My Large Solar Setup

[charles_m]

I thought I'd do a thread about my solar setup. I haven't seen any on here as big as mine, and I think some of the products/methods I used might make some people have a better understanding or get some ideas of their own about solar power.

Quick Stats:
2 fully independent systems:

12V system with 1 300 watt panel into a PWM controller into an 8D battery in the original battery location. I use this system for the 12v lights, the starting and running of the bus, the water pump, composting toilet vent fan and ceiling vent fan.

24V system with 3 300 watt panels into a Midnite Classic 150 charge controller into a 24V battery bank consisting of 8 6v lead acid batteries with 12kwh of capacity into a tripplite inverter with 2400watts of continuous output. I run my fridge, 20 gallon hot water heater, house lights, computer, electric tea kettle, air conditioner and whatever else 120v stuff I want. I seem to generate about 4kwh a day easily.


The bus has 4 300watt Trina panels mounted on the roof using a racking system made by Unirac


The panels are combined in a rooftop combiner box made by Soladeck, right now, Im just stringing all 3 panels in series for the 24v system and the 12v panel just has a home run MC4 straight to its charge controller. I only use the buss bars and combiners for the 24v system.





All my DC wiring for the 24V system goes through this box where my inverter and charge controller connect to the batteries. I have a shunt for measuring my ah in an out of my house batteries. Every run of wire has a breaker on it and the charge controller has arc and ground fault protection built in.





Scored a nice little AC breaker box. Hard to find these new anymore



All buttoned up



Right to left: 12V system charge controller, 24v system charge controller, 120v breaker panel, 24v breaker panel, inverter

The cables from the 24v battery bank are 0000gauge with 00 gauge battery interconnects--all the same length. The wire from the inverter to the DC box is 00 gauge as well. BIG WIRES=Good life

[nat_ster]

Great info.

I look forward to updates.

Nat

[m00py]

charles_m: None of your images are working. I would love to see what your setups look like!

[EastCoastCB]

Originally Posted by m00py

charles_m: None of your images are working. I would love to see what your setups look like!

no they are not.

[Tango]

Same here.

[charles_m]

Sorry guys! Stupid image hosting. bleck!

[charles_m]

I've noticed that the 300watt panel is overkill for the 12v system. I knew that would be the case so I think I'll be eventually changing my setup to be where all 4 panels feed into the 24V system and then use a step-down 24v-12v transformer or some such device to maintain the 12v side. This will be my first winter in the bus and I want to make sure I am making the best of my setup. Does anyone have experience in this? I was thinking of using a cheap PWM charge controller and just hook the 24v batteries up to the solar input side of the CC and the 12v batteries up to the batt side. I cant think of why this wouldn't work.

[charles_m]

24V 7.5A DC Input Battery Chargers for 12 volt Lead Acid and SLA Batteries from PowerStream

I like this, but it seems too expensive for only 7.5amps of charging

[family wagon]

Powerstream is not so far from me and I've done business with them a few times. They're good people. That said, I can understand the reluctance over a $185 charger.

Above you listed "12v lights, the water pump, composting toilet vent fan and ceiling vent fan" as the 12v loads. (also charging the starting battery, but things could be simplified somewhat if we ignore that battery and let it charge some other way) With no house loads running on it, the starting battery could probably sit for weeks or months and occasionally be topped off with a conventional battery charger run off your inverter.

You could look at a basic dc-dc converter to run those loads directly and shave some money off. The PST-DC/2812-8 ($160), or several options ranging $39-$130 here and there might be interesting.

Call Powerstream and ask for tech support to help select a product for your application. They've been pretty helpful when I have spoken with them in the past. They're in the Mountain time zone.

[slaughridge85]

I'm looking to use the same charge controller from midnight. Any issues with it or is it as good as it sounds? Done lots of reading but never heard any reviews from actual owners...

[nat_ster]

We use midnight charge controllers on the massive solar array that runs our 12 bay bus shop.

Never had a issue with them.

Nat

[charles_m]

I like it a lot. They have great tech support. I originally didn't care to much about the extra features of the Midnite, but now that I have them, it's worth it. It also saved me from feeling like a battery monitor was necessary which saved me about $180. I haven't been able to get batteries below 80% yet and I run the hot water heater (2000 watt element) for 45 mins a day which is all it takes to get 20 gallons up to temp and it holds all day. I end almost every day with 99%-100% full batteries and wake up with them at 94-96%. I wake up, run the hot water heater for 45 mins, take a shower, and then shut it off. By now the batteries are at about 87% or so between the overnight usage by the fridge and the hot water heating of the morning. The batteries are charged again by sometime in the early afternoon, depending on the sun. We haven't had a long streak of cloudy days since I got my system running, and we'll see how winter goes, but I still have another 300 watt panel I will be bringing to the system once I figure out a better way to keep the 12v system charged. I was skeptical about using an electric water heater, but so far it is working out really really well to my surprise. I was planning on using a separate solar hot water system as the primary hot water heat source, but now, it doesn't look like that will be needed. If is still needed more hot water or electricity, I could easily add another 2 300 watt panels to my rack and combiner box for a total of 1800 watts of solar panels. The cool thing is that, at this point, I can increase my power generation by 50% and it would only cost me $450 (10% of the pv investment so far). The controller, batteries, etc. al are already more than capable to handle it. I estimate I would be making around 7kwh on a good day, with 12kwh in storage. I mean, in 1 day, I could use 15kwh, and still have 33% of my battery remaining for the night...wake up and have 25%, then have it charged back to full in 2 or so days... Some would say that that only makes sense if I have a bigger battery bank. But the way I see it, I'll be making great energy even on cloudy days which means that, save a nuclear winter, the number of viable days I have for charging my batteries will be HUGE. It could be a cloudy day in december and I'll still cop a great charge. I want to be able to weld, use my power tools, compressor, etc... we will have to see once I get a new project going. I love electricity and would love to ditch the propane stove someday--it's the only fossil-fueled/manufactured energy source I can't work around in a way i like..yet..

[family wagon]

That's great to hear your electric water heating is working out so well. Is that a 24v element direct from the batteries, or 120v via an inverter..?

I recently picked up a "NuWave PIC Pro Titanium" portable induction hot plate hoping to use it instead of propane for cooking in my bus. Turns out I have only cast iron skillets and a 10 quart pressure cooker that work with it.. gonna have to get induction-compatible sauce pans to really try it out. My old-school revereware isn't magnetic.

[nat_ster]

Glad the solar is working out for you.

I will be keeping a eye on this thread.

Nat

[fostertown]

Charles,
Would love to see what your battery setup is like. I think my system setup is going to be very similar to yours, I just picked up a midnight solar classic and 3 300w panels from a mutual friend (would've gone with 4 but my bus is a bit shorter and lacks the space)

[charles_m]

I have 8 Trojan T105s mounted under my bus in a underbed tool box I bought from Tractor Supply. Lets meet up sometime. Im hardly ever on here 303 9311904

[onenationundergoat]

Hey charles, we've found a great deal on 245w solar panels used for $50 each and were thinking of getting six of them. According the place that's selling them, this charge controller is adequate: 30A AMP PV Solar Charge Controller PWM w/USB 12 Volt Solar Panel Battery RV Boat - ML Solar
30A AMP PV SOLAR CHARGE CONTROLLER PWM W/USB 12 VOLT

Would I be able to string all six panels together in series, or should I break them up to 3 and 3? And if so would that require another charge controller? We currently have one large 12v deep cycle battery and are planning to add 2 more to our system. Electronics mathematics makes my head spin. Our electricity setup is basically just two extension cords with 3 power strips wired into each, so we can plug them into either the inverter or the generator. So I'd imagine that we'd just do our solar as 12v and use the inverter? What is 24v for? Final question; how would you recommend bracketing them on?

[Iceni John]

I just posted a brief description of my 8-panel set-up in the "How did you attach your solar panels?" thread - it may give you some ideas. It's well worth spending time reading the Northern Arizona Wind & Sun forum for good solid advice on what to do and what not to do - those folk know way more about renewable energy and PV than I ever will, so I take their recommendations seriously.

John