Guide · Equipment
Keeping the power on during outages
The scene is familiar: ONEE cuts power in the middle of the day, the sun is beating down on the roof, and yet everything goes dark at your place just like the neighbours'. Many homeowners discover at that moment that their panels are useless during an outage. This guide explains why, and what needs adding — a hybrid inverter, a battery, EPS outputs — so the next outage doesn't leave you in the dark.
Sun overhead, house dark: what's going on?
A standard on-grid inverter is designed to inject electricity in phase with the grid. As soon as the grid disappears, it shuts down automatically. This legal safety requirement is called anti-islanding: the inverter must never keep producing on a line declared de-energised, at the risk of endangering technicians working on it. That's why your panels stop with the grid, even in full sunshine. To keep the power on during an outage, you need a hybrid inverter with a dedicated backup output.
Keeping the power on isn't the same as going off-grid
Many people think "riding out an outage" means doing without the grid entirely, like an off-grid system powering the whole house indefinitely. That's not what a hybrid inverter's backup mode does. It creates a limited electrical island: only the circuits wired to the EPS outputs (Emergency Power Supply) stay powered, and only as long as the battery holds energy. The goal isn't to replace the grid, but to keep the fridge, essential lights or the Wi-Fi router alive for the duration of the interruption. This nuance changes everything when sizing the installation.
EPS outputs: the hybrid inverter's backup circuits
A hybrid inverter has two types of outputs: normal grid outputs, and EPS outputs reserved for backup. During installation, an electrician wires only the priority circuits onto these EPS outputs — backup lighting, fridge, internet box, possibly a pump or water heater depending on battery capacity. The rest of the house follows the grid and shuts down normally during the outage. This separation is deliberate: it protects the inverter from overloads and lets the battery last longer on genuinely essential uses.
Deye SG series: near-instant switchover, no extra box
Deye's SG-series inverters (single-phase SG03LP1, three-phase SG04LP3) integrate backup mode natively, with no external box. When the grid goes down, the switchover to the EPS outputs is near-instant (~4–10 ms, UPS-type). This delay is so short that most sensitive electronics don't notice it, provided they're plugged into the EPS circuits. The battery used is low-voltage 48 V LFP, and the inverter offers six configurable TOU (Time of Use) windows to charge the battery during off-peak hours and maximise the autonomy available at night or during a prolonged outage.
This UPS-mode (uninterruptible power supply) operation is one of the main strengths of this range in the Moroccan context, where micro-outages and load shedding can damage electronic equipment or interrupt sensitive processes.
Huawei SUN2000 + Backup Box: a separate box to plan for
The Huawei SUN2000 range (L1 single-phase, M1 three-phase) paired with LUNA2000 batteries offers excellent integration and advanced real-time production monitoring. For the backup function, Huawei requires a separate unit: the Backup Box. Once installed, it takes over the backup circuits with a very fast switchover, fast enough for most household uses (lights, standby devices, fridge). The real difference from Deye isn't speed but the fact that an extra box is needed.
One point to check when choosing: depending on model and firmware, the three-phase SUN2000 M0 may not offer a backup function. If power continuity matters to you, confirm the backup compatibility of the exact reference, or lean towards the M1 or another range.
Hybrid without a battery: "battery-ready"
It's entirely possible to install a hybrid inverter without a battery at first. This is called a battery-ready configuration. The inverter then works like a standard on-grid system: it produces, self-consumes, and, where Law 82-21 allows it, injects a surplus onto the grid. The difference is that it's sized to accept batteries later, without rewiring everything. However, without a battery, there's no EPS backup possible: the backup outputs have no energy to distribute if the grid goes down. Backup only becomes operational once a battery is connected.
What determines backup duration: the battery
The EPS switchover only lasts as long as the battery allows. For essential uses (LED lighting, fridge, internet box), a battery of 5 to 10 kWh can cover several hours to a full night depending on the actual consumption of the connected circuits. If the panels produce during the outage (a daytime outage), the hybrid inverter can recharge the battery in real time and extend backup almost indefinitely as long as the sun is shining. This is where the hybrid system shows its full value compared to a simple generator.