A:That is truly a How many angels can dance on the head of a pin" question. Condensation in a tent is the product of so many factorsdew point, temperature, humidity, wind, your own bodily exhalations... The simple fact is that ANY tent can form condensation, depending on the conditions.
Ventilation is the key. You keep air moving through the tent, condensation ceases to be an issue. That means pitching a tent so that the foot end points into any prevailing wind there might be. It means leaving some doors/windows unzipped. It means, well, carrying a light towel to mop up a little interior dew.
So, lets take a tent such as the Mountain Hardwear Lightpath 2 ($180). True, it is a two-person tent, but it is a SMALL two-person tent, so more room for you. Weighs about four pounds, which is not bad, and in my view fine for solo. The canopy is mostly mesh, so plenty of ventilation there. The fly offers full coverage, and even if you button it up completely, condensation will run down the slope of the tent wall and not really have much impact on you. In most conditions, you will not have a problem. I guarantee it.
Same for MSRs Hubba ($250). Its a true solo tent, so less interior volume, and frankly a higher opportunity for moisture. But it has great ventilation, and is very light (three pounds). Condensation CAN occur, but the odds are low. Same deal for REIs Quarter Dome T1 ($200) a very light (2 pounds 12 ounces), well-ventilated solo tent.
Ive even had good luck with Black Diamonds Lighthouse ($430) a very light (just over three pounds) single-wall tent that, thanks to good materials and good ventilation, vents very well. Could condensation form? Heck yeah. Id live with it, because I love the tent and usually it doesnt. A friend of mine and I were in it in June on Mount Shuksan, tent sealed up in 30-degree weather, we both are heavy breathers, but there was no condensation.