LIVING IN AN APARTMENT WITH NO GARDEN OR ROOF SPACE, AND STILL GENERATING AN APPRECIABLE AMOUNT WITH 17x 15W AND 10x 30w AMORPHOUS SOLAR PANELS. FIXED TO THE WALL FACING EASTWARDS, AND IN THE WINDOWS ON THE WEST SIDE.
30W refers to the amount of energy (measured in Watts) the panel would make on a cloudless day at around noon in the middle of the Sahara Desert in Summer where Mother Earth receives about 1000 Watts of energy in a square meter of land per hour.
So please don't expect this panel to do the same in the United Kingdom. But do expect some power all day long, maybe only 1w- per hour on a sunless cloudy day, and about 20w+ per hour on a scorching summers day when obstacle free pointing at the sun around noon, and variations therein during other daylight conditions.
Here is the OHM'S LAW equation to work out Power(Watts)=Voltage(Volts)xCurrent(Amps)xTime(Hour) (P=VIt) for those of you interested.
Amorphous solar panels are excellent panels for beginners and professionals alike.
They start generating their first 1mA (1/1000 of an Amp) just before the Sun rises on the horizon on a clear spring morning for example, with enough Voltage to start the charging process(es).
These amorphous solar panels concentrate on building up their voltage first and thereafter boost the current flow. (Mono and Poly tend to do the reverse, building up a huge current flow in bright sunlight (about 2+ times more than Amorphous panels), yet struggling with keeping the voltage up, when the clouds are about).
They hardly loose any power when they get hot, nor when behind a window. Useful if you live in an Apartment as a 'glass heater' in winter, and a generating 'blind/curtain' in summer.
These Solar Panels could also be called 'Cloud Panels' as they generate quite well with the reflected light from the clouds, when the Sun is on the other side of the building for example.
Shadows and/or obstacles are also not a problem, as long as the 'amorphous strips' are mostly cut by the Rays/Sunshine/Cloudshine/Light, you will always make some 12v electricity.
Useful for keeping the batteries on constant charge during daylight hours.
And when there are no clouds, just pure Rays of Sunshine, they produce about 5 to 10 times more current than on a cloudy or bright-dark-side part of the day.
If you are thinking of using this panel for charging a 12v battery with less than 38AH (amp-hours), you should use a voltage regulator to keep the small battery from overcharging and/or overusing/overdischarging.
Then you'll be able to sleep well knowing your led lights will be ready to use all year, for years to come.
So what can the 12v battery do? If you connected a cigarette-lighter socket to the + and - terminals (or into the Load terminals of your voltage regulator), you could then power/charge any 12Volt device that has a cigarette-lighter plug on the end.
For example you could directly run your laptop (daily or only in emergencies) off the 12v battery, using a 'dc power regulated adapter', setting the device to the voltage your laptop uses and fitting the right plug. The other end would plug into the cigarette-lighter socket.
You may find that in winter or cloudy days, you would like to increase electricity production. By connecting more amorphous panels together, more current is generated, as the voltage will remain approximately the same.
With the extra panels they even keep a decent/sufficient voltage on dark rainy days, though the current generating is very, very low.
With the extra panels you will be generating loads more around the Summer Solstice or bright sunny days, when the days are longer than the nights, and will probably have more than enough electricity to charge the battery(s), so you might want to convert the extra power to 240V mains power.
Do remember though, you can only take out what you put in!
You could use a 12v dc, 240V ac (modified/pure sine wave) 'Inverter' for transforming the stored power in your battery to 240V ac to power a small laptop and modem, TV, Hifi, up to the rated Inverter Wattage. (eg 300W).
The other option is to directly connect your solar panels to a 12v dc, 240v ac 'Grid Tie Inverter' which transforms the 12vdc electricity to 240Vac and passes it to the mains grid for storage (when your electricity meter moves backwards!!) or for immediate use (fridge, fan, lights, laptop, etc). 300W 12v grid tie inverters require about 400mA to start transforming.
To change when the grid tie inverters come on, you could add large diodes in series, on the solar dc side. Each diode takes up a voltage (0.2-0.5V schottky). Tuned to about 14 volts before gti comes on, so that the 12v batteries in the same solar circuit always get charged. Especially important around the Winter Solstice, from Haloween to St Valentine's day, when the nights are longer than the days.
Keeping batteries and/or inverters as close to the solar panels as possible will result in short cables, increasing efficiency. (Power Loss=CurrentxCurrentxResistance).
PS If you have spotted a mistake or have other comments, please do let me know, Cheers Raffaelo.