Solar Kit - Is this a good thing?

[RV-Hopeful]

Amazon has a solar kit

Renogy 1-- Watt 12 v Mono with 30A PWM controller - lcd display
assorted connectors
z brackets

This battery and the power inverted were "frequently bought" with the above.

35AH 12V dc deepcycle sla solar energy storage battery.  Will that battery be a good one? 

Bestek 400W power inverter DC 12V to AC 110V car adapter with 5A 4 USB charging ports.

I currently have these items in my amazon basket and have yet to pull the trigger on buying as I'm oh so confused about solar.  If I have all the parts I'm sure I can get it together, but I'm not sure what parts I need! Thanks in advance!!!! Can't wait for the RTR
Thanks.

 

[CautionToTheWind]

This CRVL blog post might help (solar basics): http://www.cheaprvliving.com/basics-solar-power/

 

[RV-Hopeful]

This CRVL blog post might help (solar basics): http://www.cheaprvliving.com/basics-solar-power/

Sadly I've read many things (that included) as well as watched a gazillion videos and my eyes glaze over and my brain sizzles.

I'll give it another shot tho. thanks!

 

[MrAlvinDude]

What you have described to have in your basket is a very basic system and it will get you started.  
It will allow you to do your the very basics, like charge your laptop, cell-phone, power your interior lights,  and stuff like that.

When it comes to solar, the advice is always: get as much as you can afford.  So if this is what feels like being affordable to you, then it will indeed get you started. 

You might consider also getting a 40A (40 amp) fuse and fuse holder. It is ALWAYS a good idea to have a fuse very close to the positive pole of the battery.
Could be one like this: 
https://www.amazon.com/Jex-Electronics-Line-Holder-Waterproof/dp/B01AKDHPMC



Anything in particular you have doubts about?

Like are the parts a good size or a good match? Yes they are. You might however consider a slightly larger battery, if you can afford it.  

As you should never use more than 50% of the power available in a lead acid battery, you can fully recharge a 35Ah battery with a 100W solar panel (in perfect sun) in less than 3 hours. 


But again; Anything in particular you have doubts about?
What are your biggest concerns or questions, when it comes to solar?

 

[RV-Hopeful]

[quote pid='351081' dateline='1511395823']
Thanks so much for asking specific questions ... I'm so lost in this that I appreciate it greatly.

Anything in particular you have doubts about?

Like are the parts a good size or a good match? Yes they are. You might however consider a slightly larger battery, if you can afford it.  Eventually I want to grow to 400 Watts - can I buy a battery now that would support the 100W and grow with the 400 W expansion or do you have to have a battery per 100W panel?  As an example:  If I spend $100 on a battery for 100W but could spent $250 for battery to support 400 W then I'd be more inclined to spend more now as essentially I'd save money in the long run.

As you should never use more than 50% of the power available in a lead acid battery, you can fully recharge a 35Ah battery with a 100W solar panel (in perfect sun) in less than 3 hours. What size battery would you recommend for 100W if that's all I do right now?  Or for a 400W growth if that's possible.

But again; Anything in particular you have doubts about? 
What are your biggest concerns or questions, when it comes to solar? I hear fuses are important, I would imagine there are guidelines as to where these go ... I haven't a clue. 

Part of me is like ... "just get the stuff, do you best and perhaps someone at the RTR will help correct my mistakes (chuckle)" ps - I'm doing this via credit cards so while money is an issue I still have some leeway ...
[/quote]

 

[MrAlvinDude]

Okay. What I hear is; that you want to start affordable, but would like to make wise choices, so it also becomes cost effective to one day grow from a 100W to a 400W  solar system.

hmmm.... how to start with an affordable 100W system and possibly grow that into a 400W system?

I see two paths for this:
a) start with a 100W system, and sell it when you upgrade
b) start with components that works well for the 100W system, and plan an upgrade path, where as much as possible can be used along the upgrade path.


For upgrading I see two paths;

one path where the upgrade is to start with one 100W panel, and then later add one, and one and one, to eventually end with four similar panels. 

another path can be, to start with a kit, and later add another kit, so there are two types of panels and two types of solar charge controllers. And possibly two sets of batteries, though one large battery bank will be easier to manage.


To get a good idea of what would be the most cost effective path (of the three listed), it might be prudent to examine each type of components, like The panels, the solar charge controller, the wires and fuses, the battery / battery bank. 


No wonder you feel confused, as this analysis will not be a simple one.
I do however hope it will lead us to some simple solutions, with only a few steps in the solution, so you can start out with 100W and move up to 400W at a later time.

 

[MrAlvinDude]

First question might be: can a 100W starter kit be used to carry you all the way up to a 400W solution?

Answer: Not very likely, as kit components are typically chosen as a good compromise to fit together as just that kit, and for the company to still make good money on the kit.

Can a 100W kit however be used as the first step, so it becomes a 200W kit?
Answer: yes, some kits are very likely to be able to do that.


Could I later expand, so I have two kits of 200W and in total have 400W of solar?
Yes, that might be quite doable. Though the solar charge controllers with kits are not typical the best suited for use in dual controller configurations, as they are typically not very configurable. And a with a dual controller system, it is best if the controller is configurable, so they do not end up "fighting" with each other. 



Is it possible to use the same battery all the way from a 100W  system to a 400W system?  
Not likely. 

A quick search on amazon reveals the followiing:

This is the cheapest 100Ah deep cycle battery I could find on amazon ($165) ($1.65 per Ah) 
https://www.amazon.com/Universal-UB121000-45978-100AH-Cycle-Battery/dp/B00S1RT58C


aparently amazon do not carry 400Ah deep cycle batteries

So this was the cheapest 200Ah battery on amazon  ($360)  ($1.8 per Ah)
https://www.amazon.com/NPP-Rechargeable-Sealed-Battery-Terminals/dp/B01J94RBDG

I am not sure that amazon is the best place to get batteries for RV use, meaning batteries in the 100Ah to 400Ah range. 


Next question about batteries: 
Will a 100Ah battery be usable for both a 100W and a 200W system? 
Yes, that is doable.  

A 100W system can (with full sun) charge a 100Ah battery from 50% charge to "fully charged" in 6-7 hours. 
A 200W system can (with full sun) charge a 100Ah battery from 50% charge to "fully charged" in 3-4 hours.


Note: "Fully charged" for a lead acid battery is not an easy term to work with, as it most likely takes the same time to get from 50% charge, to 80% and then again from 80% charge to 95% charge and then again from 95% charge to 100% charge.
So in  this context I use "fully charge" to mean what most people most likely do to their batteries in every day use.
Until they become familiar with living in a van, and are then able to better relate to how to work battery knowledge into their daily routine, and thus become better at nusring their batteries, so they will both serve them better and do so for many years. 

So for now, lets us just use the term "fully charged" a little loosely, as one novice to another. okay?

 

[John61CT]

You want all the batteries in a bank to be the same age from the beginning, not add new ones later on.

Having a huge bank relative to solar charging capacity is no problem, as long as you don't draw more than you put in each day.

You want to try to get the bank full to 100% at least a few times per week.

Access to mains power helps.

See this also https://vanlivingforum.com/showthread.php?pid=351006#pid351006

 

[John61CT]

You can always re-use and expand on the panels, but the controllers you'll likely outgrow and replace with better ones as the system grows.

 

[MrAlvinDude]

Next path to consider:

can I buy a 100W panel, and a 400W solar charge controller, and later add one, and one and one 100W panel?

And can I add batteries to the one I already have?



First, about the panels: 

Similar panels work best together. It is possible to use different panels, so long as they have similar data, like provide the same Volt and Amp, but is just simpler and easier to make them function optimally if they are the same type of panels. 

I would expect that choosing a good name brand panel, gives you the best path to, later down the road, be able to buy another similar panel. 
Renogy is probable a very good choice then. 
If you have the time, you could possibly call Renogy and ask them two things: 
- is the particular panel you are looking at, likely to be available for some time forward, as you would like to add more panels in the next year or so?
- or what 100W panel might they recommend, if you want to add more of the similar panel within the next year or two? 

Would it be do-able for you to call Renogy, to ask those specific questions? 



Secondly, about the batteries: 

In general. batteries of similar age and similar capacity work best together. Otherwise the weakest battery sets the bar, and pulls down the stronger/newer/better battery. 

It is however possible to add more batteries to the first one, if done within, lets say, the first year or so, if the first battery is still in good condition.  But it is NOT the recommended way to go, as you might end up having the old battery make life too hard on the new battery (batteries) and that would simply be wasteful.


What if I start out with a 400Ah battery? Can a 400Ah battery still be charged by a a 100W solar panel? 
Yes it can. But it will take quite some time. 

What if I only use the 400Ah battery to the same extend that I would use a 100Ah battery, would it still take longer to charge a 400Ah battery than a 100Ah battery? 
No, as only the part of the battery that is used, will ever be/need to be recharged. So if you only use 100Ah of a 400Ah battery, then it will take about the same time to "fully charge" both a 400Ah and a 100Ah battery. 

Note: once we get into the nitty gritty of what "fully charged" actually means, then there might be some differences. But for, where we generalize (and simplify), then any battery that is missing 100Ah (or 50Ah or 30Ah) will basically take the same time to be be "fully charged" again. 



Thirdly, about the charge controller

The charge controller that comes with a 100W starter kit, is typically NOT suitable to be used when expanding all the way up to a 400W system.  These small charge controllers typically use a PWM method, and that is not optimal when being used on a 400W system. 

On a 400W system it will be much better to use a charge controller that uses the MPPT method to manage the charging.
The MPPT method is also optimal for a 100W system, but they are slightly more expensive to make than the PWM controllers, and starter systems often compete on price, so starter systems often end up having a controller that uses the PWM method. 

Also the cheapest controllers have barely any configurable settings. At most they can be set for battery type, but not for any particular voltage for the different charge phases, or to optimally suit data on your particular battery. And on a 400Ah battery, you will want to be able to get as much juice in there as fast as possible, and thus you will want to be able to optimize on those detailed parameters in the charge controller. 


A 40 Amp,  12V, MPPT charge controller can handle 400W of solar panels. With the panels connected in parallel. 



So, is the four step approach from 100W to 400W,  with adding one 100W panel at a time, and a MPPT 400W charge controller and starting out with a 100Ah hour battery a viable option? 

Well at least we will know more when we have added up the numbers.
And it will be fairly easy to do so, as we have limited the number of variables that go into this particular path, by seperating out other variable to only be included in the other path options. 


So for this path we mainly need to know about
- how likely it is to be able to get similar panels over the next year or two
- the prize of a good 400W MPPT charge controller
- if we will want to start out with a 100Ah or a 400Ah battery (I reckomend starting out with a 100Ah battery)

 

[RV-Hopeful]

Great info Mr AlvinDude, for me it honestly cleared a few things up for me. Thanks so much. I'll probably go to batteries plus once I decide between 100 w and 200 w panels to see what they would recommend ... I feel I'm being too far sighted. Like what if I put all this money into living in my van and then don't like it.  There was a time I'd jump without looking but now not so much. Limited resources and the desire to maximize those always gets me in my head.

 

[RV-Hopeful]

A link to the kit on Amazon so we are all on the same page?

You haven't stated what you intend to power with this or a future system. That should be the starting point. Also, what vehicle will it be mounted to. 1990 Chevy g20 van

If you go to Amazon through the link on the right side of Bob's home page (cheaprvliving.com) he will make a little income at no cost to you. I believe I did that, but I'll clear it out and reselect to make sure!

Guy

 

[MrAlvinDude]

So, back to asking questions.

Has the information so far made any sense to you?

Is it nice to hear that it is actually not a simple task to do, or an easy balance to find, of deciding on how to grow a solar system?

Does it feel helpful that there has been listed a few different paths of how one might practically grow a solar system?

Any one of the paths that sound most manageable to you?

 

[RV-Hopeful]

So, back to asking questions.

Has the information so far made any sense to you? Yes it has

Is it nice to hear that it is actually not a simple task to do, or an easy balance to find, of deciding on how to grow a solar system? Yes, it's nice to know I wasn't just being thick headed!

Does it feel helpful that there has been listed a few different paths of how one might practically grow a solar system? Most definitely ... Narrowing down the options totally helped. I believe I'm going with a 200 watt system to start. I'll get the appropriate AGM battery from batteries plus as they may have some knowledge of size.

Any one of the paths that sound most manageable to you? 

 

[MrAlvinDude]

A short note on the placing of a main fuse close to the battery.

Batteries pack quite a bit of energy, and in the case of a short circuit, wires can heat up if too much energy passes through them. Wires connected to car battery can even heat up to the extend where the heat from the wires can very easily make things catch fire.

This runaway-over-heating situation can easily be prevented, by placing a fuse close to the battery.  If anything short circuits, then the first thing that will heat up and become too warm, is the fuse. When the fuse is melted ("blown"), then the circuit is broken. And the energy is back to being contained in the battery.

In other words,  in order to prevent fires, because of over heating in the wires, fuses are added, as close to the energy source as possible, as close to the battery as possible.


What size fuse to use then?
This depends on the thickness of wire that is meant to be kept from overheating.  

There are tables listing thickness of wire, and how many amp they can take, before they start to over heat.

If a wire is good for 10 amp, then the fuse should be 10 amp (or less is also okay), and the wire will not overheat, even if there is a short circuit somewhere.


The wire going from the battery to the fuse, is NOT protected, so we try to make that section of wire as short as practically possible, and try to make sure that no  sharp or varm objects can damage the plastic protection of that short stretch of wire, the stretch between the battery and the fuse.

 

[highdesertranger]

you are working backwards,

1. figure out your daily usage of electricity(add up everything that you use in a day)
2. size your battery(s) to your daily usage(remember the 50% rule)
3. size your solar panels to your battery bank.

if you do it this way you will be a happy camper. highdesertranger

 

[RV-Hopeful]

you are working backwards,. My claim to fame!

1.  figure out your daily usage of electricity(add up everything that you use in a day)
2.  size your battery(s) to your daily usage(remember the 50% rule)
3.  size your solar panels to your battery bank.

if you do it this way you will be a happy camper.  highdesertranger

That's the part that messes with my head. I want to use whatever I want to use (within reason) and is practical within living in a van. My immediate needs will be minor but down the road may be larger.

 

[RV-Hopeful]

The 200 watt I'm looking at comes with mono pwm controller, can I upgrade that to an mppt later?
https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Bundle

So re battery for a 200 watt system, I'd need a 200ah battery?

 

[RV-Hopeful]

you are working backwards,

1.  figure out your daily usage of electricity(add up everything that you use in a day)

I plan on doing this in the morning. Perhaps I can get by with much less than I think!

 

[MrAlvinDude]

The 200 watt I'm looking at comes with mono pwm controller, can I upgrade that to an mppt later? Yes. 
https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Bundle

So re battery for a 200 watt system, I'd need a 200ah battery? Yes, that is the recommended size.

Glad to hear that you have found a solution path that you are happy with  :shy:

I so like that good feeling of clarity when a solutions makes sense.