Seven years, three systems, and a CT scanner at Naggalama

Most of our long-running client relationships did not begin with an ambitious system. They began with something modest that worked, and then grew as the site grew. Naggalama Hospital is the clearest example we have.

2019: twelve kilowatts and a clinical daytime load

The first system was a 12 kWp grid-tied installation in captive-power configuration, which means it supplied only the hospital’s own use, and it was sized for the daytime clinical load and nothing more. There was no storage, because at that point the hospital was looking to bring down a bill rather than to survive an outage. The project was delivered together with Partnerschaft Gesunde Welt e.V., the German partner that has stayed involved at Naggalama ever since.

A modest system has one great advantage, because it gives everybody, us included, real operating data from the actual site instead of assumptions.

2021: backup enters the picture

Two years of that data made the next question obvious. The savings were working, but the critical wards were still exposed whenever the grid dropped. The extension added PV capacity to reach 22 kWp and put a 21 kWh supercapacitor backup layer over the critical wards.

Supercapacitor storage at that scale had not been done on a Ugandan hospital before. We chose it because supercapacitors, which store energy electrically rather than chemically, handle frequent short interruptions well and do not wear out from that kind of duty the way a battery would.

2026: a CT scanner changes the requirement

A CT scanner is a different kind of load, because its peak draw is high and arrives suddenly, and an interruption during imaging spoils the scan while the patient is already on the table. The scanner tolerates no interruption at all, and the system has to respond far faster than any person could.

The system we built for it is 50 kWp of PV with a 100 kWh battery, purpose-sized and feeding the scanner circuit rather than the whole hospital. It rides through interruptions on its own, and when an outage runs long it hands over to the generator in a controlled way, so the scanner never sees the switch.

What we take from it

The same site needed three different answers in seven years. The first system was about cost, the second about keeping the wards lit, and the third about protecting a single piece of equipment that the hospital has built a service around. Sizing a system properly means knowing which of those questions is actually being asked.