My source was someone telling me a few years ago how it works. It may not be fully accurate. I looked it up and in short, this is how it seems to work in Sweden:
If you are producing energy from solar cells, wind mills, bio fuel, small scale water energy etc, you can apply for an electricity certificate, dimensioned after your capacity. Every MWh gives one certificate. Then you can sell your surplus energy on the market. You will also sell your certificate (see below) and get more income.
Everyone are required to buy a certain amount of certificates based on your own usage. This is referred to as a duty quota (or if it is quota duty?), and is decided by the parliament. Normally your electricity company takes care of this and puts some fee on your electricity bill, but you can also register to do it yourself. If you don't have enough certificates, you will have to pay a fee. You also pay a yearly administrative fee for buying certificates.
So, the producer and the buyer comes to an agreement. The producer sells surplus energy and/or certificates. The price on each certificate needs to be reported to the authorities who publish statistics, e.g. on Internet. At the beginning of the next year, the buyer "cashes in" the bought certificates. If the demand is higher than the supply, the market may be out of certificates. The penalty fee then is 150% of the average certificate price the past year. For the first two years of this system, there was an upper limit, this year 240 SEK ($30) per certificate. This is to prevent inflation in certificates. If you buy more certificates than you need, you can save them for next year.
Based on this, things look good for a producer. This system was brought into use in 2004, so maybe the part about unfair conditions related to the earlier situation and this system tries to fix it. I still believe you need to make some serious investments in technology if you want to distribute your own electricity, and maybe someone who has a surplus is required to register as a producer, invest in the technology and apply for certificates?