That is not exactly true. It can be transmitted, and there are countries in Europe that are experimenting with it. The higher the current though, the greater the power loss. Indeed when you daisy chain the panels, each panel increases the voltage drop, assuming they are all properly polarized. In AC, when the power reaches substations, the voltage is reduced because the windings on the source are greater than the windings output, IIRC, but the current also is increased in the process. The same thing happens at the transformer outside your home. Larger offices and industrial sites have their own transformers to get the right voltage levels for the equipment they are running. I don't believe they are using copper on high voltage power lines though!
The main issue with DC, is that getting the voltage to such a high level, is not possible through windings on a transformer. They have to daisy chain the DC voltage generators, much like you are doing with your solar panels. The other issue with DC voltage, is that the infrastructure in place has already been dedicated to AC power, as are virtually all existing appliances and equipment. Mobile devices OTOH are all DC based, and computers have to transform the power from AC to DC. Large appliances such as washers, dryers and AC units in addition to industrial equipment runs best on AC power because of the high voltage/current that they require and the fact that AC motors cannot switch the magnetism in the coils without some clock driven or brush driven circuitry, and there are rather large thyristors and other semiconductors involved in the switching to enable this to perform the switching with higher breakdown voltages. Brushless motors are used in server fans and computers, because they do not generate ozone, and because they last longer, whereas brushed motors appear in toys such as RC cars, which will likely get much less use than an every day appliance.
The main point I was making initially, was the Edison was right about the dangers of AC, because of the myriads of deaths we encounter when power lines break, and now that the infrastructure in place has been dedicated to AC, sharing excess DC power is much more complicated, since we have to have the conversion from DC over to AC at every point that DC power is generated, due to the dedication of the current infrastructure that is in place. When you generate DC power from your solar panels, either you need excess battery strorage capability, or you can "sell" the excess back to the power generating company, or else it will go to waste, in the form of supplying more voltage than your tools and appliances actually need to provide satisfactory power for your usage.
So without the expensive conversion equipment or additional batteries, that is lost power that you might have otherwise been able to use when there is less sunlight available. Even with the conversion equipment, there is still a tremendous loss of power, because the conversion has some lag or propagation delay, and just like if you had one of your solar panels oriented with the same polarity as its neighbors, the voltage drop you would see there is similar to what happens during intervals in the power conversion process. Remember that AC runs at approximately 60 Hz, so when you are near a power substation, you will hear what sounds like a low A# pitch (A is 55 Hz), as the magnetized rods vibrate at that rate. So if your equipment is off by a few microseconds, that delay will result in loss of power.
