Last week, I hopped over to London to check out EcoFlow's latest plug-in solar and battery gear, now that plug-in solar is about to become legal in the UK. But what really caught my eye was how pure plug-in solar is already looking like last season's tech, with hybrid systems promising bigger savings.

Don't get me wrong, pure plug-in solar - solar panels hooked to a microinverter feeding your home - still has its place. The catch? A classic mismatch: your house wants power in the morning and evening, but the sun peaks at midday when you're probably out humming Dolly Parton's "9 to 5." If you work from home, you're golden; if not, you're leaving free energy on the table.

Solar can cover some base load (that always-on stuff like the fridge, Wi-Fi router, and vampire devices), but the allowed size is tiny - 800W in most allowed spots, up to 1,920W in Colorado. That won't make you energy-independent, not by a long shot.

The real trick is time-shifting: store that midday sun for the evening rush. Batteries can do that, and they can also charge from the grid when power's cheap. If you have a time-of-use (TOU) or time-of-day (TOD) tariff, you might not even need solar.

But here's the rub: every charge and discharge cycle loses energy to heat and inefficiencies. Round-trip efficiency is about 80-90%, so for every 1 kWh you plug in, you get 0.8-0.9 kWh back. That's why you want to buy low, sell high - or at least store cheap and use pricey.

Let's do some real math with Con Edison rates. My 12 kWh "Tower of Power" would need 15 kWh to fill (accounting for losses), costing $0.783. That 12 kWh would otherwise cost $3.3432 in summer or $2.0532 in winter. So each refill saves about $1 to $2.50 a day. A smaller 3 kWh setup saves just $0.30 to $0.60 a day. And that's before surcharges and the cost of the gear itself.

Speaking of costs: basic plug-in solar starts around $300 for 180W, up to $2,000 for 800W. Add a battery and smart controller, and you're looking at $2,000 for a 5,024Wh system, plus installation near $1,000. Expandable to a massive 90kWh, but that'll cost you.

To make that back, you need the best tariffs and to work the system. Fortunately, it's app-controlled and mostly automatic - charging when cheap, discharging when pricey. And the 10-year warranty is a nice touch.

This isn't buying LED bulbs; it's more like installing insulation - a long-game investment. As for payback, I've run numbers for various US and UK spots, and most systems should pay for themselves in about 5 years, barring extreme sun or prices. After that, you're saving money.

But remember, not everyone's in it for the money. Some want to shrink their carbon footprint; others, like me, just want power where there isn't any. And with outages on the rise, backup power is a bonus.

Scale matters too: don't overbuy storage if you're a light user, but heavy users can benefit from bigger buffers. So, do the math, check your tariffs, and decide if you're ready to play the long game.