Scientists at Spectrolab report development of multijunction solar cells exceeding 40% efficiency. PhysOrg.com (via Slashdot) reports on the research which tested the cells in concentrator applications where the cells were subject to high intensities of sunlight. Multijunction concentrator technology affords two advantages: 1) Substitution of low cost mirrors for high cost solar cells to reduce costs; and 2) Higher efficiency cells to produce more electricity in a smaller footprint.