Solar Coin is a crypto currency specifically intended to stimulate solar energy production. Each Solar Coin represents the equivalent of 1 MW/hour of solar electricity. Coins can be obtained by mining like any other crypto currency, but the vast majority of coins, 99.4% of them, are reserved and held in non circulating accounts (wallets) to be exchanged for proof of production of solar energy, one coin for one MW/hour of electricity produced, certified by independent verification.
The Sustainablog has an article about it
Solarcoin.org is the official site.
The coin is mined like other crypto currencies – it is based on the code of Litecoin. In addition to the cryptographic proof-of-work typical of crypto currencies, there is also proof-of-production of solar energy, which may be used to claim coins – one MW/hour of solar energy produced and certified for one Solar Coin. This makes the coin much less energy intensive to produce than for instance Bitcoin, which has been criticized of being energetically wasteful.
The basis for Solar Coin is a White Paper, which argues that an energy based currency would be more stable than either debt based currencies or gold (asset) backed ones. That paper is not specifically limited to solar energy but it does make the point that an energy backed currency would make sense for countries that produce a majority of their energy from renewable sources.
The White Paper, titled DeKo: An Electricity-Backed Currency Proposal is available here
The coin was launched in January 2014.
Another article appeared on GreenBiz.com