Solar Off-grid: power that does not depend on the grid
Solar Off-grid is what you install when the grid cannot be relied on, or is not there at all. It is a complete supply system, and it is designed load-first.
How an off-grid system works
Panels generate direct current, which a charge controller uses to charge a battery bank at the correct voltage and rate. An inverter then draws from the bank to produce alternating current for your normal wiring and appliances. Generation and consumption are decoupled by the battery, which is what allows the system to run at night.
Because there is no grid to fall back on, every element has to be sized for the worst case rather than the average one: the array must recharge the bank even on overcast days, and the bank must carry the load through them.
Sizing starts with the load, not the roof
An on-grid system can be any size: a small one simply saves less. An off-grid system cannot: if it is undersized, the lights go out. So the design process runs backwards from a load schedule.
- Which loads must never stop? Lights, fans, refrigeration, pumps, communications, medical equipment.
- For how long without sun? This sets the days of autonomy the bank must provide.
- What is the surge demand? Motors and compressors draw several times their running current at startup, and the inverter must survive that.
Only once that schedule exists can the battery bank, array and inverter be specified. Any quotation given before it is guesswork.
Where off-grid makes sense
Properties with no connection
Areas with long or frequent outages
Loads that must not be interrupted
Batteries: what we install, and the warranty
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.
What off-grid costs you, honestly
Off-grid is the most expensive way to buy solar energy. You are paying for storage, which is both costly up front and finite in life, and for redundancy, because the system has to cope with bad weather on its own.
If your grid supply is actually reliable and your goal is a smaller bill, an on-grid system will do that for considerably less money. If you want net-metering savings AND backup for a defined set of loads rather than the whole building, Solar Hybrid is usually the better fit and costs less than sizing a full off-grid system to do the same job. Off-grid is worth its cost specifically where the grid is unreliable or absent altogether — not as a general upgrade to a working connection.
Battery-backed systems need more attention than grid-tied 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, the mounting and earthing hardware the warranty depends on. See it on a rotatable 3D model, including where the battery bank sits on an off-grid system.
Common questions
What is a Solar Off-grid system?
A Solar Off-grid power plant generates, stores and supplies electricity independently of the utility grid. Panels charge a battery bank through a charge controller, and an inverter draws from that bank to run your loads. It is a self-contained supply rather than a way of reducing a bill.
How is off-grid different from a hybrid system?
A hybrid system keeps its grid connection and uses a battery only for backup, so it can still import and often export. A true off-grid system has no grid connection at all and must therefore be sized to carry the full load through cloudy periods, which makes it considerably larger and more expensive.
How long will an off-grid system run my house?
Backup duration is a function of battery capacity against the load you are running, not of the panel array. A system sized for lights, fans and a refrigerator will last far longer than the same battery running air conditioning. Sizing starts by deciding which loads must stay on.
How long do solar batteries last?
Battery service life is quoted in charge cycles rather than years, and depends heavily on chemistry and how deeply the bank is discharged each day. Batteries are the component you should expect to replace within the life of the panels, and that replacement belongs in your cost planning from the start.
What makes an off-grid solar installation reliable over the long term?
Four things, in order of how often we see them go wrong: correct sizing against a real load schedule rather than a guess, a battery chemistry and depth-of-discharge suited to daily cycling rather than occasional backup, a charge controller and inverter rated with headroom for motor startup surges, and a workmanship warranty that actually names what is covered. A system that looks cheaper on the quote but skips one of these is usually the more expensive one within a few years.
Tell us what must stay running
Off-grid design starts with a load schedule. Book a survey and we will build one with you, then size the system against it.