The short version
Solar-only is the cheaper ticket and the smaller prize: it typically touches around 20% of a working business's bill, because the sun gives you five strong hours and your business pays for twenty-four. Solar + storage costs more and changes the outcome — your midday power covers your evening, your demand charge drops, and brownouts stop mattering.
The full arithmetic of the 20% problem is here: why solar alone covers so little.
Side by side, fairly
| Solar-only | Solar + storage | |
|---|---|---|
| Upfront cost | Wins. Panels and an inverter — the cheapest entry into solar. | Costs more on day one; the battery is real money. |
| Share of bill covered | ~20% typically. Daytime only; evenings stay full price. | Far more. With thermal loads shifted too, total bills typically fall 50–65%. |
| Your surplus | Exported at a loss — credited at roughly half (or less) of the rate you pay to import. | Stored and used — worth about double exporting it. |
| Demand charge (business) | Untouched. Your worst 15-minute peak usually lands outside solar hours. | Shaved 30–50% by a battery timed to your peak. |
| Brownouts | Most grid-tied solar-only systems shut off with the grid. | Rides through — lights, tills and chillers keep running. |
| Financed cash flow | Good — small loan, small saving. | Better where evening load is real: the bigger saving covers the bigger repayment, and under EaaS you're cash-positive from month one with nothing upfront. |
Where solar-only honestly wins: operations that genuinely sleep when the sun does. An office that empties at 5pm. A school. A day clinic. If that's you, buy panels, skip the battery, and spend the difference on a daytime heat pump instead — it does more for the bill than a battery you'd barely cycle.
The third piece most comparisons miss
Your biggest single load is probably thermal — hot water, process heat, cooling. Move it into the sunshine and the comparison changes again: a heat pump running at midday on your own panels turns ₱1 of free-ish electricity into about ₱4 of heat, and a thermal battery stores it for tonight at a fraction of the cost of lithium. That's the full system — and it's why we tell people the real choice isn't "panels vs panels + battery." It's "panels vs a system."
Who we are
Karnot Energy Solutions Inc. is a Philippine energy company in Mapandan, Pangasinan. We don't sell panels for a living — we design and install the system around them: iVOLT solar + battery bundles, iSTOR thermal storage and iHEAT heat pumps, across the Philippines, the UK, the US and Canada.
Questions we get asked
Is solar without a battery still worth installing?
Sometimes. A purely daytime operation gets good value from panels alone. A home or business with evening usage typically sees solar-only touch just ~20% of the bill.
How much more does storage cover?
Storage carries midday power into the evening and shaves the demand charge. Combined with a daytime heat pump for thermal loads, total bills typically come down 50–65%.
Why not just export the surplus?
Export pays roughly half (or less) of what import costs you. A stored kilowatt-hour is worth about double an exported one. The new rules made approvals faster and raised the cap to 1 MW — they didn't change that arithmetic.
Storage costs more — how do I afford it?
Financed properly, the saving covers the repayment. Under EaaS we install at no upfront cost and you pay monthly, set lower than your current bill — cash-positive from month one.
Get the comparison run on your bill
One free site survey. We log your loads and show you both options' real numbers for your site — and if solar-only is genuinely your better buy, we'll say exactly that.
Book a free site surveyRelated: The 20% arithmetic · Solar batteries in the Philippines · Commercial solar + storage