You should be able to repair this, not buy new panels. After you get them clean and dry, tape the ends. I would think that cleaning with a bleach water solution and then getting the area compleatly dry will help solve the problem. I used a metal tape to cover the holes on the end of the panels, when I put mine together. I found it at the hardware store, was suggested by other posters, not duct tape. I didn't poke holes in the tape as some of them suggested doing, that didn't make sense. I had a bunch of tape left over so I used it to cover any air leaks I found, really helped and doesn't look to bad.
We have been getting an abnormal amount of rain this year, yet the panels are still clear, no leaks in the greenhouse.

You should have been instructed when you bought the product that the ends should always be sealed with tape. Mine are and the panels are pushing fifteen years now and still clean. I can't even fathom cleaning them and getting algae out with water or air pressure.

If you use bleach you`ll degrade the uv stabilizers in the poly..significantly reducing its life expectancy and voiding any warranty you may have on the cover.
A compressor would probably rupture the poly long before you could blow anything out.

Ok, upon closer inspection, it seems most of the crude is actually on the outside of the panel. That is a good thing =) What do people use to scrub the dirt off of the panel?

Once clean, look into buying U channel to cap off the ends.

Right......U and J channel is a must, but they should still be capped off with water repellent tape before seating in the channels. We did this on the advice of a g'house engineer who came down when we erected a custom made unit and it has saved us a lot of grief with the polycarb walls.

Dealing with the outside is much easier!

Get a regular sponge mop like for a kitchen floor, fill a bucket with mild detergent and water, and get to work. I would rinse as you go so no soapy film dries on them.

Sue

Remove the end caps and blast a high pressure washer up each individual channel leave for a week or so to dry out refit and seal caps better done during June/July when its hot just done mine you do get wet but so its 25oC Brian.

The proper way to "cap" off polycarbonate is to put a foil tape on the top of the sheets. This should then be covered with a U channel. For the bottom of the sheets you should use a vent tape and cover this with a U channel. The only difference is that this U channel should have 1/8" holes drilled in the bottom of the U. Polycarbonate will get condensation between the sheets under certain circumstances. The reason you use the vent tape and drill the holes in the bottom U is so that this moisture can drain. If you do not vent the bottom U the moisture will become trapped and get moldy. These materials are readily available from any polycarbonate dealer. I clean the inside and outside of my polycarbonate greenhouse every year with a mild soap solution (I use Dawn) and a soft brush that was made to wash cars. This will assure that your light transmission will not be diminished by the buildup.

I bought a used polycarbongreenhouse and all of the panels except the roof panels were in good shape i have algae about 1 inch up and have been used qtips and dawn to remove it not perfect but most is gone i plan to tape the ends once they are clean