Peakers aren't "profitable" per se, they're a result of the government granted monopoly given to power utilities. In california, at least, a brown or blackout caused by insufficient capacity can cost the utilities tens or hundreds of millions in fines so the peaker plants are a relatively cheap way to avoid having your margin wiped out in the summer. That said, I'm not sure 20MWh would really help replace any peakers although in the future they definitely will.