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Balcony solar kits: what you get and which size to buy

For most homes an 800 W kit is the sweet spot. It covers the always-on power a typical home uses during the day without sending much to the grid for free. Go bigger only if your home uses a lot of power while the sun is up.

Updated October 2026

What’s in a kit

  • One to three panels.
  • A microinverter (sometimes two, or several small ones).
  • A cable with a standard plug.
  • Mounting hardware, sometimes sold separately.
  • Optional: a battery, an app, an energy meter.

400, 800 or 1,200 watts?

Kit sizeWhat it coversBest for
400 WRouter, fridge on a sunny day, chargersSmall apartments, tight railings, testing the idea
800 WThe always-on load of most homes, most of the dayMost people
1,200 WAlways-on load plus some daytime useHomes with people in during the day, or a battery

In California our model gives an 800 W south-facing railing kit 803 kWh and $207 a year. A 1,200 W kit makes 1,205 kWh but saves $238, because more of its power arrives when nobody can use it.

Checklist before you buy

  1. Check your state. Is plug-in solar allowed, and from when? State map.
  2. Check the size limit. Usually 1,200 W of output. Colorado allows 1,920 W.
  3. Check the certification. Ask for UL 3700 or the equivalent your state names, for the complete kit, not just one part.
  4. Check your spot. Which way does it face, and how many hours of direct sun does it get? Direction guide.
  5. Check your lease or HOA. Some laws protect you, many don’t. Renters guide.
  6. Check the mount. Will it fit your railing and hold in strong wind? Mounting guide.
  7. Run the numbers. Calculator.

Common questions

Can I start small and add a panel later?

Only if the inverter can take the extra panel and you stay within your state's size limit. Adding parts to a certified kit can also take it outside its certification, so check with the maker first.

Is a bigger kit always better?

No. A bigger kit makes more power at midday than most homes can use, and the extra goes to the grid. In California a 1,200 W kit makes about 50% more than an 800 W kit, but saves only about 15% more ($238 vs $207 a year in our model).

Should I buy a kit before my state's law takes effect?

If your state requires a certified kit, buy one that meets that rule, or wait until it's in effect and certified kits are on sale. Buying early risks owning a kit your utility can object to.

What does 'UL listed' on the box mean?

It can mean a single part is certified, not the whole kit. Ask which standard and which product: UL 3700 is the one written for plug-in solar.

Sources