Do I need to tell my insurer about my solar or battery? Yes — and the real risk isn't the premium.

For consumer home insurance you have a statutory duty to take reasonable care not to make a misrepresentation to your insurer, which applies when you apply for, renew or extend a policy. Because solar and a battery add materially to your home's rebuild cost and are treated as part of the building, they are exactly the kind of change you should disclose. The safest and simplest approach is to notify your insurer when the system is installed and raise your building sum-insured to include its full replacement cost. Your policy wording, or a quick call to the insurer, confirms exactly what they need to know.

Two things can go wrong. First, if you didn't disclose relevant information, an insurer may not be obliged to pay all or part of a claim, and in some cases can treat the policy as if it never existed. Second, and more commonly overlooked, if your sum insured is too low you become under-insured. ASIC's MoneySmart explains that most policies then pay only a proportion of your claim, and this applies to all claims, not just those above the insured amount. So a stale sum insured can quietly reduce even a small storm or water-damage payout, not just a total loss.

Your building policy generally covers the panels as part of the building against insured events such as hail, windstorm, theft and vandalism, provided your sum insured includes their replacement cost. What it typically does not cover is the equipment simply faulting, degrading or failing over time. A dud inverter, a battery that stops holding charge, or general wear are warranty matters, handled by the manufacturer or installer, not the home policy. Keep both safety nets in mind: insurance for sudden external damage to the building, warranty for the product's own performance. Check your policy's product disclosure statement for the exact insured events.

The sum insured is the maximum your building policy will pay to rebuild or repair your home, and you nominate it. MoneySmart advises working out an accurate sum-insured amount so you avoid being under-insured, and updating it after any change to the property, such as renovations or big purchases. After solar or a battery, ask your installer for the full supply-and-install cost of the system and lift your building sum-insured to absorb it, on top of the existing rebuild figure. Then review it every year, because rebuild costs drift over time and an accurate figure is what protects every future claim.

It might rise, and it might barely move. The change depends on your insurer, your home's value and your location, so there's no reliable one-size figure, and anyone quoting an exact dollar amount is guessing. The honest point is that the premium is not the real issue. Getting your sum insured right matters far more, because under-insurance proportionally reduces every claim you make. The cost of updating your cover is almost always small next to the payout you could lose by staying under-insured, so it's rarely a good reason to delay the call. Ask your own insurer for an updated quote to see your actual number.

It depends on the cause, and your policy wording is the final word. Sudden damage to your home from an insured event is generally covered as part of the building, up to your sum insured, so check which perils your product disclosure statement lists. But a battery that simply fails, degrades or stops working is normally a warranty matter handled by the manufacturer or installer, not your home insurer. Some insurers also ask specific questions about batteries or lithium storage, so it's worth confirming your cover directly. Keep your warranty documents safe and separate from your insurance, because you may need whichever one applies.