However, because of significant drop in the price of solar panels & more intense competition among local solar companies, it is getting more affordable.
As it was my friend who first ignited my interest in installing the solar panels under NEM 3.0, initially I decided to appoint the same solar company as he chose.
I got a quotation but then I felt that I should do some research on this matter before I made my decision. It's not a small investment to me.
Luckily I did that.
How much capacity to install?
The solar companies will recommend how many solar panels or how many kWp to be installed base on the average monthly electricity bill.
As my average TNB bill is RM300 per month (single phase), most solar companies recommended around 6.5kWp.
Finally I settled for a 6.4kWp solar PV system (10 solar panels), with an estimated solar electricity generation of 653kWh a month according to the solar company.
In Jul25 my solar PV system generated 768kWh of electricity, which is the highest so far. If I use the old TNB tariff to calculate, it is equivalent to RM323 of TNB bill excluding the taxes.
In average, my solar PV system generates 722kWh per month during the first 4 months (Jun25-Sep25), which is 10% better than the estimation by the solar company.
However, middle of the year should be the hottest period in a calendar year. It has been raining a lot recently and I can see the electricity generation dropping significantly in the first week of October.
Which solar panel brand should I choose?
From my experience, each solar company carries one or two solar panel brands with them, some might have more.
I just Google searched the best and most efficient solar panel brands in the world, and checked whether the brand that I was quoted was in the top 10 list.
There are other factors to consider such as whether the panel is the latest generation, whether it is bifacial and N-type, its efficiency rate, degradation rate, warranty period etc.
I didn't go into detail on all these. As long as the brand is top and the panel given is its latest version, it should be OK.
The one I chose is LONGi which I myself is not familiar with, but it seems to be a top brand worldwide.
String Inverter or Microinverters
Every solar PV system needs an inverter to convert DC electricity to AC electricity.
String inverter converts the electricity from all the solar panels at a single centralized location from DC to AC, while microinverter can be installed at each solar panel and converts DC to AC independently at panel level.
Generally microinverters are more efficient but it will cost more. Perhaps this is the most important decision we have to make while installing home solar PV system.
Certain solar companies straight away recommend string inverter without giving a chance for their customers to choose between string inverter & microinverters, probably they want to set the overall price to the lowest to attract customers.
Some companies argue that string inverter is good enough as long as there is no shade on the roof that can obstruct the sunlight.
However, after seeing the picture below, I decided to go for microinverters.
Under string inverter, if one out of 10 solar panels has its output dropped by 50%, the whole system will drop by 50%. The power production will follow the worst performing panel.
If one panel completely spoiled, then the whole system might stop working altogether until repair or replacement is done.
Microinverter will solve such issue as the DC-AC conversion will take place at the level of solar panel, and the bad performance of one panel will not affect the others.
As microinverters are more expensive, most solar companies do not recommend one microinverter to one solar panel. It's common that 3 or 4 solar panels being linked under one microinverter.
I chose microinverters mainly because it's more efficient and there is no need to hang a bulky string inverter on the wall. My 10 solar panels are connected to only 3 microinverters.
Besides, microinverters should have less technical issues and longer warranty period (>20 years) compared to string inverter (10-12 years).
After using the solar PV system for 5 months, I'm grateful that I chose microinverters because even though there is no shade on the roof, I find that the orientation of the solar panels might significantly affect the power output in string inverter negatively.
Nevertheless, there is another way to offset the problem with string inverter, which is to add power optimizers to each solar panel.
The power optimizer will optimize the performance of all solar panels in the whole system so that it won't be negatively affected by low output from one panel.
The optimizers need to be installed at every solar panels and a string inverter is still required. It generally costs lower than the microinverter but since it has to be installed in every solar panel, I'm not sure how the overall cost will be compared to microinverters just connecting to every 3-4 panels.
With the introduction of SelCo with a battery storage system, another type of inverter comes into play which is the hybrid (DC-coupled) inverter.
A hybrid inverter is something like a combination of a string inverter & battery inverter in one unit. It converts DC from solar panels into AC for household consumption, while provides DC to charge the storage battery.
For those who wish to add a battery storage to an existing solar PV system with either string inverter or microinverters, an AC-coupled storage inverter should be added to convert AC back to DC to charge the battery.
For those who wish to install new solar PV system under SelCo, may be hybrid inverter + optimizers is a good choice. I'm not sure whether microinverters + AC-coupled storage inverter is cost-effective or not.
Solar ATAP, which enables offset of excess energy exported to TNB like NEM but at fluctuating System Marginal Price, will commence in 1 Dec 2025.
Does Solar ATAP require a storage battery?
I don't know whether installing a storage battery in Solar ATAP or NEM will provide more saving. As far as I know, a storage battery is usually not enough to cover all the electricity consumed in one night.
Thus, electricity from the grid is still needed at night even with a storage battery, unless we install high capacity battery which will cost even more.
Is it cheaper to use ALL the energy generated by the solar panels and stored in the battery, or is it cheaper to export it to the grid to offset the electricity imported from the grid?
Where to place the solar panels?
The orientation of the solar panels and their angle are important to maximize the energy output.
From what I read online, since Malaysia is located north of the equator, the best direction is to face south, and the ideal angle is 10-15 degrees.
We can't change the angle of our roof but we can decide which direction for the panels to face, especially those semi-D and bungalow houses.
For a terrace house, most probably there are only 2 directions available and it is wise to split into half, or may be more facing south if feasible.
In my case, I have 3 directions available which are south, north and west.
Since I only install 10 panels, initially the contractor recommended to split into 2 groups facing north and south direction.
However, I asked them to change to facing south and west.
I think this is a good move as in my case, panels facing west consistently perform better than panels facing south! Theoretically I would assume that panels facing north will perform the worst.
I believe that most people will just follow the orientation of the solar panels proposed by the contractors. Sometimes you can have your say.
I will write another post to explain my case later.
Reliability of the solar company
It is important to engage with a reliable solar companies with good track records.
The longer warranty period given for its equipment & workmanship the better it is. However, we need to make sure the company is still around and can respond swiftly when we call them.
It's also important to consider the cost of annual scheduled maintenance and on-call service, and how long free service period is provided in the package.
I see that there are quite a lot of new solar companies being set up to share the cake of this solar business.
I don't mean that you should avoid all those young companies, as all great companies started from zero.
Initially I planned to engage with those publicly listed solar companies. However, most of them quoted higher prices and some even didn't respond to my quotation request.
Anyway, higher price does not always mean expensive. Some might give better panels, better inverters, better warranties, better add-on benefits and better reliability.
Lower price might has its reasons for being cheap too. So it's about striking a balance.
The purpose of this article is to share my experience to those who are interested in installing rooftop home solar PV system in Malaysia.
All these information might not be true or accurate.
Readers are advised to contact the person-in-charge of solar companies or contractors to get their professional advices.
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