Newb to Solar Generator Question

[chaosinwest]

I have just spent the last 4 hours reading posts and watching Youtube videos to make a portable generator. I think I understand most of how it all goes together. I get how you can use an Anderson or SAE plug through a solar controller to charge the battery. How can I use a basic electrical outlet to charge the battery at home? Is there a simple way to do that as well? My use case would be something like this: small battery generator for little ARB type fridge, recharge some devices (phone etc) when out camping and fishing. I want to be able to charge it at home, and then maintain with solar.

What am I missing? Do the solar controllers also allow you to use a plug to charge in the garage?

Any advice would be appreciated.

 

[dwh]

To charge from shore power, you have to buy a battery charger that runs on 120 volts AC.

 

[chaosinwest]

Ok, so that is separate from solar controller?

 

[dwh]

Solar charge controller takes low-voltage DC solar panel and connects it to low-voltage DC battery.

Shore/grid/house power is high-voltage AC. Battery charger takes high-voltage AC and converts it to low-voltage DC to charge a low-voltage DC battery.

So yea, totally different beast.

 

[jonyjoe101]

solar charge controllers only work with the solar panel. the 2 wires from the panel go into the controller , then 2 wires go from the controller to the battery.

Once you get home you can maintain your battery with a 2 amp trickle charger you can plug in the wall.

But you can always keep the solar panel connected to the battery even at home if its outside and leave it on 24/7. The controller will keep the battery from being overcharged. it will be like a trickle charger once the battery if full.

For a small panel all you need is a pwm solar controller (about 20 dollar) , for larger panels in the 200 watt range or bigger you need a mppt solar contoller (over 100 dollar).

The arb fridge (any danfoss compressor 12 volt fridge) will use about 27 amps in a 24 hour period when set to 40 degrees. When I had a edgestar 12 volt fridge i used a 120 watt panel and a 75 ah battery and was able to run it 24/7 and power other things. 120 watts puts out about 7 amps of power. if you plan to also use alternator/generator power you dont need such a large panel. I think 60 watts would probably be the smallest I would use.

 

[1stDeuce]

For a small panel all you need is a pwm solar controller (about 20 dollar) , for larger panels in the 200 watt range or bigger you need a mppt solar contoller (over 100 dollar).

This is VERY misleading. You do not need an MPPT controller unless you want to use high voltage panels (24 or 48V with lower voltage batteries. MPPT is a waste for almost anything less than a dedicated home solar system. Waste of money, that is. MPPT vs. PWM, you may get a few % more power out of your panels, but realistically not enough to justify the extra expense. Selling MPPT controllers to RV and small system users is making the solar industry lots of $, but it's not doing consumers any good in reality. DON'T BUY THE HYPE!!!

 

[chaosinwest]

Thanks so much for the additional info. I would like to leave it outside as much as possible. I live in Colorado and for the most part, its sunny! I was also reading some of the other posts in the FAQ and it does look like that 60 whats is the minimum to keep it going. I'll also go with PWM because its just a small little system.

Really appreciate the advice!

 

[dwh]

Over on the Northern Arizona Wind & Sun forum, the solar engineer types ran the numbers on MPPT vs. PWM in detail down to the penny. What they came up with was that MPPT doesn't pay for itself with less than 200w of solar panel. That was some years ago, but prices on MPPT controllers haven't really dropped all that much, so it's still a viable rule of thumb.

But even above 200w, the payback doesn't come quick until you start getting up into the 500w range, then yea, MPPT is certainly worth it.

Even so, MPPT can be justified for setups that are running at the bleeding edge of efficiency - if you really need a few extra watts per day out of a small solar rig, then the price might not be the most important factor in the decision.

 

[chaosinwest]

I don't think I'll need bleeding edge. In my little generator box, do I use an inline fuse attached to each port and then attach each inline to the battery post? The video I was watching on youtube had the inline fuse after the battery connection and then everything tied into that one wire. Is that what a fuse box does? Let's you connect multiple things to the box and then one connection to the post of the battery. As you can tell, I'm really new to this.

 

[dwh]

The fuse protects the wire, so you need a fuse to protect each wire.

You can connect a bunch of circuits directly to the battery with a fuse for each one, or you can run one bigger wire (with a fuse to protect it) to a fuse box and then run multiple smaller wires from the fuse box - which has fuses to protect each smaller wire.


Or, you could put one fuse at the battery - say a 20a fuse - and then connect a bunch of wires to that fuse. But each wire must be big enough to carry at least 20a. Otherwise if the wire shorts, it will melt before the fuse does.

And also, the total load of all the wires has to be less than 20a or the fuse will blow.

 

[chaosinwest]

Thank you DWH! I really appreciate the advice...