The individual's limit on elective deferrals is not the only limit. There is also a per-plan limit on additions. Your additions to the solo 401(k) are not permitted to exceed your net earnings from self employment. Net earnings are net profit minus the deductible portion of self-employment taxes.
Net earning in this case are,
$5.000.00 - ($5.000.00 * 0.9235 * 0.153) / 2 = $4,646.76
so your additions to your account in the solo 401(k) plan are limited to $4,646.76.
