Solar Hybrid: grid savings with a battery for when the grid fails

Panels generate direct current exactly as they do on a plain grid-tied system. The difference is the inverter: a hybrid inverter can route that generation to your loads, to the battery, or out to the grid, and can also draw from the battery or the grid to make up a shortfall. A charge controller inside it manages the battery so it is neither overcharged nor run down further than the chemistry allows.

While the grid is up, the system behaves like an on-grid one: it offsets your consumption first and exports or stores whatever is left over, according to how it is configured. When the grid goes down, the inverter disconnects from it — the same safety requirement every grid-tied inverter follows — but instead of shutting down entirely, it switches the circuits you have wired to its backup output over to the battery.

Backup is a design decision, not a default

Not every circuit in the building goes on backup automatically. Lights, a refrigerator, a router and a few sockets are a realistic backup load for most homes; an air conditioner or a borewell pump usually is not, because carrying them through an extended outage needs a battery bank sized closer to an off-grid system’s. Deciding what stays on is part of the survey, and it is what actually sets the battery size — not the panel array.

A hybrid solar system has two sizes to settle, and they come from different places. The panel array is sized from your electricity bill, the same way an on-grid system is. The battery is sized from the circuits you want kept running during an outage and how long you want them to run.

Start by listing those circuits and what each one draws. The rating plate on an appliance, or its manual, gives its power in watts. Multiply each figure by the hours you want it to run during an outage, then add the results. That total, in watt-hours, is the energy the battery has to deliver.

As an illustration only, take a home that wants six LED lights at 10 watts, two ceiling fans at 75 watts, a refrigerator averaging 150 watts and a Wi-Fi router at 10 watts, all for four hours. That comes to 370 watts, or 1,480 watt-hours over the four hours. These are example figures; your own appliances will differ.

A battery cannot give up all of its stored energy without harm. Lead-acid batteries last longest when they are not discharged deeply, and some energy is lost converting stored direct current back into the alternating current your home uses. So the bank has to be larger than the 1,480 watt-hours the loads consume. The battery backup calculator does this arithmetic. It asks for the load you want to keep running, the hours of backup, the battery type and the system voltage, then suggests a bank size.

Bring that list to the site survey. It turns “I want backup” into a number Origian can design against, and it shows quickly whether you are describing a hybrid system or something closer to off-grid.

Panels: Renewsys, Adani, Waaree, Tata. Inverters: Growatt, Solis, Goodwe.

Luminous lead-acid batteries currently installed. Lithium (LiFePO4) batteries not yet offered, planned for the future. Battery warranty varies by brand and model, typically 3 to 5 years.

Origian currently installs Luminous lead-acid batteries in its battery-backed systems. Lithium iron phosphate (LiFePO4) batteries are not yet offered; they are planned for the future. Battery warranty varies by brand and model and is typically 3 to 5 years. That is far shorter than the cover on the panels, so the battery is the part of a hybrid solar system you should expect to replace during the system’s life.

Lead-acid is a mature, widely serviced chemistry, and it asks for a little care in return. Keep the battery bank in a shaded, ventilated spot, because heat shortens battery life and charging can release gas. If the batteries are a flooded type, the water level needs checking and topping up with distilled water at intervals. Avoid running the bank down to empty as a habit: the shallower the regular discharge, the more cycles a lead-acid battery gives.

If lithium matters to you, say so at the survey. Origian can tell you what it installs today and size the system around it, rather than promising a chemistry it does not yet supply.

A hybrid system stays connected to the grid, so it uses net metering like any grid-tied installation. The net meter records the units you import from the grid and the units you export to it, and your DISCOM settles the two under its net-metering rules.

The battery adds a choice about daytime surplus. It can charge the battery first and go to the grid second, or go straight to the grid while the battery is held full for outages. The first setting uses more of your own generation after dark; the second keeps the most backup in reserve. The inverter settings decide this, and the right one depends on how often your grid fails and how you are billed.

The paperwork is the same as for an on-grid system. Origian files the net-metering application and coordinates with the DISCOM from start to finish as part of the installation, and that work is included in the quoted price. You do not need to apply yourself.

Solar Hybrid costs more than Solar On-grid for the same array, because it adds a battery and a hybrid-capable inverter that a plain grid-tied system does not need. It costs less than Solar Off-grid for a comparable backup load, because it only has to carry the circuits you put on backup through an outage, not the whole building indefinitely with no grid to fall back on at all.

Battery-backed systems need more attention than grid-tied-only ones, which is why we cover them under an annual maintenance contract. What is guaranteed, and for how long, is set out on our warranty page. For how the work runs on site, see our installation process, or see what’s actually inside the installation. See it on a rotatable 3D model, including both the battery bank and the grid connection a hybrid system keeps.

A hybrid system costs more than an on-grid system with the same panels, because it adds a battery bank and a hybrid inverter. How much more depends mainly on the battery, and the battery depends on your answers in the sizing section above.

Four choices move the price most. The backup load, in watts, sets how much power the inverter must supply from the battery. The backup hours set how much energy the bank must store. The battery chemistry sets the cost of each unit of storage and how often the bank will need replacing. The array size, set from your bill, is priced the same way as on-grid.

Because the battery is sized to your circuits, Origian prices a hybrid system after the site survey rather than from a list. For reference, the solar system price guide lists Origian’s gross prices by system capacity; ask how a hybrid quotation differs from it for your site. Ask, too, for the battery, the inverter and the backup circuits to be itemised separately, so you can see what the backup itself costs.

There is no subsidy figure in any of this. Whether a system qualifies for a scheme depends on the scheme’s own rules and on your DISCOM, so the number to compare is the full price on the quotation.

A hybrid installation follows the same nine stages as any Origian rooftop system, with one extra decision made early: which circuits move to the backup output. The whole job typically runs 10 to 15 days once the order is confirmed, though the DISCOM’s approval, which Origian does not control, can stretch it.

1. First meeting. How a hybrid splits power between your loads, the battery and the grid. Bring a recent bill and your list of backup circuits.
2. Site visit. The roof, the shade across it, a shaded and ventilated place for the battery bank, and where the backup circuits sit in your distribution board.
3. Quotation. A written quotation for the array, the inverter, the battery and the backup circuits. The price is fixed here.
4. Document collection. Once you go ahead, Origian collects the papers the net-metering application needs.
5. Advance payment or loan processing. The advance is paid, or loan paperwork is completed for a financed system.
6. Installation. The structure, panels, hybrid inverter, battery bank and earthing go in, and the backup circuits are moved to their own output.
7. DISCOM documentation and approval. Origian files the net-metering application and follows it through to approval.
8. Synchronisation. The net meter is fitted and the system is synchronised with the grid.
9. Switch-on. The system goes live. Before handover, ask to see the changeover to battery tested with the grid switched off.

The three system types answer different questions. If outages are rare and you want the lowest cost for each unit of solar, on-grid is the simpler choice. If your site has no grid connection, or the grid is too unreliable to plan around, off-grid carries the whole load on its own array and battery. A hybrid solar system sits between them: grid savings most of the time, and a defined set of circuits kept running when the grid drops.

A useful test is the list from the sizing section. If it is a handful of circuits for a few hours, you are describing a hybrid. If it is everything in the building for days, you are describing off-grid, and the battery bank will cost accordingly. The longer comparison is in our guide to on-grid, off-grid and hybrid solar systems, and the on-grid and off-grid pages cover each option in detail.

A battery-backed system needs more attention than a grid-tied one, because the battery ages with every cycle and heat speeds that up. Under an annual maintenance contract, Origian visits every three months and commits to respond within 48 hours if you report a problem between visits. On a hybrid, those visits are the time to check the battery terminals, the ventilation around the bank and the inverter’s battery settings, alongside the panels. Details are on the annual maintenance page.