Company: FTCI
Filing Date: 2025-05-01
Form Type: 424B5
Source: 0001193125-25-109046
Chunk: 25

Company: FTC Solar, Inc.
Filing Date: 2025-05-01
Form: 424B5
Chunk 25
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 issuance under our 2021 Stock Incentive Plan and    
 613,022 shares of common stock reserved for future grant or issuance under our 2021 Employee Stock Purchase Plan; |

| • |     | 219,653 shares of common stock issuable upon exercise or vesting of options, having a weighted average exercise                               
 price of $19.73 per share (with 196,465 of such options being exercisable, having a weighted average exercise price of $21.27 per share); and |

| • |     | 1,566,439 shares of common stock issuable upon vesting of restricted stock units, having an estimated grant date 
 fair value of $5.70 per share.                                                                                   |

S-16

DESCRIPTION OF THE SECURITIES THAT WE ARE OFFERING

We are offering up to 3,318,881 shares of common stock at an assumed offering price of $3.42 per share, which was the closing price of our
common stock on Nasdaq on April 29, 2025, for aggregate gross proceeds of $11,350,576. The following description of our shares of common stock summarizes the material terms and provisions thereof.

Common Stock

For a description of the
rights associated with the common stock, see “Description of Capital Stock” in the accompanying base prospectus. Our common stock is listed on the Nasdaq Capital Market under the symbol “FTCI.” The transfer agent for the
common stock is Continental Stock Transfer & Trust.

S-17

PLAN OF DISTRIBUTION

We have entered into the Sales Agreement, dated as of May 1, 2025, under which we may offer and sell shares of our common stock from time
to time through Wainwright as the sales agent. Pursuant to this prospectus supplement and the accompanying base prospectus, from time to time we may offer and sell shares of our common stock having an aggregate gross sales price of up to
$11,350,576.

The Sales Agreement provides that sales of our common stock, if any, under this prospectus supplement and the accompanying
base prospectus may be made in sales deemed to an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act, including sales made directly on or through the Nasdaq Capital Market, the existing trading
market for our common stock, or any other existing trading market in the United States for our common stock, sales made to or through a market maker other than on