Solar Stuff...

[Wulf202]

You could piece together twice the system for half the price by sourcing each component separately.

Or some kind of car analogy.

[Fentonite]

Reviving the old solar thread. I have a tiny cabin (ok, a tuffshed) on a mining claim in the mountains. I just finished putting in an equally tiny solar power system to run multiple 12V LED lights, a fan, and a charging station for portable devices. Two marine batteries in parallel, a 30W solar panel, cheap charge controller, automotive fuse block, and a homemade switch panel. Seems to be working just fine so far for my needs, time will tell if it holds up. I really know nothing about this stuff, just winging it, so I'm sure I did some things wrong. Fun project, either way.

[Grant H.]

Doesn't look like you did anything wrong to me.

If you find yourself looking at a slightly bigger panel, look at an MPPT controller first. For a little additional cost, I saw a 25% improvement in solar production when using small 10W rated panels (went from 8 watts with a non-MPPT to 10.5 watts with the MPPT).

Some people forget that small solar installs can be just as good/beneficial as big ones. I have LED lights in my backyard shed that I did with just a small solar setup, and it's great. I didn't have to trench and pull power, and being low voltage no permit was required!

[Fentonite]

Googling "MPPT controller"...

[Grant H.]

Lol.

Sorry, Maximum Power Point Tracking Solar controllers.

Basically they hold the solar panel to a lower voltage (a 12v panel is around 18v open circuit) and convert that extra power to current instead of peak voltage. Essentially just more efficient.

[Fentonite]

Thanks - that's makes more sense than what I was finding online. So, could I use a 24V, 30A panel with my 12V setup, if I had an MPPT controller? I have a 24V panel just sitting there, could swap if it would be more efficient and not fry my batteries.

[Grant H.]

Thanks - that's makes more sense than what I was finding online. So, could I use a 24V, 30A panel with my 12V setup, if I had an MPPT controller? I have a 24V panel just sitting there, could swap if it would be more efficient and not fry my batteries.

I'm guessing you mean 24V 30W, not 30A. Otherwise that's a big damn panel...

Yes, a 24V panel can be fed into a 12V battery bank with an MPPT controller.

As far as running both into the same battery bank, yes you can, run the panels and controllers in parallel.

[Grant H.]

No need to apologize.

Happy to help. Like I said when I started this thread, I've done a lot of solar, for work and for fun, and I'm happy to share information and suggestions.

[Grant H.]

2. Solar Power solution for network gear in my house.

A friend of mine called and offered me 26 7.5AH 12VDC batteries for a great deal, since he got them as scrap when he refreshed a set of UPS's for one of his customers. They all tested at 12.3VDC or higher, so they are all good.

My plan is to move my fiber modem, router, switch, and access points to solar. The fiber network is all on emergency backups, so it all stays up/functional even when the power is out. So, if I keep all my gear powered up, I end up with internet access even with power outages.

Pointless? Sort of, but I couldn't pass up the deal on the batteries, and I don't have a better use for them right now.

So, with 26 batteries, I used 2 in the previous project, and used the other 24 for this. I wired them into 6x 48VDC cells, and will then use a collection of smaller solar panels wired into 48VDC arrays. I spotted an auction on eBay the other day for 48V specific controllers, and gave $15/ea for them, hence my 48V plan currently.

Morningstar PS-15M-48V - Used, but cheap/functional on eBay, so why not???
0518171949 by ARNEWB, on Flickr

Batteries placed into boxes temporarily, wired together to put on a trickle charger till I get it all finished...
0518171932 by ARNEWB, on Flickr
0518171937 by ARNEWB, on Flickr

The cabinets were free to me when I replaced them with metal boxes for a customer, so that's why I used two to start, but when I get them mounted in the backyard, I will condense them down and have the controller and the inverter mounted in one of them.

I'll keep this one updated as well in case people are interested.

[Fentonite]

Yes, 30W, sorry. Cool, thanks for your advice! Much appreciated.