Background
#A battery does not automatically turn a solar system into a backup-power system. For many single-family homes, property managers and smaller commercial buildings in Nidwalden, the first goal is self-consumption: solar power generated during the day is used later in the building.
Backup or replacement power is an additional system function. For that, inverter, battery, switching, grid isolation, supplied circuits and the electrical distribution must work together. If this question is only asked after the quote, offers are often compared that do not technically deliver the same thing.
For your roof
Does a battery pay off for you?
Add the battery in the calculator or leave it out. Self-consumption and payback are based on your consumption and address.
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What decides on storage
#The most important decision is the function: self-consumption, backup power or replacement power. Self-consumption means stored solar electricity is used later during normal grid operation. Backup power usually means limited supply for selected loads. Replacement power goes further and can keep defined circuits or parts of a building operating during a grid outage. Swissolar explicitly points out that standard systems are not automatically prepared for backup operation.
Electrical isolation determines safety. A system that continues supplying power during a grid outage must not feed back into the public grid in an uncontrolled way. Switching, grid / island operation, protection concept and labelling must therefore be planned by an authorised specialist. ESTI describes generation systems and energy storage systems as electrical installations with testing and documentation duties.
The supplied loads must be defined before sizing. A fridge, router, control unit or lighting has different requirements from a cooker, heat pump, lift, commercial refrigeration or charging station. The more loads are to continue during an outage, the more demanding battery size, inverter output, phase supply, sub-distribution and cost become. A serious quote therefore states which circuits are actually supplied during an outage.
When retrofitting, the existing electrical distribution is often the constraint. Not every older installation can be extended with a battery, backup switching and monitoring without modifications. Especially with tight meter spaces, old distribution boards, several sub-distribution boards or planned loads such as a heat pump and wallbox, an on-site survey is needed rather than pure online sizing.
Incentives must be checked separately from the technical decision. Nidwalden refers to its cantonal programme for building envelope and heating replacement as well as further incentive programmes; for photovoltaics, the national one-time remuneration via Pronovo remains a central element. Whether battery, control system or backup function is supported must not be assumed generally and must be checked before commissioning.
The process in five steps
#Tick off for your project
Define the target picture
before quoting, decide whether the battery should only optimise self-consumption or whether certain loads must continue during a grid outage. Record these loads in writing, including priority and desired runtime.
Survey the existing setup
electrical distribution, meter space, house connection, existing PV system, inverter, cable routes and possible sub-distribution boards are checked on site. For new builds or renovations, this belongs in early roof and electrical planning.
Choose the system variant
AC-coupled, DC-coupled, hybrid inverter, a simple backup socket or replacement power for defined circuits are different solutions. The variant must fit the PV system, usage profile, outage objective and future extensions.
Involve the grid operator and electrical specialist
notification duties, connection conditions, metering concept, protection concept and any switching are clarified before ordering. Especially for island or replacement-power functions, coordination must not start only at commissioning.
Complete documentation and testing
after installation, initial testing, measurement and test protocols, safety certificate, system diagram, operating notes, monitoring access and clear responsibilities belong in the handover. Owners and property managers must know what happens automatically during a grid outage and what does not.
Checked for your roof, not just read up on
Does a battery pay off for you?
Add the battery in the calculator or leave it out. Self-consumption and payback are based on your consumption and address.
Free and non-binding · no unsolicited calls
Rather talk directly? +41 78 615 90 58
Frequently asked questions
#Sources
#The responsible authorities are decisive. Always verify binding details – amounts, deadlines and conditions – for your specific property against the current status of the respective authority.