What We're Building, IP67 MPPT Solar Charger for Marine and Dock Installations
There is no IP67-sealed, Bluetooth-equipped, display-equipped MPPT solar charge controller under $450 NZD on the NZ market. Building one. Here's where we are.
This post is the sixth in a series that started five weeks ago with a question: why does every marine solar controller fail in an exposed position in the same way? That question led to a competitive analysis, a field failure review (50+ forum threads and documented cases), a feature demand assessment, and a product specification. Everything that follows is derived from that evidence, not from speculation about what might be useful.
The Gap the Research Found
Competitor analysis across the NZ mid-market MPPT controller space (Victron, EPEVER, Morningstar, Blue Sky, Genasun, Mastervolt, Midnite Solar) confirmed a single consistent gap: no product below $420 USD ships with all four of the following simultaneously:
- IP67 sealed housing, not IP43 (Victron SmartSolar), not IP65 with compromised cable glands (EPEVER TracerBP), but a genuinely dust-tight, immersion-rated enclosure end-to-end.
- Bluetooth monitoring, specifically dual-mode (SPP + BLE), not BLE-only which breaks after Android OS updates.
- Ethernet Modbus TCP built in, not via a $250 gateway add-on.
- Fanless design, because a fan housing requires a vent, and a vent is an ingress path for salt aerosol.
These four features are each independently demanded by marine solar installers and marina operators in documented forum discussions. Together they constitute a product that does not exist in the NZ market at the target price point.
What We're Building
MicroCore Marine Solar Charger, MCS-SPEC-001, 2 products
- IP rating: IP67 end-to-end. TE Connectivity sealed enclosure, M12 A-coded connectors on all external connections, Gore ePTFE pressure-equalisation vent (manages internal condensation without creating an ingress path).
- Power: 250W MPPT, 20A charge current. 12V/24Vauto-detect. Buck topology, synchronous rectification.
- Cooling: Fanless, passive conduction via aluminium heatsink. No vent, no fan housing, no ingress path.
- Bluetooth: CC2564MODA dual-mode (SPP + BLE). SPP transport is independent of Android OS version.
- Ethernet: LAN8742A PHY, onboard discrete magnetics, Modbus TCP server on port 502. M12 sealed connector. One cable to the dock LAN, no gateway required.
- Battery temperature sensor: External Tb terminal (TDK EPCOS 10kΩ NTC). Automatic charge voltage compensation per chemistry. Prevents the FLA overcharging failure documented in multiple Victron installations without temperature sensing.
- Data logging: 4Mbit NOR Flash, 1-minute resolution, ~7 months retention. Circular buffer. Local data, no cloud dependency.
- Charge profiles: FLA, AGM, Gel, LiFePO₄. Configurable via Bluetooth app.
- MCU: STM32F407IGH7. Production firmware from an existing proven base, not starting from scratch.
The Evidence Behind Each Decision
Every specification item traces to a documented failure or confirmed buyer demand:
| Spec decision | Evidence |
|---|---|
| IP67 (not IP43) | Aftermarket enclosure workaround documented in 3 independent sources; IP43 allows salt aerosol ingress; 12–24 month corrosion timeline per Kim et al. (2023) |
| Fanless | IP67 requires sealed enclosure; fan housing is primary ingress path; documented in NorComp marine IP guidance |
| M12 sealed connectors | "Connectors and cable assemblies must also meet the required IP rating", NorComp marine electronics IP guidance; EPEVER cable gland failure documented |
| Dual-mode BT (SPP + BLE) | Victron BLE-only failure: 5 independent forum threads, Android 13 trigger, affected models 75/15, 100/20, 100/30 |
| Native Modbus TCP | Victron gateway cost ($250 Cerbo GX) documented; Modbus complexity documented in 3 independent integration sources |
| Battery temperature sensor (Tb) | Victron FLA overcharging incidents documented, thermal runaway at 50–54°C in parallel battery banks without Tb |
| No load output terminal | EPEVER TracerBP load terminal cycling failure under oversized arrays, documented failure mode, avoided by design |
| Gore ePTFE pressure vent | Manages condensation from thermal cycling in sealed enclosure, competitors document no equivalent |
Where We Are
Hardware design is in progress. The specification is at Rev 0.9, locked on architecture, in detailed BOM and layout phase.
What I'm looking for at this stage:
- NZ marina operators who have dock infrastructure running on solar and are currently dealing with monitoring or reliability problems.
- NZ marine electricians who've had to solve the exposed-position problem on a vessel or dock install.
- Commercial fishing operators who've had a controller fail at sea.
This is not a sales conversation. Hardware is in early design phase and pre-orders are not open yet. What I need are conversations with people who have the problem, to confirm the spec is right before the first PCB order.
If that's you: jonathan@microcoresystems.co.nz