If some would be so
>kind to help me answer these
>two questions I would appreciate it.
>
>Hypothetically, If I have one 120 Watt
>Panel working at 80% efficiency =
>100 Watts for 10 hrs per
>day. This equals 1 K/Hr per
>day and 30KW/H per month that
>I would not being buying from
>my utility. Is this correct?
No. PV modules typically only convert the energy availible from sunlight into electricity with an efficiency of around 14% to 23% at standard test conditions. When it is at its greatest intensity sunlight strikes the Earth at a rate between 600 to 1000 watts per square meter. Most 100 watt PV modules measure about a square meter give or take. Solar thermal panels, which rely on the infrared spectrum, can reach efficiencies of 80%.
Something more important to consider is the number of hours of equivilent full rated power output per day which is subject to varibles such as; a given region, the seasons, the manner in which the PV module is oriented in relation to the Sun, the number of hours it is in full unshaded sunlight and, the big one - weather.
So to put this into some kind of perspetive. Where I live in eastern NC. solar south is between 7 and 12 degrees west of south on a compass. A 100 watt PV module; mounted in such a way so that a 2"x4" block cut square (about 8" long), placed with its end against the face of the PV module at 12:00 noon on the shortest day of the year (Dec. 21) will cast no shadow and, the PV module is exposed to full sunlight on a cloudless day with no haze, from 8:00 am to 4:00 pm, will produce approx. 350 watt hours.
During the summer on the longest day (June 21) if all I did was lay the PV module down to compensate for the suns higher angle and, weather conditions were the same, the 2x4 block would cast no shadow at 1:15 pm and the PV module would produce approx. 600 watt hours.
The trick is to "tune in" the PV module as close as possible to being perpendicular to the sun at all times of the day but, trackers are not cost effective for all regions or locations. In some case's it would be more cost effective to spend that money on more PV modules.
>As far as components go for a
>interty system I know I need
>solar panels and a intertying inverter
>such as the Sunnyboy SMA 1800.
>What else do I need?
Start by contacting your electric power supplier. Each one has different rules or policiy's concerning how an RE system is "tied on" as well as how they compensate for the power provided from the RE system. You will need disconects between the PV module and the inverter and between the inverter and the meterbase. There may be a need to add a transfer switch as well. Oh! it wouldnt be a bad idea to spend the $40 and get a the most recent NEC handbook and study it, Article 690 in particlar.
Did any of the links I gave you before help? I thought for sure the rendered schematic in the Homepower article about "Solar Cheese" would be helpful. How is your research going by the way?