The defining solar water heating decision in 2026: dedicated solar thermal (Heliodyne / SunEarth) vs solar PV electricity feeding a heat pump water heater (Rheem ProTerra, AO Smith Voltex, Stiebel Accelera).
| Solar Thermal (Heliodyne) | Solar PV + Heat Pump | |
|---|---|---|
| Direct sunlight-to-water efficiency | 50-70% | ~25% (PV) × COP 3-4 (HPWH) ≈ 75-100% effective |
| Electricity also produced | No | Yes — runs other home loads |
| Federal incentive | ITC 30% | ITC 30% + IRA $2,000 HPWH credit |
| Install cost (typical) | $6,000-10,000 | $15,000-25,000 (PV) + $2,000-3,000 (HPWH) |
| Lifespan | 20-30 years (collectors) | 25-30 years (PV) / 10-15 years (HPWH) |
For most modern installs, PV + HPWH wins on flexibility (electricity is also useful for EV, HVAC, etc.). Solar thermal still wins in high-demand applications or where federal+state stacking specifically favors it.