Emit Solar | Home Solar Panels | Easy Ownership
“Save RM450 a month. Payback in six years. After that, it’s all profit.”
It sounds fantastic. But the real question is – how did they get to that number? Behind every solar savings estimate is a stack of assumptions. Some are realistic. Some are quietly optimistic. Some make the quote look better than it should. Here’s what to check before your trust the numbers.
- What PSH did they use?
Every solar company in Malaysia uses something called Peak Sun Hour, or PSH. The formula is simple: System size x PSH x days = estimated generation.
Example:
How generation is calculated
Fig. 1 The PSH Formula every solar company in Malaysia uses to project monthly generation
But here’s where quotes can get aggressive.
A quote using 3.8 PSH will look much better than one using 3.2 PSH even if the system is exactly the same. That single assumption can make a quote look 15–20% better than another for the same hardware on the same roof.
In practice, we’ve seen Malaysian companies use anywhere from 3.3 to 3.8 PSH:
Some homes do crack 4+ PSH, but that’s rare, not the norm. In Malaysia, a realistic long-term assumption is usually around 3.4–3.5 PSH. Anything much higher should come with a clear explanation.
This is based on panel sizing,— not inverter sizing. Plenty of people will show you reports from various websites quoting figures like 5 PSH (peak sun hours), but those are based on inverter sizing.
Ask Your Installer
“What PSH did you use to estimate my generation?”
One technical detail worth checking
For your panels to actually deliver their rated output, the inverter has to be sized correctly. The general rule: the inverter should be sized at around 80% of your total panel capacity but this also depends on other factors like shading, roof tilt etc.
That sounds backwards – why under-size? Because the “rated kWp” of a solar panel is achieved in lab conditions that almost never happen on a hot Malaysian roof. Oversizing the panels relative to the inverter (called “DC overbuild”) gives you a flatter, more useful generation curve through the day, without losing peak output.
If a quote pairs 10kWp of panels with a 10kWp inverter, ask why. It’s not always wrong, but it’s worth a question.
2. How Much Solar Will You Use Directly
This is the biggest driver of savings.
Solar only generates while the sun is up.
Every kWh you can use while it’s being generated saves you the full retail rate because it reduces how much electricity you need to buy from TNB. Anything left over gets exported to the grid at a lower rate.
So two homes with the same system can see very different savings. Why?
Because one uses more solar during the day, while the other exports more. Based on the homes we’ve analysed, day-time usage typically falls between 20% and 40% of total consumption.
A reasonable rule of thumb based on your bill size:
- Bill around RM300 → roughly 25% day-time usage
- Bill around RM500 → roughly 30% day-time usage
- Bill above RM750 → 35% or higher
The pattern makes sense. Bigger bills usually mean bigger homes, more aircond units, and people actually around during the day. If someone’s home full-time, or you charge an EV during daylight, your day-time share goes up significantly – and so does your solar value.
Ask Your Installer
“What daytime usage percentage did you assume?”
3. Are they using the right tariff tier?
Under the new tariff structure (from 1 July 2025), what you pay per kWh depends on whether your monthly usage crosses 1,500 kWh. Here’s how the value of every solar kWh changes based on whether you use it directly or export it to the grid:
Every kWh is worth more when used directly.
Fig 2. Under the post-July 2025 tariff, direct use is worth ~60% more per kWh than exported solar
In plain terms, what this means for solar:
- Lower-usage homes save less per kWh
- Higher-usage homes save more per kWh
That means a high-bill household can get a faster payback from the same system.
If you signed up under NEM 3.0 before it closed in June 2025, you continue to enjoy the 1:1 offset. New installations from January 2026 onwards fall under Solar ATAP – different maths entirely.
Ask Your Installer
“Which tariff tier did you use in the savings estimate?”
4. Did they adjust for EEI? (the one most quotes ignore)
This one’s tricky, but important because EEI can quietly affect your solar savings estimate.
The Energy Efficiency Incentive (EEI) is a rebate for households using 1,000kWh or less per month. The lower your consumption, the higher the rebate per kWh – up to 25 sen/kWh at very low usage levels.
It’s great, but here’s how it works with solar.
Export credits reduce your bill, but they don’t also earn EEI.
So the true value of each exported kWh may be lower than the headline export rate.
For example, say you import 1,000kWh from TNB and receive an EEI discount of 0.5sen/kWh.
If your Solar ATAP export rate is 27sen/kWh, the effective saving on the exported portion may be closer to:
27sen – 0.5sen EEI = 26.5sen/kWh
So if a quote simply adds export credits on top of your existing EEI discount, the savings may look inflated.
A proper estimate should adjust for the affected EEI portion, so the same kWh is not being “counted twice”.
Ask Your Installer
“Did you adjust the post-solar bill calculation for EEI?”
If they look confused, the answer is no.
5. SST and KWTBB
These don’t get much airtime in most solar quotes, but they add up:
- SST (Service Tax) – 8% on electricity usage above 600kWh/month
- KWTBB / RE Fund – 1.6% on usage above 300kWh/month
Both are calculated on whatever you import from TNB.
Solar Electricity that you use directly never shows up on your bill, so you save SST and KWTBB on those units too.
But for solar that gets exported and credited back later, the maths is messier – you effectively pay these charges on the full import and only get an Energy charge credit back, which means you lose the SST/KWTBB savings on the exported portion.
This is yet another reason direct self-consumption is worth a lot more than export.
Ask Your Installer
“Do your savings estimates account for SST and KWTBB effects?”
6. What Tariff Escalation Did They Assume?
Long-term solar savings depend on future electricity prices. If tariffs rise, solar savings improve. If tariffs stay flat, payback is slower.
Some quotes assume aggressive tariff increases to make long-term savings look better.
A flat assumption may be too conservative, while a very high escalation may be too optimistic.
So when you see a 20-year savings projection, take it with a pinch of salt.
Ask Your Installer
“What annual tariff increase did you assume?”
Two households – same sytem, different outcomes
To bring it all together, let’s look at two real-world scenarios. Both install the same 10kWp system, on a roof getting 3.5 PSH average.
SAME SYSTEM VERY DIFFERENT SAVINGS
Both install identical 10kWp systems on roofs averaging 3.5 PSH
HOUSEHOLD A
High-usage family
Pre-solar bill
RM800
Monthly usage
~1,700 kWh
Day-time usage
~35%
Direct use savings
RM321
Export credits
RM168
Est. monthly savings
~RM490
HOUSEHOLD B
Smaller, mostly empty by day
Pre-solar bill
RM350
Monthly usage
~750 kWh
Day-time usage
~20%
Direct use savings
RM66
Export credits
RM243*
Est. monthly savings
~RM300
*In practise, capped by actual import volumes and EEI dynamics ~ often less
Same panels. Same generation. Same roof. Wildly different savings. Day-time usage and tariff tier swing the result dramatically – which is why a generic estimate based on “average Malaysian home” can be misleading for your home.
Six questions · Before you sign
If you’re evaluating a solar quote, these are the questions worth pressing your installer on:
- What PSH did you assume?
Anything above 3.5 deserves an explanation.
2. What the inverter-to-panel ratio?
Should be around 0.8 for optimal output.
3. What day-time usage percentage (%) did you use?
Does it match how your household actually lives?
4. Did you adjust for EEi in the post-solar bill?
A telling question – most quotes don’t.
5. Solar ATAP rates or NEM 1:1 offset
For new installs in 2026+, it has to be Solar ATAP.
6. What tariff escalation did you project?
Flat is dishonest, +5% per year is ggressive, In between, resonable.
Fig 3. The shortlist worth bringing to every solar consultation
Knowing how the savings number was built is the first step to knowing whether to trust it.
Ask the right questions, run the numbers yourself if you can, and don’t be afraid to push back.
A good solar company will welcome the conversation. A great one will have started it themselves.
The Bottom Line
- Solar is still a strong investment for most Malaysian households – especially if you're on the high tariff tier, have meaningful day-time usage, and plan to stay in the home long enough to enjoy the payback.
- But the gap between an honest estimate and a sales-friendly one is real.
- Knowing how the savings number was built is the first step to knowing whether to trust it.
- Ask the right questions, run the numbers yourself if you can, and don't be afraid to push back.
- A good solar company will welcome the conversation. A great one will have started it themselves.
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