Before you compare panels or prices, you have to decide what kind of solar system you need. The three main types, on-grid, hybrid and off-grid, work in different ways, behave differently when the power fails and cost different amounts. Choosing the wrong type is one of the most common reasons customers are disappointed with their system.
Key takeaways
- On-grid systems work together with the grid, have no batteries and are the simplest and most economical, but they switch off during a grid outage.
- Hybrid systems add batteries so selected loads keep running during an outage while the system still works with the grid.
- Off-grid systems run without the grid, on solar and batteries (often with a generator as backup), and are sized for the worst days.
- The right choice depends on how often the power fails, which loads must keep running, when you use electricity and your budget.
How an on-grid solar system works
An on-grid (grid-tied) system consists of solar panels, a grid-tied inverter and the usual protection and metering. During the day the panels produce power, the inverter converts it to AC, and your loads use it first. If the system produces more than you use, the surplus is exported to the grid where the rules allow it; when it produces less, the grid supplies the rest.
Standard grid-tied inverters are designed to shut down when the grid fails. This is a safety requirement, so that the system does not feed power into lines that workers believe are dead. The consequence is that a plain on-grid system gives you no electricity during a power cut, even in full sun.
Best for: sites with a reasonably dependable supply and mostly daytime use, such as offices, shops, schools and many factories, where the aim is to cut the electricity bill.
How a hybrid solar system works
A hybrid system adds a battery bank and a hybrid inverter (also called a multi-mode inverter). It uses solar power first, charges the batteries with surplus power and uses the grid as needed. When the grid fails, it can disconnect from the grid and keep supplying a protected set of loads from the panels and batteries.
Most hybrid systems power only chosen “essential” loads during an outage, such as lights, fans, a refrigerator and a router, rather than the whole building. Which loads, and for how many hours, decides how large the batteries and inverter must be.
Best for: homes and businesses that suffer frequent or long power cuts, or that must keep certain equipment running, and that still want to use the grid.
How an off-grid solar system works
An off-grid system has no connection to the grid at all. The panels charge a battery bank through a charge controller or an off-grid inverter, and the inverter supplies the loads from the batteries. Because there is nothing to fall back on, the system must be sized for the worst combination of low sunshine and high use, and many off-grid sites add a generator for long cloudy periods.
Best for: remote sites with no reliable grid, such as farms, tube wells and remote buildings.
Comparison at a glance
| On-grid | Hybrid | Off-grid | |
|---|---|---|---|
| Batteries | No | Yes | Yes |
| Works with the grid | Yes | Yes | No |
| During a power cut | Switches off | Supplies chosen loads | Not affected |
| Relative complexity and cost | Lowest | Medium to high | Highest for the same load |
| Typical use | Bill reduction | Bill reduction and backup | No grid available |
How to choose
- Count your outages. If cuts are rare and short, on-grid may be enough. If they are frequent or long, backup matters.
- List what must keep running. Decide which loads are essential and for how many hours.
- Look at when you use power. Daytime use suits solar directly; evening and night use needs batteries or the grid.
- Think about your budget now and later. A system can be designed so that batteries are added later, but the inverter must support it from the start.
- Check the rules. If you plan to export power, check the current requirements first; see net metering in Pakistan.
Mistakes to avoid
- Expecting an on-grid system to work during a power cut. It will not, unless it is a hybrid design.
- Running heavy loads from batteries without sizing for them. Air conditioners, motors and pumps draw large starting currents. Size the inverter and batteries for them or leave them off the backup circuit.
- Buying batteries before choosing the inverter. They must match in voltage and communication; see solar batteries: lithium vs lead-acid and our solar inverter guide.
Talk to us
Not sure which type fits your home, shop or factory? Tell us your electricity bill, your outages and your essential loads through the quotation form and we will recommend a system. See our solar solutions for residential, commercial and industrial sites.
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