The most common surprise for new solar owners is that a standard grid-tie system switches off when the grid goes down, even on a sunny afternoon. If brownouts are part of life where you live, that changes which system you should buy.
Grid-tie
Panels and a grid-tie inverter, with no batteries. Your home uses solar power first and the grid covers the rest. This is the simplest and lowest-cost option, and the natural fit for net metering.
During a brownout the inverter shuts down automatically. This is a safety requirement called anti-islanding: it stops your panels from feeding power into lines that linemen may be working on.
Hybrid
Panels, a hybrid inverter and a battery bank, still connected to the grid. Solar runs your loads and charges the batteries. When the grid fails, the system keeps powering the circuits connected to its backup output. It costs more because of the batteries, but it is the option that actually solves brownouts.
Off-grid
No grid connection at all. Everything runs on panels and batteries, sometimes with a backup generator. It makes sense for farms, resorts, islands and sites far from the power lines. For a house that already has a grid connection, it usually costs more than a hybrid system for the same comfort.
Which one to choose
- You mainly want lower bills and brownouts are rare: grid-tie
- You want lower bills and backup power during brownouts: hybrid
- You have no grid connection, or it fails for days at a time: off-grid
Batteries: what to compare
- Usable capacity in kWh, not only the nominal figure on the label
- Chemistry. Lithium iron phosphate (LiFePO4) batteries are now common for home storage. Lead-acid batteries cost less up front but usually need replacing sooner.
- Cycle life and warranty terms, in writing
- Which circuits are backed up: the whole house, or essential loads such as lights, refrigerator, fans, wifi and a water pump
Planning for brownouts
Make a list of the appliances that must keep running in a brownout and for how many hours. That list, not a generic package, is what a hybrid system should be sized against. Include it when you request a quote.