Hybrid solar system
Grid is there but goes out: solar by day, battery by night, grid as the fallback, and the loads stay on through a brownout. The usual choice for a Philippine home that can afford the battery.
Open it in the simulator ▸Size it from my electric bill
What is in it
3,150 W of panels, a 24 V 300 Ah LiFePO4 battery (7.7 kWh), 3,600 W of inverter. 22 parts in all, wired and sized the way the lab's solar studio sizes them.
- Seven 450 W in one string, 3.15 kWp
354 V at 10 °C under the hybrid’s 450 V; Vmp 251 V hot over its 60 V minimum. - PV disconnect, DC SPD
As every array. - Hybrid inverter 3.6 kW, 24 V, solar-battery-utility
Runs the loads from solar, then battery, then grid (SBU); charges at up to 120 A; carries the loads through an outage in a few cycles. - 24 V 300 Ah LiFePO4, breaker 200 A on 4/0
7.7 kWh for a night with the aircon; the breaker is the inverter’s 161 A × 1.25, under the cable’s 260 A. - Grid breaker 32 A, AC SPD
The grid enters the hybrid’s AC-IN and never meets its output: no backfeed path. - AC breaker 20 A to the loads
The hybrid’s output is the house’s backup bus. - Ground rod
Electrode for both SPDs.
A clear day on this system
The lab ran this exact system through a clear day: 36 hours from 18:00 the evening before. The panels harvested 11 kWh and the loads used 15 kWh; the grid supplied 3.4 kWh; the battery went between 9 % and 98 %.
Parts and prices
Philippine prices as estimates (about US$2,151 in all at ₱64 per US$). In the simulator, Buy all the parts gives the same list with shop links where we have them.
| Part | Qty | Est. |
|---|---|---|
| Hybrid solar inverter 3.6 kW · 24 V battery | 1 | ₱18,000 |
| Solar panel 450 W · 144 half-cell mono | 7 | ₱56,700 |
| LiFePO4 battery LiFePO4 25.6 V 300 Ah · 7680 Wh | 1 | ₱54,150 |
| AC breaker 2-pole MCB · C20 | 1 | ₱280 |
| AC breaker 2-pole MCB · C32 | 1 | ₱280 |
| DC breaker 2-pole MCB · C16 | 1 | ₱380 |
| DC breaker 2-pole MCB · C200 | 1 | ₱380 |
| Surge protector (SPD) AC SPD, Type 2, 275 V · DIN-rail module, two pluggable varistor cartridges with a status window each | 1 | ₱650 |
| Surge protector (SPD) PV DC SPD, Type 2, 600 V · DIN-rail module, two pluggable varistor cartridges with a status window each | 1 | ₱950 |
| 220 V bulb A60 E27 · LED 54 W | 1 | ₱90 |
| 220 V desk fan 12-inch desk fan · 40 W | 1 | ₱950 |
| Household appliance Aircon 1 HP inverter · 900 W max, about 495 W once the room is cool | 1 | — |
| Household appliance LED TV 43" · 100 W | 1 | — |
| Household appliance Refrigerator · 150 W | 1 | — |
| 12 AWG (3.5 mm²) THHN any colour | 5 m | ₱240 |
| 12 AWG (3.5 mm²) THHN red | 5 m | ₱240 |
| 14 AWG (2.0 mm²) THHN any colour | 2 m | ₱70 |
| 14 AWG (2.0 mm²) THHN black | 1 m | ₱35 |
| 14 AWG (2.0 mm²) THHN red | 1 m | ₱35 |
| 4/0 AWG battery cable black | 1 m | ₱980 |
| 4/0 AWG battery cable red | 1 m | ₱980 |
| 8 AWG (8.0 mm²) THHN any colour | 1 m | ₱110 |
| 8 AWG (8.0 mm²) THHN red | 1 m | ₱110 |
| PV cable 4 mm² black | 16 m | ₱960 |
| PV cable 4 mm² red | 18 m | ₱1,080 |
| Estimated total | ₱137,650 |
What the safety check verifies
- ✓ Cold-morning Voc inside the Hybrid inverter's input
- ✓ Hot-noon Vmp stays above the controller’s minimum
- ✓ PV conductors rated for 1.56 × Isc
- ✓ Array-to-controller voltage drop
- ✓ DC disconnect between array and controller
- ✓ Hybrid inverter set for the 24 V bank
- ✓ Battery to Hybrid inverter protected: Battery breaker
- ✓ Battery disconnect: Battery breaker
- ✓ Battery-to-inverter drop
- ✓ Hybrid inverter sized for its loads
- ✓ AC breaker on the inverter output
- ✓ Surge protection on each side
- ✓ Every SPD’s PE reaches the earth
- ✓ Grounding electrode: the service ground
Questions
How big is this hybrid solar system?
As drawn: 3,150 W of panels, a 24 V 300 Ah LiFePO4 battery (7.7 kWh), 3,600 W of inverter. Every size can be changed in the simulator, and Solar & wiring → My house sizes one from your electric bill.
Does it work in a brownout?
Yes: the hybrid inverter switches to the battery when the grid fails, and keeps using the panels to charge it.
Is the wiring diagram correct?
It is drawn from the working simulation: every line is a real connection on the bench, and the safety check passes 14 checks with no fails. It is a design to learn from and adapt: check it against your local electrical code and the manuals of the parts you buy.
On the bench
Open it in the simulator ▸All solar systems and builds
Other systems
Off-grid solar system · Grid-tie solar system · Off-grid inverter + ATS (budget hybrid) · AC-coupled solar with battery · 12 V solar for an RV, boat or small DIY · Three-phase grid-tie solar