DayStar Technologies ( DSTI) surged 24% Monday as trading continued to heat up in the small-cap company several days after a sales deal. DayStar said Thursday it sold some TerraFoil solar cells to Blitzstrom of Germany. The news sent the stock up from $6.88 at the close Wednesday to $13.55 in midafternoon action Monday. Volume was heavy, with 4.3 million shares changing hands Monday against a three-month daily average of 337,000, according to Yahoo! Finance. DayStar, of HalfMoon, N.Y., said the companies will collaborate on marketing efforts and explore development opportunities for its so-called Photovoltaic Foil product line. Terms weren't disclosed, though DayStar said the deal is "contingent on DayStar's ramp-up of its production capacity" and "calls for monthly delivery of TerraFoil escalating in volume through the end of 2008 with price based on a variable market-competitive pricing mechanism." DayStar surged $2.50 to $13 Monday.