Simple solar solution

[foilandwater]

Hi, I'm a kite surfer and as a hobby I build weather stations that help us see the wind and ocean conditions at different spots. You can see my simple website here incase you're curious. The weather stations I build typically consists of 4 devices, I've listed their power requirements below. Important to note that a) all this equipment needs to run 24/7 and b) it will be installed at a remote site about 2 hours from my house so it should require little to no maintenance.

• Raspberry pi - 5V / 2.5A
• Base station for weather sensor - 5V / 1A
• TP-link SIM card router - 9V / 0.85A
• Hikvision IP camera - 12V / 0.4A

I calculate the total Watts and current to be 31.65W and 4.75A.

I have a requirement to install a camera in a location without any power, so I'm looking to build a solar rig that can power the above. My understanding is basic, and I live in the United Arab Emirates where it is sunny 99% of the time.

I have been given a quotation from a local solar shop for the following, does this sound reasonable?

• 3 x 170W panels
• Gel battery 200 AH
• Solar controller 60A

I few questions/thoughts I have:

• Does the above combination of equipment sound under specified, over specified or about right?
• I would prefer to use MPPT over PWM
• It would be ideal to monitor the solar controller remotely via the cloud / app for iPhone
• I could use something like this to power the 2 x 5V devices. I will need a similar device for the 9V router.
• Does it need to be a gel battery? Can I just buy a regular car battery?

Would really appreciate any support with this.

Thanks,
Sean.

 

[sunshine_eggo]

5V * 2.5A = 12.5W
5V * 1A = 5W
9V * .85A = 7.65W
12V * .4A = 4.8W

Total: 29.95W

Current changes with voltage, so 4.75A isn't relevant unless a votlage is involved.

If you had a 12V system, 29.95W/12V = 2.5A

29.95W * 24h = 719Wh of energy consumed per day.

at 12V, that's 719/12 = 60Ah

Assume 85% efficiency, 60Ah/.85 = 71Ah

I have been given a quotation from a local solar shop for the following, does this sound reasonable?

• 3 x 170W panels

510W of panels

• Gel battery 200 AH

A 200Ah GEL has 100Ah of usable capacity, so you'd have 1.4 days of power without charging.

• Solar controller 60A

510W /12V = 42.5A

60A controller would certainly cover that.

I few questions/thoughts I have:

• Does the above combination of equipment sound under specified, over specified or about right?

With the above numbers, you should be able to determine that for yourself.

• I would prefer to use MPPT over PWM

Why? MPPT lose their advantage in high heat conditions. Quality PWM might be the better value. I'm assuming the UAE is a hot place with good sun.

Critical that the charger be able to sense battery temperature and compensate for it.

Note that lead acid batteries experience notable cycle life deterioration at elevated temperature.

• It would be ideal to monitor the solar controller remotely via the cloud / app for iPhone

Agree.

• I could use something like this to power the 2 x 5V devices. I will need a similar device for the 9V router.

Yep and Yep.

• Does it need to be a gel battery? Can I just buy a regular car battery?

Car batteries are horrible for power applications. They are designed for very high current but very light discharges with immediate recharging to full. Car batteries are alos typically flooded meaning they have a liquid electrolyte that you would have to check very regularly and replenish. Yes, you could do this, but you'd need a large car battery, and you'd likely have to replace it regularly.

 

[foilandwater]

5V * 2.5A = 12.5W
5V * 1A = 5W
9V * .85A = 7.65W
12V * .4A = 4.8W

Total: 29.95W

Current changes with voltage, so 4.75A isn't relevant unless a votlage is involved.

If you had a 12V system, 29.95W/12V = 2.5A

29.95W * 24h = 719Wh of energy consumed per day.

at 12V, that's 719/12 = 60Ah

Assume 85% efficiency, 60Ah/.85 = 71Ah




510W of panels



A 200Ah GEL has 100Ah of usable capacity, so you'd have 1.4 days of power without charging.



510W /12V = 42.5A

60A controller would certainly cover that.



With the above numbers, you should be able to determine that for yourself.



Why? MPPT lose their advantage in high heat conditions. Quality PWM might be the better value. I'm assuming the UAE is a hot place with good sun.

Critical that the charger be able to sense battery temperature and compensate for it.

Note that lead acid batteries experience notable cycle life deterioration at elevated temperature.



Agree.



Yep and Yep.



Car batteries are horrible for power applications. They are designed for very high current but very light discharges with immediate recharging to full. Car batteries are alos typically flooded meaning they have a liquid electrolyte that you would have to check very regularly and replenish. Yes, you could do this, but you'd need a large car battery, and you'd likely have to replace it regularly.

Thanks a lot for this detailed reply, exactly what I was looking for! Very much appreciated.