ Number of inverters

29 ÷ 4 = ~7–8 panels per inverter

Note: This is a rough guide. Actual installations may vary depending on panel layout and inverter specs.

5. Calculating String Size

1. Each inverter connects to a “string” of panels. To properly design the strings, you’ll need:
   1. Voc (Open-circuit voltage) of the panel
   2. Vmp (Voltage at max power)
   3. MPPT range of the inverter
   4. Vmax tolerance of the inverter
2. Though most of this is calculated using simulation software, understanding the basics helps you ask the right questions and ensure a safe, efficient design.

6. Choosing the Mounting Structure

Your mounting structure holds the panels in place—and it’s not one-size-fits-all.

Here’s what affects the choice:

1. Type of roof: RCC, metal, slope, or flat.
2. Wind load: Especially important in coastal Andhra towns like Kakinada and Nellore.
3. Tilt angle: Your panels should face south at a tilt of around 15–25 degrees for optimal generation in Telangana and Andhra.
4. Material: GI (galvanized iron) and aluminium are commonly used.
5. Environment: Coastal areas need anti-corrosive materials.
6. Types of mounting: Choose from fixed tilt, flush mount, east-west racking, or ballasted systems depending on your roof and space.

Unilux Solar conducts site assessments across both states to recommend the ideal structure.

Bonus Step: Simulation & Shadow Analysis

Before installation, professional solar engineers run a solar simulation using design software. This step ensures:

1. Minimal shadow impact (from trees, water tanks, etc.)
2. Accurate year-round energy prediction
3. Optimal string configuration

In dense urban areas like Hyderabad or Guntur, this step is critical to avoid generation losses due to partial shading.

Conclusion

Designing a solar system isn’t guesswork—it’s a precise science. With this 6-step solar sizing guide, you now understand the key factors involved in getting your rooftop solar system right.

When installed properly, solar can power your home efficiently, reduce your dependency on the grid, and cut your bills by 80–90%—especially with the strong sunshine Telangana and Andhra Pradesh receive year-round.

At Unilux Solar, we specialize in region-specific solar design and offer free home assessments to help you size your system perfectly.

FAQs: Solar Panel Sizing in Telangana & Andhra Pradesh

Q1. How do solar panels work?

A: Solar panels absorb sunlight (usually between 9 AM to 4 PM) and generate DC power. This power is sent to the inverter, which converts it into AC electricity that runs your appliances. Extra power goes to the grid (if it’s an on-grid system).

Q2. How do I decide between mono and poly panels?

A: Mono panels: Higher efficiency (19–20%), better for smaller rooftops or low-shade areas.

• Poly panels: Lower cost, decent efficiency (16–17%), ideal if you have ample shadow-free space.

Q3. How are modules distributed among inverters?

A: Simple division:

Number of modules ÷ Number of inverters

E.g., 29 panels ÷ 4 inverters = ~7–8 panels per inverter. Actual layout may change during installation.

Q4. What’s the maintenance cost of solar panels?

A: Very low. If you choose Tier-1 panels from brands recommended by Unilux Solar, you’ll get 25+ years of performance with minimal upkeep. AMC (Annual Maintenance Contracts) usually cover basic

cleaning and checks.

Q5. Is my roof suitable for solar panels?

A: Most RCC, flat, and metal roofs are suitable. Asbestos roofs are not ideal. Our team offers free site evaluations in all major cities and towns across Telangana and Andhra Pradesh.