First of all, congratulations for living in a nice house with a roof and/or a garden you must have access to a roof. When you live in an apartment building, you might get away with sticking something on the wall, but the efficiency will greatly drop due to angle.
Second, I did look into it (for ideological reasons), but there’s a lot (of costly hardware) to it. Also, these ‘panels’ come in many cells that you will have to group together in a weather-resistant fashion yourself, costing time, knowhow, and materials/money.
Third, a 200 GHash/s mining rig consumes 150 watts, or - ignoring everything said above - a $150 investment. 200 Ghash/s is about 0.0004 bitcoin per day, or $0.25 per day, or a little under two years just to break even. Ignoring the slowly declining profit margin and the investment of the rig.
For comparison: Without free energy, we pay about $0.27 per kWh. Running 150 watts for a day is about 3.6 kWh AKA about $1 per day. So modest mining, even for ideological reasons, costs about $0.75 per day nett.
Of course farming on dedicated equipment doesn’t cost nearly as much energy, but I predict it’s a lot less profitable too. Let’s do a thought experiment. Dropbox users are willing to pay $100/year for 1TB of storage. Someone writing a MegaUpload app on top of MaidSafe needs to be competative, so they will charge $50/year per terabyte, and give $40/year/TB to the harvesters. The chunks are stored at least 4 times, so that’s $10/year/harvester/TB. A 4TB drive + NAS hardware costs $300. Earning $40/year makes you need to harvest for 7.5 years to break even.
But even if you already have that NAS sitting there catching dust. No investment needed. Just 30 watts of non-idle power consumption AKA 300.024365*0.27 = $71 per year in electricity costs. Hence, earning just $40 (AKA losing $31) per year makes dedicated harvesting not profitable either.
Oh well, I was letting myself go a bit. Sorry for that. 