New to Solar, need help with my set up.

[sunshine_eggo]

@DThames has it.

@70oldsracer, in addition to shade, bad weather kills. On-site usage kills. You were up there Sunday. Did you use any additional power from the system? Charge cell phone, power anything additional to the mentioned items? If so, that usage + the lack of charging for two days means you likely tapped your battery capacity.

 

[70oldsracer]

Since I’m only drawing 20 watts, should I start by getting a smaller inverter? Right now I have a 750 watt inverter.

 

[sunshine_eggo]

Since I’m only drawing 20 watts, should I start by getting a smaller inverter? Right now I have a 750 watt inverter.

That might help. You could keep the 750W but powered off for when you're up there and might need a little more power.

Something I also forgot to mention, there's an efficiency loss in addition to inverter idle burn. This is typically about 85%, so if you're using 20W*24h=480Wh, it's actually about 480Wh/.85 = 565Wh. For maximum efficiency, you want an inverter with a max continuous power of about 3X your continuous load.

@DThames suggestion of powering directly from the battery is also valid. The nano is 24V, so you could buy a cheap 12V-24V converter. If your camera is 12V, you could possibly run it directly off the battery, but I would buy a 8-40V to 12V converter to give it a consistent 12V rather than let the input voltage vary with battery voltage.

 

[70oldsracer]

That might help. You could keep the 750W but powered off for when you're up there and might need a little more power.

Something I also forgot to mention, there's an efficiency loss in addition to inverter idle burn. This is typically about 85%, so if you're using 20W*24h=480Wh, it's actually about 480Wh/.85 = 565Wh. For maximum efficiency, you want an inverter with a max continuous power of about 3X your continuous load.

@DThames suggestion of powering directly from the battery is also valid. The nano is 24V, so you could buy a cheap 12V-24V converter. If your camera is 12V, you could possibly run it directly off the battery, but I would buy a 8-40V to 12V converter to give it a consistent 12V rather than let the input voltage vary with battery voltage.

So I’ll need more like a 1500 watt inverter?

 

[sunshine_eggo]

So I’ll need more like a 1500 watt inverter?

You're confusing energy with power.

Wh is energy.

W is power.

If you're burning 30W continuously and never more, a 100W inverter would work.

Also, there are pure sine wave (PSW) and modified sine wave (MSW) inverters. PSW produce clean power like the power company and are more expensive where MSW produce a wave form with big steps in it and is cheaper. MSW tends to be less efficient especially if powering motors and some equipment doesn't like it at all.

 

[Vigo]

We are probably talking way over what's been asked now but it's also my understanding that if your 'ac' devices (i.e. they have a 'wall plug') are really DC devices powered by switch mode power supplies, they actually don't really care if you run them on PSW or MSW. Hopefully that's not a huge misunderstanding.

Most 'wall warts' or 'power adapters' or any power cord that has a big box anywhere along the way, are usually AC-to-DC conversion devices. If so, they should have their output voltage written in the 'fine print' on the housing somewhere. Anything that runs on 12v you could switch direct to battery if you wanted, although the gain on low-power devices might be too tiny to waste the time changing the wiring. Some appliances have the ac-to-dc hardware built in instead of on the power cord, which means you have to try a little harder to even figure out how they work.

As far as optimizing what's already there, since your 'loads' are so small that you could actually power them through the solar controller's load port, you may consider wiring your inverter's power wires off the controller's load port. This would put a hard limit on how much power the inverter could actually make (before smoking the charge controller on the way out), but what it would allow you to do is use the adjustable 'load disconnect' and 'load reconnect' voltage setpoints of the solar controller to protect your batteries from a damaging level of discharge. You could simply put a fuse smaller than the load ports' current rating in the line to prevent you from 'forgetting' that you just put a low ceiling on the inverter and accidentally breaking the solar controller. You could also open the inverter and hardwire the on/off switch circuit through the load ports on the solar controller to accomplish the same thing without limiting the 750w inverter down to ~200w. Most inverters do have a low voltage shutdown built in but it's often 10.0-10.5 v and not adjustable on small/cheap inverters. Draining your batts to that voltage and leaving them like that for days will seriously shorten their lifespan.

If your daily input is LESS than your daily consumption you are doing 'deficit charging' where the batteries' state of charge gets lower and lower from one day to the next until the load finally fizzles out from low voltage, and this is WORSE than draining a battery and charging it up a few days later because it means the batteries were potentially at a low state of charge for weeks! Although, how bad 80lbs of batteries has to get before it won't run 20w of load from sundown to sunup is an open question. ? As long as your daily solar input actually exceeds your daily consumption, your batteries could basically 'go to crap' and still be able to get you through one night with 20w of load.

If you have a multimeter you could measure the actual consumption of your inverter both at 'idle' and with the loads plugged in, to determine whether it's worth the trouble to downsize it to a smaller one. Most meters can directly measure amps up to 10a, and since your loads are so small you should be able to simply run the whole inverter power circuit through the meter without needing a current clamp or other separate measuring device.

I think adding another solar panel is probably a simpler and more complete solution than doing anything on the load side, given that the load is already so minimal.

 

[sunshine_eggo]

As far as optimizing what's already there, since your 'loads' are so small that you could actually power them through the solar controller's load port, you may consider wiring your inverter's power wires off the controller's load port.

This is NEVER recommended.

 

[70oldsracer]

This is NEVER recommended.

I am going to get the exact wattage draw numbers and maybe you can tell me if another 100 watt solar panel would do the trick.

 

[sunshine_eggo]

If you got the 30A MPPT, the answer is yes. Doubling your solar doubles your daily production and allows for greater utilization. You might still tap out after two days of rain/clouds/crap PV, but it will help for sure.

 

[70oldsracer]

@DThames has it.

@70oldsracer, in addition to shade, bad weather kills. On-site usage kills. You were up there Sunday. Did you use any additional power from the system? Charge cell phone, power anything additional to the mentioned items? If so, that usage + the lack of charging for two days means you likely tapped your battery capacity.

So I hooked up a POE switch over the Labor Day weekend and another camera just to see if it would work. I had it hooked up like that for a few hours, so there was definitely an additional drain on the batteries. I guess that paired with the rain and cloudy weather for over two days, caused it to drain the batteries down. I’ve had the ubiquity and the one camera running since they end of May and this is the first time I’ve had an issue.

 

[sunshine_eggo]

You've likely discovered you have a 1 to 1.5 day reserve. If you used any additional power while you were there the first day, that's going to put you over the edge when there's bad weather.

What camera system? I'm looking for an alternative to my Blink cameras.

 

[70oldsracer]

RLC-510A | 5MP Person/Vehicle Detection Smart PoE IP Camera

Meet Reolink RLC-510A, a smart outdoor/indoor PoE security camera with person/vehicle detection, 5MP Super HD, clear night vision, audio recording and more.

m.reolink.com

Great camera and a really good price. That’s the pic from my blind. The camera I’m using there is the 810 model with 5x optical zoom. I do need to set the panel at the right angle for the area which I’ve read is 42 degrees and I’m sure it needs to be cleaned.

 

[DThames]

Just a general statement of design and there are no hard and fast numbers. But consider that at best you get less than the panels rated watts when the panel is pointed at the sun on a good day. Anytime the sun is off angle (pretty much all of the time) you get less. If the sky conditions are less than ideal, you get less. If you have any tree or structure shading you get a LOT less. With a fixed array, I stated you would be good to get 80% for 4 hours a day. In those 4 hours, I would like to charge my batteries (fully) in 3 or 4 hours. So I would want maybe 3 or 4 times the panels that I would "need" under good conditions. Consider then that if the battery was large enough to carry you through 2 or 3 days of poor conditions, on the 3rd or 4th day the sun comes out for a few hours, I want to quickly get my battery back where it can go for 2 more less than good days.

Original poster, you have not stated how clear the panel's sky view is. It needs to be free of shade. Another 100w in parallel might be all you need to get by on most situations. I suggest you look around and see if you can get used 300w sized panels in your area. $75 to $100 is a typical rated for a large used panel.

Note, I have a used 290w panel on a 12v system at our hunt shack. It has no 24/7 load. We have a 500w cheapo inverter for 120v LED lights, which is about all it is for, that and phone charging. The battery is sized to provide us with lighting over a 5 day weekend with medium solar conditions. We are in a wooded area and the panel only gets 2 or 3 hours of sun if we are lucky.

Next month I am taking 4 additional large used panels and set up a charging station for a golf cart that we plan to take with us. So fun adding that system to the camp. That system will have a 24v battery that we can charge during the day and dump to the golf cart at lunch or in the evening. We might also use it for a slow cooker during the day.

 

[70oldsracer]

Just a general statement of design and there are no hard and fast numbers. But consider that at best you get less than the panels rated watts when the panel is pointed at the sun on a good day. Anytime the sun is off angle (pretty much all of the time) you get less. If the sky conditions are less than ideal, you get less. If you have any tree or structure shading you get a LOT less. With a fixed array, I stated you would be good to get 80% for 4 hours a day. In those 4 hours, I would like to charge my batteries (fully) in 3 or 4 hours. So I would want maybe 3 or 4 times the panels that I would "need" under good conditions. Consider then that if the battery was large enough to carry you through 2 or 3 days of poor conditions, on the 3rd or 4th day the sun comes out for a few hours, I want to quickly get my battery back where it can go for 2 more less than good days.

Original poster, you have not stated how clear the panel's sky view is. It needs to be free of shade. Another 100w in parallel might be all you need to get by on most situations. I suggest you look around and see if you can get used 300w sized panels in your area. $75 to $100 is a typical rated for a large used panel.

Note, I have a used 290w panel on a 12v system at our hunt shack. It has no 24/7 load. We have a 500w cheapo inverter for 120v LED lights, which is about all it is for, that and phone charging. The battery is sized to provide us with lighting over a 5 day weekend with medium solar conditions. We are in a wooded area and the panel only gets 2 or 3 hours of sun if we are lucky.

Next month I am taking 4 additional large used panels and set up a charging station for a golf cart that we plan to take with us. So fun adding that system to the camp. That system will have a 24v battery that we can charge during the day and dump to the golf cart at lunch or in the evening. We might also use it for a slow cooker during the day.

The panel has a clear view of the sun and is South facing. I found another 100 watt solar panel on FB for $129 free shipping.

 

[DThames]

$130 seems a bit expensive since you can get them for $90. I don't recall if you mentioned charger type but if you have a PWM type, you will likely need to connect them in parallel. Do you have a picture of the specs on the back of the one that you have? Is it a 12v type panel? (17-19 Voc)

 

[Nobodybusiness]

Welcome to the forum.

PWM controllers work by shorting the panel to the battery. This is most appropriate for panel matched to batteries. Your 40V panel likely performs optimally around 30V. You're forcing it down to ~14V meaning whatever the panel's actual power is, you're cutting it in half due to forcing it to run at 1/2 the voltage. If this was a 250W panel, you would never see more than about 120W out of it due to the way PWM works.

When the battery reaches absorption voltage, the unit begins connecting and disconnecting it from the battery hundreds or thousands of times a second to maintain the absorption voltage. I would expect you might see full panel voltage when it's in that mode.

If you're seeing panel voltage closer to battery when the battery voltage is lower like in the first video, and it only shows high

Deleted

 

[70oldsracer]

$130 seems a bit expensive since you can get them for $90. I don't recall if you mentioned charger type but if you have a PWM type, you will likely need to connect them in parallel. Do you have a picture of the specs on the back of the one that you have? Is it a 12v type panel? (17-19 Voc)

Here is the charge controller I have

20A 10A Epever MPPT Solar Charge Controller 12V/24V Battery Regulator Max PV 60V | eBay

Battery Temperature Sensor Epever Monitor Adapter RS485/USB Communication Cable. when the internal temperature reach 81â, the power reduction mode will be turned on. MPPT 1000W Grid Tie Inverter For 18V/36cells Solar Panel AC110V SolarEpic Power.

www.ebay.com

Unfortunately, the panel I have didn’t have a label on the back, so I’m not really sure of the specs. If you go back to the first page, there is a video of the charge controller hooked up to the panel and the batteries

 

[70oldsracer]

Just a general statement of design and there are no hard and fast numbers. But consider that at best you get less than the panels rated watts when the panel is pointed at the sun on a good day. Anytime the sun is off angle (pretty much all of the time) you get less. If the sky conditions are less than ideal, you get less. If you have any tree or structure shading you get a LOT less. With a fixed array, I stated you would be good to get 80% for 4 hours a day. In those 4 hours, I would like to charge my batteries (fully) in 3 or 4 hours. So I would want maybe 3 or 4 times the panels that I would "need" under good conditions. Consider then that if the battery was large enough to carry you through 2 or 3 days of poor conditions, on the 3rd or 4th day the sun comes out for a few hours, I want to quickly get my battery back where it can go for 2 more less than good days.

Original poster, you have not stated how clear the panel's sky view is. It needs to be free of shade. Another 100w in parallel might be all you need to get by on most situations. I suggest you look around and see if you can get used 300w sized panels in your area. $75 to $100 is a typical rated for a large used panel.

Note, I have a used 290w panel on a 12v system at our hunt shack. It has no 24/7 load. We have a 500w cheapo inverter for 120v LED lights, which is about all it is for, that and phone charging. The battery is sized to provide us with lighting over a 5 day weekend with medium solar conditions. We are in a wooded area and the panel only gets 2 or 3 hours of sun if we are lucky.

Next month I am taking 4 additional large used panels and set up a charging station for a golf cart that we plan to take with us. So fun adding that system to the camp. That system will have a 24v battery that we can charge during the day and dump to the golf cart at lunch or in the evening. We might also use it for a slow cooker during the day.

I love my golf cart. I built it a few years ago and use it all the time.

 

[Vigo]

This is NEVER recommended.

It would be a great way to break a solar controller in most cases (most inverters are used for loads way over 20w!!), but i think a small lightly loaded inverter on a fused line probably wouldn't do anything. Probably being the key word. Sort of depends on whether the inrush of the inverter's capacitors on initial hookup lasted long enough to damage anything in the controller, if it was big enough to do so in the first place. Have to consider that most 12v charging ports that people run 'car' inverters off of are fused for 10a, while this load controller and many others have load ports rated at 20a. The car port won't give a crap about 'inrush currents', but the charge controller's internals might.

You're right, too many unknowns on my end to 'recommend' it.

It would be better to hijack the on/off switch circuit, but then you're 'customizing' your inverter and some won't like it. I couldn't recommend using a relay or contactor off load ports to control the inverter power because if your total load is ~20w, just holding an N.O. relay closed 24/7 would add measurably to that number. Maybe some form of latching relay? Eh, again i lack too much info to push that idea on someone else. An NC relay would work IF you could get the 'load on/off' setpoints to both be as low as your intended cutoff voltage. Still wacky.

Glad you made me think harder.