The Intersolar North America event was in full swing this week, and that means there's a lot of news to cover for solar manufacturers. With investors hoping a weak first half of the year turns into a strong second half, any good news would be welcome. Let's get right to it.

A peek into the second quarter
The second quarter is widely expected to be a weak one for solar manufacturers; ReneSola (NYSE: SOL) gave us a peek into just what to expect as earnings season begins.

The company cut its total solar wafer and module shipments to a range of 290 MW to 300 MW, from a previous expectation of 330 MW to 350 MW. Revenue expectations were also cut drastically from a range of $280 million to $300 million to a range of $235 million to $245 million. As a result, gross profit expectations fell 8%, to between 17% and 19%.

Signs of a U.S. awakening: China perks up
Yingli Green Energy (NYSE: YGE) is certainly pumped up about its progress in the U.S. market and announced it has reached 250 MW of cumulative shipments in North America. As bad as solar news has been worldwide this year, in North America Yingli delivered more modules in the first half than all of 2010.

All of that adds up to an expected 15% market share for the Chinese solar manufacturer. If the U.S. can grow demand quickly in the next few years, that should be great for Yingli investors.

The solar market is also growing in China, where LDK Solar (NYSE: LDK) signed 35 MW of deals this week. That may be relatively small, but in emerging markets we'll take anything we can get to build up sales.

New products hit the market
Trina Solar (NYSE: TSL) announced that it is prepared to ship its new Trinamount rooftop system to installers in the U.S. There are three versions of the product, which will be used on tile roofs, pitched roofs, and commercial PV systems. Trina expects this to help lower overall system costs and highlights the industry's focus on balance of system costs, not just panel costs.

Suntech Power (NYSE: STP) launched two new panels for sale in the Americas. The first is a 245-watt panel designed to reduce shading on the cell surface to improve light absorption. The other is a 290-watt panel for utility-scale projects that includes a higher output wafer and better light-induced degradation.

Suntech also increased its limited warranty from five years to 10, hopefully a sign that the company has increased confidence in its products.

ReneSola also said it is shipping the new Virtus wafers and modules, which have cell efficiency rates of 17.5% to 18.2% for the high-end cells. This continues Chinese manufacturers' renewed focus on efficiency in an effort to catch up to industry leader SunPower (Nasdaq: SPWRA).

Last and maybe most notable is the announcement from United Solar, a subsidiary of Energy Conversion Devices (Nasdaq: ENER), that it has reached a cell efficiency of 16.3% for a small-area cell. This is still a long way from making it into an actual panel, but I've criticized Energy Conversion Devices in the past for making panels that are way behind the efficiency curve. So this week I applaud the company's move and hope it will help turn around the company's financial position. I'll be watching closely.

Foolish bottom line
Until we start hearing from management just how the second half of 2011 is shaping up, it's going to be hard for solar stocks to get out of their funk. But for now solar investors can take comfort in the fact that manufacturers are slowly and steadily improving products and seeing improving conditions in important markets like China and the U.S.