We present a conceptual design of a diode-pumped solid-state-laser (DPSSL) driver for an inertial fusion energy (IFE) power plant based on the minimized cost of electricity (COE) as determined in a comprehensive systems study. This study contained extensive detail for all significant DPSSL physics and costs, plus published scaling relationships for the costs of the target chamber and the balance of plant (BOP). Our DPSSL design offers low development cost because it is modular, can be fully tested functionally at reduced scale, and is based on mature solid-state-laser technology. Most of the parameter values that we used are being verified by experiments now in progress. Future experiments will address the few issues that remain. As a consequence, the economic and technical risk of our DPSSL driver concept is becoming rather low. Baseline performance at 1 GW$e) using a new gain medium [Yb3+-doped Sr5(PO4)3F, or Yb:S-FAP] includes a product of laser efficiency and target gain of (eta) G equals 7, and a COE of 8.6 cents/kW(DOT)h, although values of (eta) G greater than or equal to 11 and COEs less than or equal to 6.6 cents/kW(DOT)h are possible at double the assumed target gain of 76 at 3.7 MJ. We present a summary of our results, discuss why other more-common types of laser media do not perform as well as Yb:S-FAP, and present a simple model that shows where DPSSL development should proceed to reduce projected COEs.