add_filter( 'relevanssi_excerpt_content', 'wpsc_product_excerpt', 10, 3 );
function wpsc_product_excerpt( $content, $post, $query ) {
	if ( 'wpsc-product' === relevanssi_get_post_type( $post->ID ) ) {
		$content = $post->post_content . ( ! empty( $post->post_excerpt ) ? " $post->post_excerpt" : '' );
		if ( 'on' === get_option( 'relevanssi_expand_shortcodes' ) ) {
			$content = do_shortcode( $content );
		} else {
			$content = strip_shortcodes( $content );
		}
	}
	return $content;
}