Help, first venture into solar

[kgs499]

Hi everyone, I've been reading in here for a few months now as I am in the process of creating a "portable solar power supply". Every year I go out to this 18 day festival and they don't allow generators as it would be entirely too loud. So I decided that I've always been interested in solar so I want to see what I can do with it.

Anyway the system is rather small and designed to be cheap. One day (when funds become more available) I'd like to make it bigger and better.

But here is my system:
Soalr power set up.jpg


Basically: 100w solar panel connected to 20a charge controller loaded with a <5 amp fan and attached to a 55ah battery that runs to a 400w inverter

Here are my questions..

1. Is there anything that screams "This is not going to work"? I'm pretty sure there isn't, also all I am doing is powering about 6 strings of led christmas lights for soft lighting outdoors

2. Everything I read also discusses fuses. Do I need fuses in this system? Where? And what kind? I know almost nothing about electricity so as much information as possible is educational!

3. All the parts, except of course the panel, will be inside a 3/4 in birch wooden box that measures 1.5x1x1ft will I have problems with things heating up too much? I planned on putting slits on one side and a fan blowing on the inverter as I know those tend to warm up.

Any information is highly appreciated!

Thanks

-Kevin

[inetdog]

Hi everyone, I've been reading in here for a few months now as I am in the process of creating a "portable solar power supply". Every year I go out to this 18 day festival and they don't allow generators as it would be entirely too loud. So I decided that I've always been interested in solar so I want to see what I can do with it.

Anyway the system is rather small and designed to be cheap. One day (when funds become more available) I'd like to make it bigger and better.

But here is my system:
[ATTACH=CONFIG]4074[/ATTACH]


Basically: 100w solar panel connected to 20a charge controller loaded with a <5 amp fan and attached to a 55ah battery that runs to a 400w inverter

Here are my questions..

1. Is there anything that screams "This is not going to work"? I'm pretty sure there isn't, also all I am doing is powering about 6 strings of led christmas lights for soft lighting outdoors

2. Everything I read also discusses fuses. Do I need fuses in this system? Where? And what kind? I know almost nothing about electricity so as much information as possible is educational!

3. All the parts, except of course the panel, will be inside a 3/4 in birch wooden box that measures 1.5x1x1ft will I have problems with things heating up too much? I planned on putting slits on one side and a fan blowing on the inverter as I know those tend to warm up.

Any information is highly appreciated!

Thanks

-Kevin

Hello Kevin and welcome to Solar Panel Talk!

Rather than go over all of the material from the beginning, I suggest that you start out with the Solar Monolith project by Mike90250, one of our moderators.
His home page is here.
Unfortunately both the Facebook and the Alternative Energy Zone links about the Monolith from those pages seem to be defunct, so I am not sure what would be the best way to get details.

What you will have to reconcile yourself to is that unless you spend big bucks on a Lithium chemistry battery system you will either have to ramp your expectations down or your size and weight limit up.

And yes, fuses are a critical part. Even a smallish (car sized) battery can put out enough current to start a fire or burn you badly if something goes wrong.

[kgs499]

Not an issue

Well lucky my idea of "luggable" is different. I take out 2 10x20 canopies, multiple boxes of metal poles, multiple tents, anyhow you probably get the idea. The sucker is staying out there for a while and I only have to take it out once and bring it back once. I sized the box by the size of the components I am putting inside of it. The weight doesn't matter at all. All I am doing with it is powering 6 strings of led christmas lights for about 4-6 hours a night, more likely 4. As far as I know with just 1 55ah battery the whole thing will weight around 100lbs.

I already purchased the panel.

If I need fuses I guess I would need one going from the battery to the inverter and that would be a 400/12v =~= 33amps at maximum so could a 30a fuse work? I don't plan on trying to run all 400w off the cheap thing.

Any more thoughts? My plan is to kind of learn while going and make my own design and enjoy myself.

[inetdog]

If I need fuses I guess I would need one going from the battery to the inverter and that would be a 400/12v =~= 33amps at maximum so could a 30a fuse work? I don't plan on trying to run all 400w off the cheap thing.

Any more thoughts? My plan is to kind of learn while going and make my own design and enjoy myself.

The most critical fuse is one right at the battery isolating it from both the inverter and the charge controller wiring.
Some popular fuse holder combinations which mount right on the battery post are made by Blue Sea. (www.bluesea.com)
The CC can produce only a limited amount of output, based on the panel power, so a fuse there is really to protect the CC in case of a failure rather than to protect the battery and wiring.
A fuse built into the inverter will still not protect the interconnecting wiring from current flowing from the battery in case of a wiring fault.

400/12v =~= 33amps at maximum so could a 30a fuse work?

Well, to be conservative, the inverter will (try to) work down to a battery voltage as low as 10 volts, so 400/10v = 40A. And that does not take into consideration any surge loads on the inverter.

If you really keep the loads on the inverter down to 200W or less, a 30A fuse will probably be OK. But carry spares.

[kgs499]

That makes good sense. I've never quite understood how to connect the inverter to the battery without having it connected to the same wires that are charging the battery. Won't the inverter be using some amount of electricity that is being given to the battery from the CC? I guess if it isn't on.. I think i'll go with a 40a fuse would it be better to split the wire and just wire it in the middle (I'm staying cheap here).

If I understand this correctly I want 1 40a fuse (I'll bring some extras) between the battery and the inverter (on the positive wire?) and a 15a fuse between the Charge controller and the battery.

Also I'm planning on attaching something like this: voltage meter just for fun and as a nice display of my charge. Basically the electral output of my system is not a big deal since I'll be power 6 strings of 6w christmas lights which puts my total per hour usage at 360wh if I had them on for 10 hours which means I would only need about 4 - 5 hours of sunlight to charge my battery back. My only issue is with the wiring of the whole thing. But I'm slowly getting it. I've got about 3 weeks to get my act together.

[Sunking]

Won't the inverter be using some amount of electricity that is being given to the battery from the CC? I guess if it isn't on..

Power goes wherever it is being demanded. For example let's say the battery is fully charged up, it is noon and the inverter is demanding 50 amps on a 12 volt 400 watt solar system. The panels will provide roughly 30 amps, and the battery supplies 20 amps.

I think i'll go with a 40a fuse would it be better to split the wire and just wire it in the middle (I'm staying cheap here).

Good way to start a fire. The fuses go directly onto the battery term post. You will need a minimum of 4. 2 on each polarity going to CC, and another two on each polarity going to inverter or distribution panel.