1. Solar cells are a little smaller and lighter than before.
2. Solar cells are little smaller and lighter than before.
3. Solar cells are much smaller and lighter than before.
(#3 is grammatical, right? What about #1 and #2? Are they grammatical? What is the difference between #1 and #2?)
1 and 3 are good.
For #2, custom demands that we use the article in this sentence.
All three sentences are grammatically correct, but there are some subtle differences in meaning.
1. "Solar cells are a little smaller and lighter than before."
2. "Solar cells are little smaller and lighter than before."
3. "Solar cells are much smaller and lighter than before."
In sentence #1, "a little" is used as an adverbial phrase to mean "slightly." It suggests that there has been a small decrease in both size and weight of solar cells compared to their previous state.
In sentence #2, the word "little" is used as an adjective to express the degree of difference in size and weight. It indicates that there is a small decrease, but it doesn't emphasize the degree as strongly as sentence #1.
Sentence #3 uses the word "much" to intensify the extent of the difference. It indicates that there has been a significant decrease in both size and weight of solar cells compared to their previous state.
So, the main difference between #1 and #2 is the level of emphasis placed on the degree of decrease in size and weight. Sentence #1 suggests a slight decrease, while sentence #2 is somewhat less specific, leaving room for interpretation. Sentence #3, on the other hand, strongly implies a significant decrease.