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Because the number on the box is raw cell capacity, and getting it out of a wall socket costs you something. The inverter that converts DC to AC runs at roughly 85–90% efficiency, so a 1,000Wh unit realistically delivers 850–900Wh to an appliance. Cold weather and very high draw take a little more. We quote what a unit actually delivers rather than what the box claims — that gap is most of the reason spec-sheet shopping goes wrong. Compare on real capacity.

Briefly, and expensively. Two things work against you: heating elements and motors draw far more than a fridge does, and anything with a motor spikes to two or three times its running wattage the moment it starts. A 1,500W space heater will flatten a 2,000Wh station in a little over an hour. For air conditioners and pumps you need to check the surge rating, not just the continuous one. Work out the running watts before you shop — what common appliances actually draw.

Longer than most people expect, provided it is LiFePO4. That chemistry is rated for roughly 3,000–4,000 full charge cycles before it falls to 80% of its original capacity — used weekly that is decades, used daily it is closer to ten years. Older NMC lithium-ion units manage nearer 500–800, which is why we flag the chemistry on every unit we cover. The difference explained.

Divide the battery size by the panel wattage, then add about a third. A 200W panel into a 1,000Wh battery is five hours on paper — call it seven in practice, because panels rarely hit their rated output outside of a clear day, a cool temperature and a near-perfect angle. It is the most oversold number in the category, and the reason an undersized panel in a bundle is worth catching before you buy. Panels and kits.

Yes — there is no separate technology, only a bundle. That is not automatically a bad deal: buying the pair together is often cheaper than buying them apart, and the connector and voltage are guaranteed to match. But the panel in a bundle is sometimes the cheapest one the brand makes, and undersized for the battery it ships with. We price every bundle against its two parts bought separately. Solar generators.

Depends which of the three you are buying. A portable power station, no — it is a battery with sockets on it. A plug-in solar kit going into an existing outdoor outlet, generally no either, though that varies with local code. Home battery backup that feeds your existing circuits, yes — the transfer switch or panel interlock is licensed work in most places, and it is the cost people forget when they compare it against a $15,000 installed system.

It depends on your state and your utility. Utah passed a law explicitly legalising small plug-in systems without a formal interconnection agreement, and other states have bills moving. Everywhere else it comes down to your utility’s own rules and local electrical code — which is not the same as being banned, but does mean checking before you spend. We track the position state by state — check yours here.

Affiliate commissions when readers buy through our links, at no extra cost to you. It does not decide what we recommend and it does not buy a place in a comparison — we cover brands that pay us nothing, and Bright Saver, a nonprofit that sells at cost with no affiliate programme at all, is still the cheapest route into plug-in solar we have found. How we research.