The saving is minuscule compared to getting solar system yourself if you are capable of financing it.

They charge a certain rate for their system production. Usually this is not suitable for small homes.  If very big usage like few thousands kWh, then can consider this. But it will save you the most 10-20% of the current bill.

low risk, no up front payment, low return lo... it all depend on how much you are wiling to put up front 

Not worth it for a consumer. Many solar vendors out there offer EPP credit card payments at 0% (some with surcharge) upto 60 months which is 5 years. if you calculate the entire cost/sum paid, it is much more expensive for such rental/instalment plan. Because at the end of the day, somebody is financing the capex, and there is no free lunch in the world.

And depending on the vendor, the warranty period varies. In any case most all inverters and panels are warrantied for >5 years.

By the end of the contract period, you will be out of NEM.

Usually if a person with 250 ringgit bill invest 20k in solar, they will get back about 20k worth of solar product and 15k additional saving.  So roughly 35k in 10 years. (Don’t mind the depreciation )

But for the same person who goes for solar worth the package you mentioned, you will still have to pay Tnb and solar company about 220 a month. And your actual saving could be rm30. So if you do it for 10 years,  you will fork out 26k.

This is just very rough sketch but in short, this is the theory behind why it’s not so worth it.

And Thai is a very small system.  They don’t do small system for this kind of program if not mistaken.

Just my opinion, as there is other options so it is better to put them side by side for comparison and then decide which one is more suitable. Different people may have different preference. Base on the advantages you listed, let's compare them side by side
1. upfront payment
    Rental: No upfront payment
    Buy Over: Upfront payment or EPP with credit card up to 5 years
2. System ownership
    Rental: getting the system for free after contract (But this system not able to sell back to TnB and not support battery operation, all in all may need to upgrade or change to newer inverter with battery)
    Ownership: system is yours but NEM finished in 10 years
3. warranty
    Rental: worry free during contract period
    Ownership: Maintenance by owner but how often need maintenance, standard warranty to cover normal functionality of panel and inverter for at least 10 years
4. Green
    Rental and ownership both is green.
5. Return
    Rental: Some savings in electricity bills immediately, since there is no cost, but return maybe much lower in 10 years contract period
    Ownership: ROI starts after 5 or 6 years, depends on capacity and return is much higher compare to rental over 10 years contract period.

So all in all, it all boils down to item 1 and 5. How willing for you to put up a certain amount of money upfront or in advance for EPP years. And with that how much return you can enjoy down the 10 years contract period