Please Help * Invalid account: #0 for network: Rinkeby - private key too short, expected 32 bytes

[Deamonk1]

Hi ,Please when i try compile hardhat.config.js i get the error : * Invalid account: #0 for network: Rinkeby - private key too short, expected 32 bytes Please what does it mean and how do i convert my Rinkeby private key in dot env to bytes
Any idea on how to solve this error and compile successfully . Thanks in Advance here's my code hardhat.config.js

/**

• @type import('hardhat/config').HardhatUserConfig
  */

require ('dotenv').config();
require("@nomiclabs/hardhat-ethers");

const { API_URL, PRIVATE_KEY } = process.env

module.exports = {
solidity: "0.7.1",
defaultNetwork: "Rinkeby",
networks: {
hardhat: {},
Rinkeby: {
url: API_URL,
accounts: ['${0xf302aC9c7a55B5A5a50BFb027696F307101df60A}']
}
}
}