Know Your Exact Solar Cost — Instantly

This single choice sets three things at once: your currency, a realistic starting range for your electricity bill and rate, and the main government incentive program (if any) that applies where you live. Solar costs and electricity prices vary enormously by country — a system that costs $18,000 in the United States might cost the local-currency equivalent of $6,000 in Pakistan or $30,000 in Japan, purely because of labor costs, import duties, and local market maturity. Picking your country first means every slider and every dollar figure that follows is already in the right ballpark for where you actually live.

This is the single most important number in the whole calculator, because it's how we work out how big a system you actually need. We divide your bill by your electricity rate to estimate your monthly electricity usage in kWh, then size a system that would offset that usage given your local sun exposure. Bigger bill, bigger system, bigger price tag — but also bigger savings. You can type any amount directly (there's no upper limit), or drag the slider for a quick estimate.

Your rate does double duty in the math. First, combined with your bill, it tells us how much electricity you actually use. Second — and this is the part people often miss — it directly determines how much each kWh your panels produce is worth. Someone paying 30¢/kWh gets a far faster payback than someone paying 8¢/kWh, even with an identical system, because every unit of solar power they generate is worth almost four times as much. If you're not sure of your exact rate, check a recent utility bill — it's usually printed per unit, or you can back it out by dividing your bill total by your usage in kWh.

A panel in full, unobstructed sun all day produces meaningfully more electricity than an identical panel that spends part of the day in shade from trees, neighboring buildings, or chimneys. Rather than asking you to estimate exact shading percentages and separately pick a regional sun-hours tier — two numbers most people can't answer precisely anyway — we combined them into one plain-language question: is your roof mostly in full sun, partial sun, or shaded? Full Sun assumes no meaningful obstruction; Partial Sun knocks off roughly 15% of expected output for occasional shade; Shaded assumes closer to 40% lost output for a roof that spends real time under trees or buildings. This, combined with your country's baseline sun hours, is what determines how large a system you need to hit your target output.

Not every roof costs the same to mount panels on. Asphalt shingle and standing-seam metal roofs are the easiest and cheapest to work with — most installers have standard hardware for both. Concrete or clay tile roofs take longer and require more careful (and more expensive) flashing work to avoid cracking tiles, and flat roofs need a ballasted or tilted racking system that adds hardware cost neither pitched option needs. We add a modest cost premium for tile and flat roofs to reflect this, while leaving shingle and metal as the baseline.

Budget, Standard, and Premium reflect real differences in panel efficiency, manufacturer warranty length, and expected degradation over 25 years — not just a marketing label. Budget panels are the least expensive per watt but typically carry shorter warranties and slightly faster efficiency loss over time. Premium panels (from manufacturers like SunPower, REC, or Panasonic-tier brands) cost more upfront but produce more power per square foot and tend to still be performing well after 25+ years. Standard sits in between and is what most homeowners choose. This setting changes your per-watt equipment cost directly.

A grid-tied system with no battery is the cheapest way to go solar and works well if your goal is purely to lower your bill — excess power you don't use gets sent to the grid (and, depending on your local policy, may earn you a credit). Adding a battery lets you store that excess power for use after dark or during a grid outage, which matters if backup power is a priority or if your utility's export credit isn't generous. Batteries are a genuinely large line item — often a third or more of total project cost — so we show it as a separate toggle rather than bundling it in by default.

This one changes not just the number but which number matters most to you:

Cash gives you the best long-term return, since there's no interest to pay — you see your net cost, payback period, and lifetime ROI directly.

Loan spreads that same net cost over a term you choose (5–20 years) at an interest rate you set, and we calculate a real amortized monthly payment — the same math a bank would use — plus a plain comparison of that payment against what you're currently spending on electricity, so you can see your actual monthly cash-flow impact rather than just an abstract "total cost."

Lease/PPA is the one case where we deliberately don't give you a savings number, because we'd be making it up. Lease and power-purchase-agreement pricing is set entirely by the provider's own rate structure, not by system cost — two providers quoting the same roof can offer very different lease terms. We show you the reference equipment cost so you have a benchmark, and tell you plainly to get quotes from a couple of providers to compare instead of trusting a generic number.

Many countries and regions offer some form of solar incentive — a tax credit, a rebate, a feed-in tariff — but eligibility rules change constantly and vary by state, province, or even utility. Rather than assume you qualify, this toggle defaults to off everywhere, including in countries with well-known programs. Flip it on and we'll apply your country's typical incentive percentage to your estimate — but we also label exactly what that program is called and add a note to confirm you still qualify, since a stale assumption here can throw your whole estimate off by 20–30%.

Electricity prices don't stay flat — historically they've climbed a few percent a year in most markets, which means the value of the power your panels produce actually grows over time, not just stays constant. The rate-increase field lets you model that (3% a year is a reasonable global default, though you can adjust it). System lifespan (20, 25, or 30 years) sets how many years of savings we sum into your lifetime totals — 25 years is the typical manufacturer warranty period and the most common assumption used industry-wide, though most panels keep producing meaningful power well beyond that.

The total generating capacity of the panels we'd size for your home, in kilowatts. This is the number installers will use as a starting point when they do their own site-specific design.

System size divided by a standard 400-watt panel rating, rounded up. Real installers may use panels rated anywhere from 350W to 450W+, so your actual panel count could differ slightly — this is meant as an intuitive sense-check, not a precise parts list.

Your estimated annual electricity offset in the first year, at today's rate — before any of the annual rate increases you modeled compound in.

How many years it takes your Year-1 savings to fully repay your net system cost. This is the number most people care about most — everything after payback is, in effect, free electricity. (Not shown for Lease/PPA, since you never fully "own" the system cost the same way.)

Total electricity savings summed across your full system lifespan (20–30 years), with your annual rate increase compounding year over year. This is usually the biggest, most attention-grabbing number — and it's real, but remember it's spread across two or three decades, not a lump sum.

Lifetime savings minus net cost, expressed as a percentage of net cost. A 200% ROI means you get back three times what you paid over the system's lifetime (your original cost, plus 200% more on top) — genuinely one of the better long-term returns available to an average homeowner, which is a big part of why solar adoption keeps growing even as one-time subsidies phase in and out.