06-17-2008, 12:54 PM
Information on Solar Power
When buying a Solar Panel it is important to buy one that can produce adequate electricity for the purpose of maintaining charge in your battery - and remember that although a solar panel will still produce electricity on a dull day the amount it produces will be reduced - considerable on a very heavily overcast day.
All panels that I have seen put out nominally 12 volts of electrical pressure. This should be continuous irrespective of the light shining on the panel, but in marginal conditions this may drop. However a panel can also produce small or large amounts of electricity called amps. This equates to a radio dry cell battery that can produce enough electricity to power a radio(less than 1 amp), but it won't
start a car engine!!! However the car lead acid battery produces huge amounts of electricity (unless it is 'flat') that can start a car (needing well over 20 amps and can be up to 70 amps depending upon car and conditions) and also has ample to run a radio.
Different pieces of equipment use different amounts (amps) of electricity.
Your water pump at full belt uses about 4 amps.
Your radio 2 to 4 amps depending on how posh it is.
Your TV 4 to 8 amps depending ditto.
Your Strip Light less that 1 amp per strip.
Your spot bulb between 1 and 2 amps each bulb depending on brightness and type.
These two (amps and volts) can be combined together to say how much energy or power is involved. This is measured in watts. They combine using the equation:
Watts = Amps x Volts.
The more equipment you use the more amps you use (and because it is all 12 volts) the more energy is taken from you battery. This is why if you have lots of equipment in use you flatten your battery. Add up the amps each item of equipment uses. If, for example, this comes to 10 amps (e.g. TV, 2 strips and 2 bright spots), with an 85 amps per hour battery (85Ah) you will get theoretically 8.5 hours of use (10 amps for each hour) - theoretically because other factors are involved like how old the battery is and how well charged it was to start with.
Solar Panels
Panels are sold by the amount of electrical energy they produce - 10 watt, 20 watt, 30 watt. The bigger panels are multiples if the 10 watt panel. They produce energy because they contain circular metal plates coated with special chemicals that produce electricity when light shines upon them. Ignore any bobbly plastic on the surface layer - these are to act as lenses to concentrate the electricity onto each solar or photo cell.
As all are giving producing a nominal 12 volts - using the equation above and assuming a bright (not necessarily sunny) day:
the 10 watt panel gives out just under 1 amp,
the 20 watt, gives out just over 1.5 amps
the 30 watt gives out exactly 2.5 amps.
Over an typical effective 8 hour charging day,
the 10 watt panel produces 8 amps in total.
the 20 watt panel produces 15 amps in total.
the 30 watt panel produces 25 watts in total.
During the day you will usually not be using the battery much. The amps produced during the day will in part replace the amps used at night by
TV/lights/pumps/etc.
If you used 20 amps during the evening your 85Ah capacity battery drops to 65 Ah and the 10 watt panel replaces 8 amps so that it goes back to 73 amps.
At the same rate after 5 days you will end up with 25 amps in your battery. This means a pretty flat battery (you can never get all 85 amps out) but may be ok for lights.
On the other hand if you used 20 amps from your 85 Ah battery which leaves 65 amps, and used a 30 watt panel which replaces 20 amps you will be effectively keeping your battery fully charged at 85 Ah.
A 20 watt panel after 5 days would be in the middle with 55 amps left. Lights and radio would be fine but TV would be struggling.
If you started with a fully charged battery:
1. 10 watt panel - If just using lights and the odd bit of radio, over
a weekend this would be OK, but battery would need fully rechargeing
when you got home.
2. 20 watt panel - If using light and the odd bit of radio, over a 5
days this would be ok, but battery would need fully charging. With TV
it would be OK for weekend but struggling after 5 days
3. 30 watt panel - should cope OK for all 5 days.
When buying a Solar Panel it is important to buy one that can produce adequate electricity for the purpose of maintaining charge in your battery - and remember that although a solar panel will still produce electricity on a dull day the amount it produces will be reduced - considerable on a very heavily overcast day.
All panels that I have seen put out nominally 12 volts of electrical pressure. This should be continuous irrespective of the light shining on the panel, but in marginal conditions this may drop. However a panel can also produce small or large amounts of electricity called amps. This equates to a radio dry cell battery that can produce enough electricity to power a radio(less than 1 amp), but it won't
start a car engine!!! However the car lead acid battery produces huge amounts of electricity (unless it is 'flat') that can start a car (needing well over 20 amps and can be up to 70 amps depending upon car and conditions) and also has ample to run a radio.
Different pieces of equipment use different amounts (amps) of electricity.
Your water pump at full belt uses about 4 amps.
Your radio 2 to 4 amps depending on how posh it is.
Your TV 4 to 8 amps depending ditto.
Your Strip Light less that 1 amp per strip.
Your spot bulb between 1 and 2 amps each bulb depending on brightness and type.
These two (amps and volts) can be combined together to say how much energy or power is involved. This is measured in watts. They combine using the equation:
Watts = Amps x Volts.
The more equipment you use the more amps you use (and because it is all 12 volts) the more energy is taken from you battery. This is why if you have lots of equipment in use you flatten your battery. Add up the amps each item of equipment uses. If, for example, this comes to 10 amps (e.g. TV, 2 strips and 2 bright spots), with an 85 amps per hour battery (85Ah) you will get theoretically 8.5 hours of use (10 amps for each hour) - theoretically because other factors are involved like how old the battery is and how well charged it was to start with.
Solar Panels
Panels are sold by the amount of electrical energy they produce - 10 watt, 20 watt, 30 watt. The bigger panels are multiples if the 10 watt panel. They produce energy because they contain circular metal plates coated with special chemicals that produce electricity when light shines upon them. Ignore any bobbly plastic on the surface layer - these are to act as lenses to concentrate the electricity onto each solar or photo cell.
As all are giving producing a nominal 12 volts - using the equation above and assuming a bright (not necessarily sunny) day:
the 10 watt panel gives out just under 1 amp,
the 20 watt, gives out just over 1.5 amps
the 30 watt gives out exactly 2.5 amps.
Over an typical effective 8 hour charging day,
the 10 watt panel produces 8 amps in total.
the 20 watt panel produces 15 amps in total.
the 30 watt panel produces 25 watts in total.
During the day you will usually not be using the battery much. The amps produced during the day will in part replace the amps used at night by
TV/lights/pumps/etc.
If you used 20 amps during the evening your 85Ah capacity battery drops to 65 Ah and the 10 watt panel replaces 8 amps so that it goes back to 73 amps.
At the same rate after 5 days you will end up with 25 amps in your battery. This means a pretty flat battery (you can never get all 85 amps out) but may be ok for lights.
On the other hand if you used 20 amps from your 85 Ah battery which leaves 65 amps, and used a 30 watt panel which replaces 20 amps you will be effectively keeping your battery fully charged at 85 Ah.
A 20 watt panel after 5 days would be in the middle with 55 amps left. Lights and radio would be fine but TV would be struggling.
If you started with a fully charged battery:
1. 10 watt panel - If just using lights and the odd bit of radio, over
a weekend this would be OK, but battery would need fully rechargeing
when you got home.
2. 20 watt panel - If using light and the odd bit of radio, over a 5
days this would be ok, but battery would need fully charging. With TV
it would be OK for weekend but struggling after 5 days
3. 30 watt panel - should cope OK for all 5 days.