Solar Sizing

{
  "annualKwhToOffset": 10000,
  "asOf": "2026-10-11T14:31:36.963Z",
  "coveragePercent": 101.7,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "estimatedYearlyKwh": 10170,
  "installedKwDcWithWholePanels": 7.2,
  "notChecked": [
    "roof shape, tilt, azimuth and shading, which can cut output by 10 to 40% (peak sun hours must already reflect your tilt and location)",
    "seasonal and monthly production against your use, battery storage and net-metering rules",
    "…2 more"
  ],
  "panelCount": 18,
  "panelWatts": 400,
  "peakSunHours": 4.5,
  "reasons": [
    "kW = annual kWh / (peak sun hours x 365 x (1 - losses)); output = kW x peak sun hours x 365 x (1 - losses).",
    "Savings count only the energy you use: output beyond your use is valued at zero here (export credits vary by utility).",
    "…1 more"
  ],
  "roofAreaSquareFeetApprox": 324,
  "simplePaybackYears": 13.5,
  "source": "computed locally",
  "summary": "Offsetting 10000 kWh a year at 4.5 peak sun hours and 14% losses needs about 7.08 kW: 18 panels of 400 W (7.2 kW), producing about 10170 kWh a year. Savings about 1600 a year at 0.16 per kWh. Cost 216…",
  "systemCostGross": 21600,
  "systemCostNet": 21600,
  "systemKwDc": 7.079,
  "systemLossPercent": 14,
  "verdict": "COMPUTED",
  "yearlySavings": 1600
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://home-energy-calc.x402tookit.com/solar-sizing?annualKwh=10000&costPerWatt=3&panelWatts=400&peakSunHours=4.5&pricePerKwh=0.16'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://home-energy-calc.x402tookit.com/solar-sizing?annualKwh=10000&costPerWatt=3&panelWatts=400&peakSunHours=4.5&pricePerKwh=0.16' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fhome-energy-calc.x402tookit.com%2Fsolar-sizing
const res = await pay("https://home-energy-calc.x402tookit.com/solar-sizing?annualKwh=10000&costPerWatt=3&panelWatts=400&peakSunHours=4.5&pricePerKwh=0.16");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://home-energy-calc.x402tookit.com/solar-sizing?annualKwh=10000&costPerWatt=3&panelWatts=400&peakSunHours=4.5&pricePerKwh=0.16")
    print(res.status_code, res.text)