Powering multiple sensors

Dear all, I am new to arduino, but am very interested in learning more. I am currently looking for a platform that would allow me to measure wind speed and direction, solar flux and power consumption at three different locations of a self powered system. For this I though I need a total of at least 9 sensors. 1 wind speed 1 wind direction, 1 solar flux, 3 current sensors, 3 voltage sensors. the voltage and current sensors will be needed to calculate the power. As 8 of these nine sensors will be analogue sensors I thought the arduino mega would fit my requisites as it has 16 analog inputs. However I am concerned with the power aspect, will the arduino be able to power all these sensors? If it can't can I power them from the power source that is powering the arduino? (a pack of 12v heavy duty batteries) but still use the arduino to read the values that the sensors output? Thank you all

You haven't said what the power needs are for the sensors. But given that the locations are spread out, then having each sensor powered in parallel from the input power to the mega would probably make more sense, with local voltage regulator at each location, and signal and ground from each brought back to the mega.

I have not put any details about the sensors because I have yet to choose what sensors to use. The wind sensor and solar flux might be self powered however they might need an amplifier. The current sensors I need to sense currents up to a max of 10Amps. and the voltages should not go above 20V. All the currents and voltages in my system are DC currents. If anyone has any suggestions on sonsors they are very welcome:) I was hoping of maybe using hall effect non invasive sensors for current but I have not yet found a suitable one. So does the arduino support a maximum of 100mA current distributed accross all the sensors I want to use? So your suggestion is to connect the sensor to the high voltage of the power supply, to the ground pin on the arduino and the output pin to one of the analogue input pins? sorry about my ignorance but I am an absolute novice. Thank you

Yes, you can get several hundred milliamp of 5V current for power (<800 total including the Mega’s needs), any more than that you risk overheating the regulator. Same for 3.3V.
Any signals coming back have to be in the 0-5V range.

Depending on the sensor: Create local regulated power for each sensor from the 12V batteries. Bring output back to arduino input, using resistor divider to bring it into 0-5V range if needed. Connect all grounds, preferably at one location.

Thank you so much for you help. As I have been looking around for the sensors to use I though I might share my thoughts. For wind speed I was looking to use something similar to these sensors http://www.inspeed.com/anemometers/Vortex_Wind_Sensor.asp and http://www.inspeed.com/wind_speed_direction/Vane.asp These both seem to be appropriate for the arduino as the Wind sensor emits a pulse which I read i can attach to an interrupt pin and the vane produces an output between 0.25 and 4.75V which is in the range of the arduino's input sensors. For solar flux I am thinking of using a pyranometer with amplified output to 0-5V While for voltage sensors I was thinking of using voltage dividers created by me as I can fine tune them for greater accuracy. Am I right or should I look for ready made products? such as this http://www.emartee.com/product/42082/Arduino%20Voltage%20Sensor%20Module ? What I am finding hard is to find a suitable current sensor. As I will need to measure at most 10 Amps and always DC I am struggling to find a 0-10A current sensor. Does anyone have any suggestions on this? Thank you, Al