A lot to say about solar power. As with a lot of renewable energies, personal project will not pay for themselves except with intensives or DIY with second hand material.
People are generally wasting energy and doesn't realize how much energy is a kWh because it's cheap, as it's the case about gasoline when it's cheap. What I have for 7kWh :
- 3.5 days of TV+DVB-T+Wifi AP+Ethernet hub
- 5 days of computer (personal + professional, screens included)
- 10 days of freezer
- 18 days of refrigerator
- 36 days for 4 alarm-clocks
- 97 days of water filter
Some here can drive several miles with 7kWh.
In this site you can read some interesting information :
Photovoltaic solar PV panels in The Netherlands
and some examples of 1kWh use in this page :
Photovoltaic panels in the Netherlands - what can one kilowatt hour do for you
Here is my solar system :
groar's solar panels thread - EcoRenovator
It will pay back for itself because I will have a tax credit and sell the produced kWh 5 times the kWh I buy.
Since I'm producing, I'm also noting my consumption. In winter I'm producing in 1 week (7 days) what I'm consuming in 1 night... In summer I should produce 80% of my consumption. If I improved my consumption before being a producer, I improved even more noticeably by improving my heating. See :
http://ecomodder.com/forum/showthrea...html#post82050
Before my roof integrated 3kWh installation I wanted to build a geek project : having my firewall running with no CO2 and no nuclear waste. Here is the calculation and why I never did it :
DIY 60 watt solar panel - EcoRenovator. Now a little system, when you can get second hand panels and a little grid tied inverter, can be interesting to nullify a part of your constant consumption : see
my diy pv set-up - EcoRenovator (not mine).
Finally there is several things to understand on panels and inverters to understand low cost panels aren't interesting when you invest in a 25 years project : my panels' production is guaranteed at 80% during 25 years.
2 panels with the same Wp (Watt peak) rate will not produce the same quantity : Watt peak rate is the production with 1kWh/m˛ at 25°C and different brand will produce differently at different intensities (mono/poly-cristalin). The temperature will modify the production : the hotter the lower the efficiency, from -0.3 to -0.6% per °C and the panels can easily be at 75°C, ie -14 to -26%.
Inverters have different efficiencies and properties. The quality of the mppt (max power point tracker) will permit to maximize the power recovered from the panels. Older had max efficiency range near their maximal input, now this range is broader. When grid tied, they have to synchronize with the grid and some stop very fast at each perturbation and take time to resynchronize (up to a couple minutes).
Finally when several panels are attached in a string, the weakest will lower the total production a lot, so the panels have to be homogeneous which is very unlikely with low cost panels. If a panel dies then you will not be able to find an identical one and you will have to remove 2 panels if they are organized in two identical strings (my inverter has two independent strings with two independent mppt).
Nowaday if you want to save money without having to invest a lot (in time and/or money) then "hypowatt" your electric consumption.
Denis.