Solar and power help Plz

[bullfrog]

Bob wells used to have a chart in his solar discussion that gave general estimates of what you could run off of 100 watt solar systems and 200 watt solar systems I believe up to 600 watt systems in I believe 100 watt steps years ago so you could get an idea of what you would need to improve to run more things. If I remember right a well insulated refrigerator along with a few lights and a fan were in the 200watt to 300 watt sections. I did exactly what you are planning to do except all I ran were fans, lights and 18 volt Ryobi tool battery charger and it worked fine for about 3 years before my marine deep cycle Optima batteries started not working as well. For me Optima batteries usually last twice as long. Without some way to bulk charge everyday and then allow solar through a controller float charge to full charge every day you will have shortened your batteries life in my experience and opinion. Most 12 volt compressor refrigerators have a low voltage cut off and after losing a bunch of food or worse yet getting food poisoning a few times then having to replace an alternator and a couple batteries because you failed to fully charge batteries a few days you may come to understand my views. If your plans don't include enough solar panels or a way to bulk charge a large enough battery bank I would use the batteries strictly for the refrigerator, especially if money is tight, as you can not afford to loose food or get sick. Good luck and remember results may vary!

 

[user 423]

Do you have links to the products you have. I am just not positive I want 2 solar panels on the top of my roof, I was going to put an awning system up there..

Why are you upgrading your controller? why does not other other one not do what you want?
do you have a link for the continuous solenoid?

Only one of the panels (the 100W) is on the roof. It was included in a Renogy 100W kit that I bought several years ago:

https://www.amazon.com/Renogy-Monoc...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

The 80W panel I bought separately and used as a portable. It was stored in a large cargo box I carry on the back of the van. Portables are more versatile as far as positioning them to catch the sun but sometimes are a hassle to deal with. This year I've bought a pair of tilt brackets and will mount the 80W on the top of the box and just leave it.

Even though I seemingly had good charging with the PWM controller, I decided to upgrade after reading more about MPPT controllers and because of advice given by more experienced folks here on the forum. Here's the one I bought:

https://www.amazon.com/Renogy-Charg...TAB5/ref=dp_prsubs_1?pd_rd_i=B01MRWTAB5&psc=1

The solenoid I got is rated at 65 amps but they have higher rated ones also:

https://www.amazon.com/Cole-Hersee-24059-BP-Insulated-Continuous/dp/B0064MX7US

There are also more expensive solid-state switches offered by Blue Sea,etc. that do the job.

PS: I have an older 19" LED TV that is powered by 12 volts through an AC adapter. I will be wiring this directly, eliminating the need to use an inverter.

 

[AuricTech]

I have the DOKIO folding solar panel to which the original poster linked. It's pretty good for how I use it, which is keeping a 299Wh LiFeP04 power station charged so I can run my laptop and USB-powered devices while I'm tent camping for a couple of days. In that role, or as a lightweight extra panel for boondocking, I think it's worth the price premium. That being said, you're better off finding a rigid panel for a permanent installation. Rigid panels are both less expensive and more rugged than this DOKIO folding panel.

 

[Scott3569]

Forgot about my fans, I will be using a set up with computer case fans each of them are 1 A

 

[Scott3569]

Only one of the panels (the 100W) is on the roof. It was included in a Renogy 100W kit that I bought several years ago:

https://www.amazon.com/Renogy-Monoc...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

The 80W panel I bought separately and used as a portable. It was stored in a large cargo box I carry on the back of the van. Portables are more versatile as far as positioning them to catch the sun but sometimes are a hassle to deal with. This year I've bought a pair of tilt brackets and will mount the 80W on the top of the box and just leave it.

Even though I seemingly had good charging with the PWM controller, I decided to upgrade after reading more about MPPT controllers and because of advice given by more experienced folks here on the forum. Here's the one I bought:

https://www.amazon.com/Renogy-Charg...TAB5/ref=dp_prsubs_1?pd_rd_i=B01MRWTAB5&psc=1

The solenoid I got is rated at 65 amps but they have higher rated ones also:

https://www.amazon.com/Cole-Hersee-24059-BP-Insulated-Continuous/dp/B0064MX7US

There are also more expensive solid-state switches offered by Blue Sea,etc. that do the job.

PS: I have an older 19" LED TV that is powered by 12 volts through an AC adapter. I will be wiring this directly, eliminating the need to use an inverter.

in my research I read that your solenoid should match your Alternator.. would you agree with that?

 

[MrAlvinDude]

Did you come across the formular that says:

Volt x Ampere = Watt


If you can convert the power used (or stored) to watts, then it might get easier for you to evaluate things yourself.


For instance, with a 12V (AGM) lead acid 100Ah battery (where you only use 50% of the energy = max50Ah used) the calculation is:

12V x 50Ah = 600Wh


With a "100W" solar panel, you might be able to get 50-80W an hour, most of the time. 

So a guess would be between
(600Wh / 80W =  7.5 hours) 
to
( 600Wh / 50W = 12 hours)

--- 

Using watt numbers it may also be possible to guesstimate on which days you will be able to power your fridge on solar only.

It has previously been guesstimated that it uses about 22.5ah (at 12V). expressed in watt, this is

(Volt x Ampere = Watt)
12V x 22.5Ah = 270Wh

So during a day (of sun) you need to accumulate about 270W, for your fridge to run for one 24 hour period. 


270Wh / 80W = 3.375 hours
to 
270Wh / 50W = 5.4 hours

So 3 to 6 hours of okay sun will keep your fridge running.

--- 

Does it help you any, to try to convert/express things in Watts? 


And do you think that you can use the 

Volt x Ampere = Watt

calculation, to convert your practical  numbers to watts, now?

 

[user 423]

in my research I read that your solenoid should match your Alternator.. would you agree with that?

I probably should have gone with a stouter one but then you read so much about how alternators never put out as much as what the specs say. Much like PV panels.  If it fails prematurely, it's no big deal to replace.

The controller I have lets me keep a pretty good eye on what condition the battery is in. With my level of usage along with how much driving I will be doing, I'm figuring that the battery will never get drawn down so much as to need max output from the alternator.

For the past couple of years this has been an experiment for me balancing costs vs. results. I'm still in a learning curve with it and it's interesting. YMMV

 

[MrAlvinDude]

Another example of watts, is about a cell phone.

The battery in a cell phone is often around 3000 to 4000 mAh  (milli Ampere hours).
milli is 1/1000
So 3000mAh = 3Ah


The voltage of such a battery is about 3.7V


So the watts stored in a cell phone is something like:

(Volt x Ampere = Watt)
3.7V x 3Ah = 11.1Wh

Because of voltage conversion losses, lets guestimate that about 15W of solar is needed, to charge a cellphone.

 

[jacqueg]

It certainly does sound similar to what I am aiming for.. Do you have links to the products you have. I am just not positive I want 2 solar panels on the top of my roof, I was going to put an awning system up there.. and I would have two of the same batteries..  

Why are you upgrading your controller? why does not other other one not do what you want?
do you have a link for the continuous solenoid?

You can cover your entire roof with solar panels, and still have an awning. If you mount the panels on a roof rack or Z brackets, you can easily attach your awning as well. Won't be automatic though.

 

[Scott3569]

Did you come across the formular that says:

Volt x Ampere = Watt


If you can convert the power used (or stored) to watts, then it might get easier for you to evaluate things yourself.


For instance, with a 12V (AGM) lead acid 100Ah battery (where you only use 50% of the energy = max50Ah used) the calculation is:

12V x 50Ah = 600Wh


With a "100W" solar panel, you might be able to get 50-80W an hour, most of the time. 

So a guess would be between
(600Wh / 80W =  7.5 hours) 
to
( 600Wh / 50W = 12 hours)

--- 

Using watt numbers it may also be possible to guesstimate on which days you will be able to power your fridge on solar only.

It has previously been guesstimated that it uses about 22.5ah (at 12V). expressed in watt, this is

(Volt x Ampere = Watt)
12V x 22.5Ah = 270Wh

So during a day (of sun) you need to accumulate about 270W, for your fridge to run for one 24 hour period. 


270Wh / 80W = 3.375 hours
to 
270Wh / 50W = 5.4 hours

So 3 to 6 hours of okay sun will keep your fridge running.

--- 

Does it help you any, to try to convert/express things in Watts? 


And do you think that you can use the 

Volt x Ampere = Watt

calculation, to convert your practical  numbers to watts, now?

That does help, and certainly makes more since to me.. I appreciate the explaination

 

[Scott3569]

You can cover your entire roof with solar panels, and still have an awning. If you mount the panels on a roof rack or Z brackets, you can easily attach your awning as well. Won't be automatic though.

No not planning on an automatic system for that.. and your right I can redesign.. especially since most of my design is in my head and really only theory at the moment, I have made some chicken scratches.

 

[jimindenver]

The last thing I would ever suggest is attaching anything to the mounts that hold your solar panels on.

 

[PlethoraOfGuns]

Electricity can be a complicated force to understand. Volts? Amps? Ohms? Volts is the force to push the amps past the resistance(ohms) of the wire. Amps and watts are similar, both being a measure of the power being consumed. But amps can change depending on the voltage. Watts will stay the same over different voltages. Keep in mind that most solar panels will run at 18+ volts. The charge controller steps that down to 12 volts to charge the batteries. How a charge controller does that is the difference between a cheaper PWM controller and a more expensive MPPT controller.

 

[thegoodtom1]

Also, look for a 12volt dc television. There are lots out there.