solar cottage

[jackluminous]

I got the solar electric system installed in our cottage (we call it the Pumphouse, since on our site plan it is identified as a pumphouse, but presently it has no water anywhere near it).

Here are some pictures:

This is the cottage, viewed from the south. I put the solar panel on the roof as you can see. Our latitude is about 31 degrees and the roof angle is 45 degrees, so I'm really optimizing for winter sun. I don't know if that's what is best but I guess I'll find out. The solar panel is a 54-watt Kyocera and it really charges the batteries well.

Here is the control board. On top is a 20-amp charge controller, with a blade-type fuse on the positive line to the battery. The metal electrical box just houses the wire nut connection for the positive wire. The blue thing is a pure-sine wave inverter. I'm planning tidying this up and enclosing it in a box. We have an inquisitive toddler who will be sleeping nearby. I'd also like to install some sort of volt meter so I have a better idea how the batteries are doing without opening the box.

Here is the battery box, attached to the north side of the cottage. I'm really proud of this part. It is made from 99% recycled material or material found on hand (leftover scraps from other projects). My employer had bought new server equipment that came in a stain-grade plywood box. I took the box thinking I could make a router table out of it, but when I got bit by the solar bug there was only one thing for it: battery box!

I used scrap insulation, plywood, and cement board to convert it into a super-insulated, sealed box. It uses convection ventilation, with an air intake at the bottom of the door (screened to prevent insect or rodent entry) and a continuous ridge vent at the top. There is a lockable, hinged access door on the front and the "roof" is removable to make it easier to see how well the electrolyte is covering the plates. All surfaces inside are coated with roll-on bedliner stuff; the guy who sold me the batteries recommended it as it prevents any spilled electrolyte from eating through the box.

The batteries are 225Ah golf-cart batteries bought refurbished at $45 each. There is a 120-Amp fuse on the positive inverter cable. I think I spent $30 or less on the battery box, which was for the can of roll-on bed liner, the hasp, and the hinges for the door.

I plan to devise a way to prevent any hydrogen gas from drifting into the cottage through the opening for the cables. Probably some plastic conduit with an LB on the inside of the cottage, angled downward. I might run that conduit into a service panel with disconnects for all the lines going in or out of the battery box.

Overall I'm pretty satisfied with this system. I can charge all my cordless tools with it and still have enough power to run lights for several hours a night. Granted that's just weekend use; I couldn't do that all week. The solar panel is too small to keep up with that.

[kenputer]

Nice looking setup. I like the mounting of the batteries out side the building and you could get a car volt meter to connect to them and mount in the building to keep an eye on the voltage.

Ken

[jackluminous]

Thanks! I like the car volt meter idea.

[Ungrounded Lightning Rod]

I'd be more concerned about sulfuric acid droplets than hydrogen.

In either case:  Consider using permanent marine caulk.  It's a self-vulcanizing rubber you can get by the tube at any chandlery.  Hardens up into something the consistency of a hard rubber stopper, bonding to the wires and wood nicely.  (You can also use a temporary caulk ditto if you might want to run more wires through later.)

[ghurd]

Neat little system.

Might want to chech how much power the inverter uses when it is turned off.

Some take quite a little bit.  Not enough to notice in a larger well used system, but it could add up to considerable wasted power in 5 days.

Simple solution would be adding a heavy switch in the battery line (HF 'Battery Cut-Off Switch' #92688?).

G-

[wooferhound]

I love it.

Reminds me of my first system.

Make sure that every wire that connects to the battery, has a fuse on it.

[CmeBREW]

Nice get away! I like that metal roof you can paint it white in the summer and black in the winter.  Might want to get one of those cheap digital multi-meters at Harbor freight store for a few bucks to monitor voltage (and amps) and have it screwed next to your charge controller.  Mine have always been quite accurate on the tenth scale showing accurate 12.7 , 12.5 or whatever.

You can save some power using those 12vdc 5Watt cfl bulbs directly to the batts and skip the waste of the power inverter. I've been using the same 12v bulb now for over a year and I use just one bulb every night for about 3 or 4 hours. Practically nothing out of the batts.  I have it wired in the ceiling fan lights in the middle of the ceiling and it lights up the whole room decent enough for me.  Helps me get sleepy better. There is another one there in case I need more light.

Then you could have enough power left over to watch hours on one of those 20-25 watt 10.2" TV/DVD players hooked to your system. I watch 3-4 hours a night on mine and it takes very little out of the batts. I don't even use my big 170Watt TV/dvd anymore.

You could also make a nice DIRECT batt hook-up  2-4 watt ceiling fan in there out of a PM DC motor with High voltage/LOW amp rating. (Dc ball bearing motor something Like 90Vdc/ 1750rpm/ 2-4Amp rated)  The motor and Fan blades should go something around 260rpm or so. Just do NOT get a big AMP rated dc motor (like 7-18amp) or it will use WAY more power due to the much bigger gauge wire in the coils.

Mine takes less than 2Watts if hooked directly to a 6v golf cart battery-- or 3to4 watts hooked to 12v batts since one watt is wasted in the rheostat to slow it down a little. So 2watts x 10 hours a night is almost nothing. (Only 20 watthours out of the batts)

If you had all this stuff in there you could be 'Snug as a bug in a rug'!

Thanks for sharing the photos. Good start system.

   

[MattM]

If he is concerned with changing colors for the season he might as well run an extra skin of panels on some hinges at the ridge so he can just flip from summer to winter colors.  Painting twice a year sounds like too much work.  Hmmmm, if he could integrate a flat plate solar collector into the roof for winter heating...

[jackluminous]

The thought of a giant piano hinge along the ridge line with an extra set of steel panels made me laugh!

While I am at it I could figure out a way to make the extra panels flap in the wind and convert the resulting mechanical energy into electricity. :-)

As for winter heating, I'm hoping the south-facing windows will do the trick once I've got the walls insulated. If not, the space between the windows would be perfect for a solar collector. It won't take much to heat this little building, and it doesn't get super cold out here anyway. As it is, with only an insulated roof, it warms up by mid-morning and gets in the 70s inside by mid-afternoon. Getting heat is no problem, I just have to retain it!

[MattM]

I was just trying to be tongue in cheek.

It looks like you live in the southwestern states somewhere.  You probably get too much heat most of the year as it is.  Am I even close in my guess?

As barren as the area around it looks you have plenty of real estate for a flat plate solar collector and water trough heat retention system is you needed heat that badly.

[jackluminous]

Me, too. :-)

We're very close to Tucson, Arizona. We are fortunate to have phenomenal solar access on our property, which is mostly a south-facing hillside with few trees. The best views are to the south, too, which is bonus!