The architecture
A 100W panel and 30Ah LFP battery power an always-on sensor/gateway. Multiple temperature probes monitor air and pipe surface; a water sensor sits at the floor. Optional 12V heat tape can be added only as a short emergency branch after insulation has done the real work.
Load and sizing math
Sensors are tiny loads. Even a 30W heat cable used for hours can dominate them, which is why insulation and alerts come first.
| Load | Watts | Hours/day | Daily Wh | Notes |
|---|---|---|---|---|
| Cellular/LoRa monitor | 3 | 24 | 72 | Always on |
| Sensors | 1 | 24 | 24 | Temp + leak |
| Service LED | 10 | 0.5 | 5 | Occasional |
| Emergency heat cable | 30 | 2 | 60 | Optional limited duty |
| Illustrative total | 161 Wh/day | Before system margin | ||
Without heat, the system is under 110Wh/day. A 30Ah battery is ample. Emergency heat can quickly double the budget and should not be mistaken for full building heating.
Full parts list
This is a shopping architecture, not a demand that you buy one exact brand. Match voltage, current and connectors before ordering. Budget ranges reflect the class of hardware rather than a live quote.
100W solar panel
Target spec: Rigid panel
Generous for monitoring loads.
Budget: $55–$120 each
30Ah LiFePO4 battery
Target spec: Low-temp protected
Several-day reserve.
Budget: $65–$140 each
10A controller
Target spec: Load output + LFP
Keeps monitor alive without battery abuse.
Budget: $25–$80 each
Cellular/LoRa temperature monitor
Target spec: Multiple probes, alert rules
Sends warning before freezing or overheating.
Budget: $50–$200 each
Leak sensor
Target spec: 12V/USB or dry-contact
Catches pump/plumbing leaks.
Budget: $15–$60 each
12V service light
Target spec: Low-watt weatherproof LED
Makes repairs possible without flashlight-in-mouth mode.
Budget: $15–$40 each
Wiring map
Put sensing on the always-on branch; service light and any emergency heat on separate switched/fused branches.
[100W PV]-->[CTRL]-->[30Ah LFP]-->[FUSE BLOCK]
| | |
Monitor Leak Service LED
|
Temp probes
optional emergency heat branch
Step-by-step build
Insulate the building first
Seal drafts, insulate pipes and address standing water before adding electronics.
Place temperature probes strategically
Use one for ambient, one at the most exposed pipe and one near any heater/pressure equipment.
Mount panel and enclosure
Keep battery/controller dry and accessible without obstructing plumbing service.
Wire monitoring branch
Give the gateway its own low-current fuse and verify cellular/LoRa signal.
Install leak sensor low
Put sensing where water will collect first, not on a high shelf.
Add service light
Place switch inside the door and keep wiring low voltage.
Configure alerts
Set early warning above freezing so you have time to act.
Test failure modes
Chill a probe, wet the leak sensor and disconnect PV to confirm alerts and battery autonomy.
Commission it before you trust it
The project is not finished when the LED comes on. Run it through a controlled test so the first real failure is not in the field.
- Well house insulated
- Remote signal verified
- Freeze threshold tested
- Leak alert tested
- Battery charge profile correct
- Service light fused
- Panel clear of pump-service path
- Emergency contact configured
- Battery-only overnight test passed
Mistakes to avoid
Undersizing the battery because the panel is large
Panels make energy only when conditions cooperate. The battery has to carry the load through night, cloud and short high-demand events. Size energy storage from watt-hours, not panel watts.
Ignoring standby loads
Controllers, routers, cameras, inverters and cellular hardware can consume power 24/7. On small projects, a 5W always-on device is 120Wh per day—sometimes more than the 'main' load.
Using one fuse for the entire project
Fuse each branch according to its conductor and load. The fuse protects wire, not the gadget. A downstream short should not require an oversized main fuse to clear.
Mounting the panel where the project is instead of where the sun is
The load can sit in shade. The panel cannot. Use a cable run, pole or remote mount to put the collector in the best solar window.
Skipping a low-voltage disconnect
Deep-discharge protection is cheap insurance. Many charge controllers or smart battery systems can disconnect noncritical loads before the battery is abused.
Upgrade path
Add a pipe heater carefully
Use thermostat-controlled low-watt heat only after calculating winter energy and battery temperature limits.
Add pressure monitoring
A pressure transducer can detect pump cycling or plumbing failures remotely.
Add door sensor
Know when someone accesses the well house.
Frequently asked questions
Can this keep pipes from freezing?
The base build monitors and alerts; it is not sized to heat the whole building.
Why not use a 1,500W heater?
That load is far beyond a small remote solar system and would require a completely different power architecture.
Is cellular worth it?
At a truly remote property, yes; otherwise LoRa/Wi‑Fi can reduce ongoing cost and power.
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