Frequently Asked Questions

We’ve shared some of our most frequently asked questions to help you out! Can’t find the answer you’re looking for?

What are the various components required for a rooftop solar system?

a. Solar PV Modules (panels)
b. Inverters
c. Aluminum alloy mounting structure
d. Batteries
e. Charge Controllers
f. AC, DC Cables, Junction Box

How much space is required to install a solar system?

About 6sqm area is required to set up 1 kWp grid connected rooftop solar system. A
3kWp installation will need 18sqm and a 5kWp installation requires 30sqm.

What is the ideal roof angle/tilt and the direction prescribed for the Philippines?

Between 10-15 degrees tilt is recommended. A South-facing slope is ideal while a North-
facing slope results to losses in yield.


A good project always starts with a good plan.

Here are some questions that you may have in mind with regards to the planning and design phase of having a solar energy solution.

How long will a solar system last?

Studies have proven that solar panels can last anywhere between 25-30 years or sometimes more. However, even past these years, they will still keep producing electricity. Meanwhile, depending on the type, make or model a solar inverter can last between 10-15 years as they have electronic parts that are sensitive to heat. Some inverters were observed to have lasted beyond 18 years.

What is the weight of the solar panels?

The weight of solar panels varies depending upon the rating. It ranges from 4.5 kg -25 kg per module.

What if my roofing is old and rusty?

Since panels have a productive life that goes beyond 30 years, you may want to have your roof checked by an expert to ensure they will last as long as the panels. Otherwise, it is prudent to have your roof upgraded in order to avoid re-installation costs in the future.

Can the installation cause damage to the roof?

No, it causes no damage to the roof. Roof mounting systems are designed to safeguard the integrity of the roof. Meanwhile, rooftop systems are very durable, and have an average lifetime of 25 years. During this period, if roof work ever has to be done, the rooftop system can be easily dismantled and reassembled. So, future roof work is always possible.

However, it is prudent to work with well-trained and reputable installers to make sure they use the right materials, tools and methods.  

Will a strong typhoon peel the panels off the roof?

No. The solar panel mounting is screwed to the roof purlins and not on the tin roof.  If the roof structure is built compliant to the country’ building construction code then these are built to withstand typhoons. In addition, mounting structures in typhoon belts are reinforced to provide added buffer against the winds.  Again, professional installers consider these conditions in the solar system design specifications.

Is battery compulsory for a solar solution?

No. A Grid-Tied Solar System with Net Metering is the most cost-effective solar solution in the market. In locations where a stable grid is available, adding batteries will only make the solar system more costly, and the cost of energy generated can be higher than that supplied by the utility.

However, in off-grid sites where grid connection is unavailable, batteries are a critical component especially when the aim is to provide stable and reliable energy supply throughout the day and into the night. In these off-grid sites homes, businesses and communities normally rely on a diesel generator for their energy supply. At the current price levels of battery storage compared against the cost of diesel fuel, energy generated by a solar PV system with battery storage proves less costly than operating a generator 24 hours a day.

Another scenario where batteries is sensible is when energy supply from the grid is  unstable and punctuated by long brownouts.  The cost of power disruption and the opportunity costs associated with it need to be calculated against the added costs of battery storage.

How solar energy panels work.

Here are some questions that you may have in mind with regards to the different kinds and functionalities of solar energy solutions.

How much electricity does a solar PV system generate?

As a rule of thumb, a 1 kWp solar system will generate about 4 – 4.5 kWh (units) of electricity in a day.  It can be slightly less and slightly more depending on factors such as location, the tilt/angle of the installation, the direction the roof area is facing and the ambient temperature.

What is the difference between a grid-tied system and an off-grid/hybrid system?

Grid-Tied solar PV systems are connected to the electricity grid and are installed in villages, towns and cities where the grid is available.  During the day, the electricity generated by the solar system feed the loads (electrical equipment, appliances and tools), or fed back into the grid when consumption is low.  In the evening and during inclement weather when the yield of the solar system dips, electricity is automatically provided by the grid.

Off-Grid or Hybrid Solar Systems are independent of any electricity grid and may be used to power a range of applications in remote areas. In an off-grid solar power system the appliances (or energy load) has no connection to the utility grid and often relies on a bank of batteries to store power for use at night and during periods of limited sun.

What happens during the rainy season when the skies are cloudy?

Solar Panels require light energy and not the heat energy to function. During inclement weather or when clouds pass, the energy yield drops, and then immediately goes back up when sunlight returns.

Will the solar system work when there is a brownout?

A grid-connected solar system stops operating when a brownout or grid failure occurs, ad goes back online once grid power is back.  However, solar systems with battery back-up will continue operating until the batteries have reached their maximum discharge setting.

The installation process for your solar energy project.

Here are some questions that you may have in mind with regards to the installation phase of a solar energy solution.

What are the steps involved in installation?

The following steps are involved in a rooftop installation?

  1. Site visit to understand location and the project details 
  2. Providing multiple installation options to customer 
  3. Close on final system design with customer 
  4. Deliver all installation materials at the site 
  5. Construction of rooftop solar system 
  6. Obtain required approvals from local electricity utility 
  7. System commissioning
  8. Apply for Net-Metering if desired
  9. Installation of Net Metering components
Who does the installation?

The construction of the system must be performed by experienced and trained installers under the supervision of an electrical engineer and supported by an experienced electrician. Installation processes must comply with international standards in solar PV installation and PEC standards.

How long does an installation phase take?

From the time of sales confirmation, it normally takes 3-4 weeks for the installation to start. The on-site construction phase typically takes 2-5 days for residential projects, depending on the system size, roof accessibility and roof type. Tile roofs are more tedious and will re quire at least 25% more time that tin roof installations.

Larger commercial projects can take between 30-60 days, again depending upon roof accessibility and mounting style. Ground-mounted systems take longer since the footing cement foundation have to be constructed and cured.

Are there any permissions needed for the installation to be done?

No construction permits are required for residential systems unless the system will apply for Net Metering. Commercial installations, regardless of size will require local construction permits and coordination with the local utility. Broadly, what the utility companies need to ensure is that the local grid is able to handle the additional electricity it receives from the solar system. And in order to do that, they need to look at:

  1. The project size
  2. The contracted load
  3. Current load on the local transformer
What is Net Metering? How is it done and will Cenag help with this?

Net metering is the process by which solar energy generated in excess of consumption can be seamlessly pushed into the main power grid. This is necessary for the system owner to get remunerated by the utility for energy exported to the grid.

Cenag supports the customer with preparing the paperwork and/or seeing thru the application process until interconnection.

Things you need to know for your system's operation and maintenance.

Here are some questions that you may have in mind with regards to the operation and maintenance phase of your solar energy system.

What are the Operation and Maintenance expenses?

Almost negligible. Maintenance activities include cleaning the panels with water and diluted rubbing alcohol solution 2x a year or monthly depending on exposure to dust and other pollutants.

Once a year, the installation need to be checked for loose cables and other mechanical conditions especially after a strong typhoon.

What is the warranty on the system?

Warranties vary from one manufacturer to another with ranges as follows:

    • Solar panels  
      • 10 – 12 years manufacturer’s warranty
      • 90% - 93% performance warranty of rated power output on 10th year
      • 80% - 85% of rated power output on 25th year
    • Solar inverters – 5 years manufacturer’s warranty
    • Mounting – 10 years manufacturer’s warranty 
Let's take a look at some information with regards to solar power project financing.

Here are some questions that you may have in mind with regards to the financing of a solar energy system.

What is the average cost of a grid-connected rooftop solar systems?

The average cost of grid-connected rooftop solar systems is determined by the choice of panels, inverters and the size of the system. The bigger the system, the lesser the cost per watt installed.  Larger installations for commercial and industrial facilities can be as low as USD 0.95 per watt installed.

Why are some solar systems so much cheaper than others?

Some components are cheaper than others, depending on the type, make or model of the major components i.e., solar panels, inverters, mounting system). To an untrained eye solar panels may look similar but some manufacturers offer better quality, performance and warranties than others.  It is best to work with professional and reliable technology partners who have proven track record, who value quality and performance and who take to heart the long-term interests of the customer.

Are banks providing any special loans for such projects?

Yes. Residential solar projects can be applied for financing with the Pag-ibig or Home Development Mutual Fund at very reasonable rates.  Commercial banks however have no residential solar financing facilities as yet.  Commercial and industrial systems may be applied for capital equipment financing with their commercial bank of choice.

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Head office: Unit 313 The Atrium Makati Avenue cor Paseo de Roxas Makati City 1200

Branch: 2F DBO Bldg. Mac Athur Highway, Poblacion, Urdaneta City 2428


+63 (02) 8551 3738 or +63 (075) 572 3740


+63 917 796 0329  or  +63 961 627 4024