Rooftop solar is sold as one product but comes in meaningfully different forms. The choice that matters most for a home is between an on-grid system and a hybrid one, and it is worth understanding before you look at quotes, because the price difference is large and so is the behaviour.
On-grid: the bill-reduction machine
An on-grid system has panels and an inverter, and no battery. Power goes to your loads first, and whatever you are not using is exported to the grid through a bi-directional meter. Because there is no battery — the most expensive and shortest-lived component — it is the cheapest way into solar and needs almost no maintenance.
There is one behaviour that surprises people, and it is not a fault. When the grid goes down, an on-grid inverter shuts down too. This is a safety requirement: it prevents your system feeding power into lines that a utility worker may be repairing. So an on-grid system will cut your bill substantially and will do nothing for you during a power cut.
Hybrid: solar plus backup
A hybrid system adds a battery and a hybrid inverter. Solar charges the battery first, surplus goes to the grid, and during an outage the battery supplies your home automatically. You get the bill savings and the backup from one installation.
The cost is real. For the same panel capacity, expect a hybrid setup to run substantially more than on-grid — commonly in the region of 40 to 60 per cent more — with almost all of that difference in the battery and the inverter. Batteries also have a finite life, so there is a replacement cost somewhere in the system's future that on-grid simply does not have.
- On-grid: cheapest, no backup, near-zero maintenance
- Hybrid: bill savings plus outage backup, materially higher cost
- Off-grid: no utility connection at all, rarely right where a grid exists
Sizing is two separate calculations
This is where hybrid installations disappoint people. Panel capacity is sized against your electricity consumption. Battery capacity is sized against what you want to keep running, for how long, during an outage. These are different questions and answering only the first leaves you with a system that saves money but empties its battery in twenty minutes.
The practical approach is a backup audit: decide what genuinely must stay on. Lights, fans, router, fridge and a few sockets is a modest and affordable load. Adding air conditioning changes the battery size — and the price — dramatically, because cooling is simply a much larger load than everything else combined.
How to decide
Ask how often your supply actually fails, and how much those failures cost you. If outages are rare and brief, an on-grid system plus the inverter you may already own is usually the rational choice — you are not paying for a battery to sit idle.
If outages are frequent or long, or if you run a clinic, a shop, or medical equipment at home, hybrid pays for itself in avoided disruption rather than in units of electricity. The same applies if you work from home and an outage means lost income.
- Reliable supply, want a lower bill — on-grid
- Frequent or long cuts — hybrid
- Medical equipment or work-from-home dependency — hybrid
- Already own an inverter and battery — on-grid may be enough
You can often start on-grid and add storage later
This is worth knowing before you commit. In many cases an existing on-grid system can be upgraded by replacing the inverter with a hybrid unit and adding a battery, rather than starting from scratch.
If budget is the constraint today but outages bother you, ask specifically whether the system being quoted can accept a battery later, and what that upgrade would involve. The answer varies with equipment, and it is much cheaper to plan for than to retrofit blindly.
The short version
On-grid buys you a smaller bill. Hybrid buys you a smaller bill and the lights staying on. Decide which problem you are actually solving, size the battery against a real backup audit rather than the whole house, and ask whether today's system can take storage later.