The bottleneck in Singapore’s EV charger rollout isn’t the chargers: it’s the switchboard

Where a legacy estate has no multi-phase backbone, work starts with a detailed electrical assessment covering expected charging demand, the incoming supply, spare switchboard capacity, cable routes, and how much energy residents actually need.

Where demand is sustained, an upgrade would make the most sense, with the new infrastructure serving the estate for years. But the right upgrade also matters. According to Lai, where spare power is tight, several intelligently managed AC chargers often beat one high-powered unit.

Dynamic load management and battery-buffered charging are two methods that can help EV charging stations prevent power overloads and operate efficiently where electrical grid capacity is limited. But even these have limitations, Lai said.  

Dynamic load management can keep a site within its agreed capacity by distributing power among connected vehicles, but it cannot create electricity capacity that does not exist. While battery-buffered charging can reduce a charger’s instantaneous demand on the building, it is more of a site-specific solution, not the default answer for every older estate.

Why the condo gets a fast charger and the HDB block does not

All too often, newer private housing estates offer fast charging while older estates offer only normal speeds. The difference often comes down to electrical capacity rather than the housing type.

Newer developments tend to have modern switchboards and spare capacity, which makes upgrades cheaper. Older buildings have limited headroom, ageing cables and awkward multi-storey routing. Supporting several fast chargers there can mean new feeders, new distribution boards and sometimes a transformer upgrade.

This is not a public-versus-private issue, as older private condominiums hit exactly the same wall as older HDB estates. A 1990s condominium with a basement car park, congested riser and a distant switchboard can be a harder job to retrofit than a 1980s surface car park with an accessible electrical room.

“Some older developments have straightforward cable routes, accessible electrical rooms and sufficient spare capacity, making them easier than newer sites with highly congested services or distant switchboards,” Lai says. What matters more is accurate electrical records, physical access, cooperation from the building’s Licensed Electrical Worker, and early agreement on which parking bays will be used.

What a good retrofit looks like

A good retrofit starts with a scalable design rather than a charger treated as an appliance. 

Most older HDB car parks were built with enough spare electrical capacity for perhaps three to twelve slow chargers at around 7kW, and no more. A single 50kW DC charger typically needs a dedicated three-phase supply in the 100 to 150-amp range or higher.

Six things have to happen, in order:

According to MNL, this could end up being a six-digit figure once the costs are calculated. These comprise:

Why faster isn’t always better

Singapore is planning for every HDB town to have at least one fast-charging hub by the end of 2027, alongside the wider residential AC network. But drivers keep asking for speed when charging, and speed is precisely what many older estates can’t support, Lai says: 

“The goal here should be to deliver sufficient energy by the time the driver needs the vehicle, rather than providing the highest possible charger rating everywhere.”

He argues that most private cars sit parked for hours when their owners are at home or work, which is an opportunity to charge gradually without needing a fast charger. For example, a resident who plugs in at 8pm and leaves at 7am may not gain meaningful convenience from a very expensive high-powered charger.

When using AC charging, the real charging speed depends on the car’s onboard charger, battery temperature, state of charge and charging curve. DC charging slows as the battery fills, and many vehicles can’t accept the full output of even a 22kW AC unit. There are concerns that frequent use of high-power fast charging can create extra heat and accelerate battery wear over time.

This means that all too often, the number printed on the charger doesn’t reflect the charging speed a car receives throughout the session.

Grid upgrades remain the biggest bottleneck

Asked to name the constraints whose removal would speed up rollout to the heartlands, Lai doesn’t hesitate to call out the time, cost and site-by-site coordination of grid upgrades and service connection work.

Both the HDB and SP Group are needed to resolve the issue. HDB can drive bulk or standardised upgrade programmes across estates, while SP Group, as the grid operator, executes the connection and transformer upgrades. 

“A coordinated, government-led programme of standardised or pre-emptive electrical capacity upgrades across older heartland estates would be the ideal intervention,” Lai added.