So far we have tested Barrel OS on a single Planet. A community is a different problem: more buildings, different day and night loads, and two ways to help each other. You can move energy, with a line that links the nodes. Or you can move compute work, which travels over fibre or radio and costs almost nothing.
We chose Lampedusa because it brings together, within a few kilometres, almost everything Barrel is designed for: healthcare, public administration, security, reception, school and water. It is a minor island not connected to the national grid: electricity comes from a diesel plant.
The case
| Node | What it does | Installed compute |
|---|---|---|
| Outpatient clinic | healthcare, 24/7 service (critical) | 30 kW |
| Town hall | offices and front desk, daytime | 30 kW |
| Reception centre | translation and transcription, more in summer | 20 kW |
| Coast guard and harbour | security, 24/7 (critical) | 25 kW |
| School | daytime in school months; the rest of the time hosts deferrable jobs | 30 kW |
| Desalination plant | produces water when there is sun, with a two-day tank | 30 kW |
Each node has one JA Planet (125 kW, 261 kWh) and 250 kWp of PV: 1.5 MWp and 1.57 MWh in total. The sun is real: hourly PVGIS series for Lampedusa, year 2023 (1,656 kWh per kWp). Building loads are hypothetical profiles we built, not measurements: we declare them in the code.
Five ways to run the same island
| Scenario | Energy from the island grid in one year | Compute demand served | Water demand produced with sun |
|---|---|---|---|
| Isolated nodes, without Barrel OS | 216 MWh | 100% | 64% |
| Microgrid, without Barrel OS | 89 MWh | 100% | 92% |
| Isolated nodes with Barrel OS | 42 MWh | 78% | 94% |
| Isolated nodes with Barrel OS and migrating compute | 47 MWh | almost 100% | 94% |
| Microgrid with Barrel OS | 17 MWh | 86% | 97% |
When a node cannot manage on sun alone it draws energy from the island grid, i.e. diesel. Water the desalination plant cannot produce with sun is made by the existing plant: that energy is counted too.
What we learned
- The problem is the night, not the sun. With 1.5 MWp the island produces twice what the six nodes consume. Without an orchestrator, though, batteries empty at night and 18% of consumption comes from diesel.
- Software matters more than the line. Barrel OS alone, without linking the nodes, brings diesel from 216 to 42 MWh. The microgrid alone, without an orchestrator, stops at 89.
- Moving compute is almost worth a line. If user requests can run on another node, practically all demand is served with 47 MWh of diesel, half the microgrid without software, and without laying a metre of cable.
- Together they do more. Microgrid and Barrel OS fall to 17 MWh, less than a tenth of the starting point.
- December remains the hard month. Even with the microgrid, in the darkest week batteries hit the bottom almost every night. With a second battery cabinet per Planet (configuration to confirm with the manufacturer) the microgrid with Barrel OS falls to 11 MWh and serves 99% of demand.
- Water is a second battery. The desalination plant runs when there is sun and the tank does the rest: with the microgrid 97% of water demand is produced with sun.
- In summer the sun is ahead. About half of annual production finds no use: there is room for more compute, more water or other island services.