My current project (solar)

[div]

Just thought some of you might be interested. My current project is installing 600 watts of soar panels on my travel trailer.
I boondock pretty heavily during deer season with the camper and last year I installed 4 6v golf cart batteries to keep it running without using the generator all the time. This year I'm going to try to leave the generator at home.
600w should be enough to keep the 440ah battery bank topped off while using the ducted furnace and tank heaters even in freezing weather. The battery bank would last right at a week from actual usage last year - with the solar I should be good indefinitely (or until I run out of propane)

Pics so far:

power center installed



Panel testing

[greenego]

Nice let us know how it works out.

[Omega]

How about expanding this post a bit, what are the pieces you have on your power center (label them), what type of panels are these, and maybe cost if you don't mind. I contemplated getting one of those harbor freight solar panel kits but am skeptical on how long they would last or how effective they are. Right now I rely on propane which runs my fridge, stove and gas lamp which warms my little hunting trailer just fine. I recently got a 3k generator/welder which I may use this year if I need anything electrical but so far the only thing I needed was maybe a fan when it was a warm fall.

[peejman]

Keep in mind that solar panel efficiency will be at its worst through hunting season... sun angle, cloud cover, etc.  I'd also watch the temp on that heat sink carefully and consider adding some heat shielding to the floor above the power center. 

 

That said, near 20A output at 15V is pretty impressive.  That should be plenty of juice. 

[Grand Torino]

Keep us posted. I don't have a clue how to do any of that but it's something I wouldn't mind learning.

[Someotherguy]

Very nice setup, thanks for posting :)

[div]

OK, let me back up a bit and see if I can answer some of the questions while outlining the rest of the system.

The battery bank, four 220ah 6v golf cart batteries wired series-parallel to provide 440ah @12v. Mounted in an aluminum treadplate box on the tongue of the trailer. Wired with 1/0g wire.


Battery monitor. Tri-metric 2025. Mounted inside the camper. This is vital to monitoring the system and is how I determined what my needs were off actual usage over the last year. (This pic was right after I connected the panels for a test and is showing 25.8 amps going into the batteries at the time.)

 

 

Power Center (clockwise from top left in the original post photo):

60amp ANL fuse going to the solar+

Marine on/off switch for solar

Morningstar TriStar MPPT 60 Charge Controller

Marine on/off switch for battery bank

250amp ANL fuse to battery bank

60amp ANL fuse to camper power center

500v Shunt (left side is to the battery -, right side is to the frame ground, Tristar ground, and solar -)

 

The panels are two 300w Renogy Polycrystaline panels.

 

The system is capable (on paper) of putting out 40+ amps. The panels are ~36v nominal @ ~8amps max each, so a MPPT controller is required to lower the volatage while increasing the amp output. You can see from the test screenshot that they were putting out 30v @ 10a during the test laying in my driveway.

When I sized the system, based off my real world usage of 40-60ah per day while below freezing outside running the furnace, lights (all converted to LED), and tank heaters I needed ~720 watt hours to recharge the batteries on a daily basis. In the winter the general consensus is that you can only get ~4 solar hours per day on average in this part of the country (4 total hours of usable solar energy) which meant i needed 180w minimum of solar output. However, on rainy/cloudy days my output will be lower, and if i only had 180w i would never be able to make up for those days. So i doubled the output and said I needed 400w. As has already been mentioned, if you lay the panels flat instead of tilting them towards the sun you can lose ~30% of your output. 600w * 70% = 420w. These will be mounted flat on the roof of the camper (hopefully this weekend). I will be mounting them so that they can tilt, but i didn't want to count on it.

 

I guess i'll find out how well i planned this winter.

Edited September 18, 2014 by div

[oldogy]

Interesting, indeed.  I like the idea.  Wish you sun filled days.

[div]

Keep in mind that solar panel efficiency will be at its worst through hunting season... sun angle, cloud cover, etc.  I'd also watch the temp on that heat sink carefully and consider adding some heat shielding to the floor above the power center. 

 

That said, near 20A output at 15V is pretty impressive.  That should be plenty of juice. 

 

The controller has built in temp-monitoring. If the heatsink temp gets too high it tapers back the current until the temp is back within range. Having said that the controller is rated for 800 watts on a 12v battery system and 3200 watts on a 48v system (~60 amps, either way) - at my theoretical max of 40 amps i've got some overhead.

 

And I think i covered the solar efficiency above in my second post. But both points are very valid concerns and things anyone thinking about setting up a system should consider.

[div]

How about expanding this post a bit, what are the pieces you have on your power center (label them), what type of panels are these, and maybe cost if you don't mind. I contemplated getting one of those harbor freight solar panel kits but am skeptical on how long they would last or how effective they are. Right now I rely on propane which runs my fridge, stove and gas lamp which warms my little hunting trailer just fine. I recently got a 3k generator/welder which I may use this year if I need anything electrical but so far the only thing I needed was maybe a fan when it was a warm fall.

 

Parts list in my second post. Let me know if you want more detail/specifics of what and why.

 

Total cost, including batteries, wire, etc... I think I'm probably in for close to $2500. My system is overkill for most folks though - mostly due to the tank heaters in the camper and my desire to leave them on. Last year i didn't make it out one weekend, during the cold snap when we got ice, due to work and the tank heaters killed the battery bank entirely. Got back after being gone 2 weeks and the water lines had frozen. I was lucky that there was minimal damage.

 

The first step to doing this is really figuring out ust how much power you actually use and need.

 

I looked at the harbor freight / northern tool panels. The two Renogy panels I bought were $750 after shipping (freight - they are 7'x3.5' and weigh 50lbs each). That's $1.25 a watt. The controller was another $500, which pushes the combo to ~$2 a watt. The harbor freight kits run $200 for a 45 watt kit - $4.44 a watt. You can do a lot better - you can get a cheap renogy kit with a 100w panel and a (not very good quality) controller with mounts, cabling, and free shipping off amazon for $190.

[Chazmr]

Very interesting.  Definitely keep us posted and show any photos as you can.  Looks like a well thought out and planned project.

[Omega]

Probably way more than I'll need, but very informative for sure. Let us know how it works this season.

[div]

Updates:

3x5 aluminum angle cut to 6inch lengths for mounting feet.


Drilling holes in the feet for bolting to the solar frame rail (2x2 aluminum angle) and for screwing into the rv roof.


Completed frame rail with mounts.


Everything bolted up, screwed down (4 #10 screws per mount, 8 mounts. RV ProFlex under and around each mount, as well as in each screw hole. Will go back with Dicor lap sealant in 48 hours and seal all edges with it as well)



Everything is plugged up and wired in now. Didn't get finished wiring until after dark so no testing yesterday. Battery bank was down to 75% so I should get a good test across the day today. I'll post up logged data in the next day or so to show real world performance.

[kckndrgn]

Great info,  Look forward to more posts on your setup.

[peejman]

Nice hat.  :)

[Clod Stomper]

Nice hat.  :)

 

I must be as blind as I am deaf.

[Peace]

wow.  -love to heat how this works out for you.

[div]

Well, a silly mistake made getting real world data take a bit longer than I wanted. Laptop fell asleep when it was supposed to be logging and I lost an entire days worth of data.

Tuesday evening at dusk I had a fully charged battery bank. I applied a constant load of 5.5 amps to the system to simulate worst case unattended scenario, and started logging. 12 hours later I had pulled 15% off of the battery bank - 66 amp hours. I left the load on and went to work to see how well the solar would cope with recharging the bank while still handling the load.

At 7pm when i checked, the batteries showed 100%. Where the camper is now, the array is in the shade from an oak until noon and has full sun exposure from then until sunset.
The meter shows the array put 130 amp hours into the batteries, or approximately 1900 watt hours. Peak current flowing into the batteries was 25.8 amps. That's 63% of the theoretical max, so I lost 7% more than the original assumption of 30% for having the panels flat. As the sun shifts lower in the sky as winter progresses that number will get worse, but as temps decrease panel efficiency increases so I'm hoping they will cancel out. I'll also have the trailer located for maximum sun exposure and minimal shading.

[div]

Nice hat. :)

Thanks. ;) it was originally bought as sort of a joke, but I've actually become pretty fond of it.

[peejman]

Nice. Looks like it's working quite well and should do everything you need. I've considered adding some solar generation to my house, but last I checked the payback was much too long.  As prices continue to fall and efficiency improves, it might be worth another look in a few years. 

[div]

Nice. Looks like it's working quite well and should do everything you need. I've considered adding some solar generation to my house, but last I checked the payback was much too long.  As prices continue to fall and efficiency improves, it might be worth another look in a few years. 

 

I did a feasibility study for installing solar where I work earlier this year. The ROI was 27 years assuming no panel degradation over time - and the panels only have a lifespan of 25 years. Just didn't work. Now, if you can get in on one of the TVA programs where they pay you more than the going rate to put solar power back onto the grid that's a different story.

 

It really depends on what your goal is. For a small cabin that doesn't already have mains power or some type of vacation/bug-out setup I think it's completely feasible. You're not going to be able to run an air conditioner or traditional water heater off of solar, but it seems you can do pretty much anything else.

 

At this point my install is done. I'll probably post up how everything faired over the winter come spring. If anyone wants more info, or help figuring out a system for them let me know. I spent close to a year researching this setup and figuring out what I needed to accomplish my goals - I'll be happy to share what i've learned so far.

 

-div

[peejman]

I think the payback for a supplementary system for my house, including selling power back to the utility and the energy smart discounts and such was in the 17 year range. I have little confidence that I'll still be in this house in 17 years so definitely not worth it.

There's a house in my neighborhood with several panels on the roof. Either he knows something I don't or he can't do math. :)

[tnhawk]

Tennessee has spent 62.5 million for a 5 mega watt solar farm in West TN covering 25 acres with 21,000 solar panels.  They don't provide any information on ROI from the project.  I guess payback doesn't matter when the government is spending our tax money.

[Omega]

Tennessee has spent 62.5 million for a 5 mega watt solar farm in West TN covering 25 acres with 21,000 solar panels.  They don't provide any information on ROI from the project.  I guess payback doesn't matter when the government is spending our tax money.

Probably a large Federal grant for you know who's Green Initiative. So it wasn't out of our pockets it was out of our kid's kids pockets.

[Dirtshooter]

Thanks for all the info, I have bee contemplating one to put in my garage for some lights and to charge my cordless tools. I got to thinking about when we were out of power for 12 days during Katrina that I could do without a lot of electrical devices, but 2 things electrical I like is charging my tools and ice. We bought a counter ice maker at Sam's for right at $100 and I even tried and made ice in my pickup running off of the inverter. Btw it works like a champ, will make you ice in 6 minutes.  Ice just makes tea and water so much more palatable!! Solar is like a lot of other preps in that they may or may not be used much or be beneficial, but it is sort of like having a gun and not needing it.