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Forum Index : Solar : Caravan Solar System
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Yeah, I have seen these arguments before (MPPT vs PWM) they are a bit outdated and mostly miss the point. The modern MPPT regulator gives you more flexibility and choice in selecting panels and the price of panels has dropped a lot. If you have very limited area to mount panels.... yes you may need to scrape those last few watts up. In your instance if you go with the 2 x 70 Ah batteries. your wont want to drain more than 60 Ah total from them overnight. Your limit to charge them will 20% of total capacity (guessing here) so that is 28 amps per hour max in bulk charge. so even at 20 amps per hour minus the fridge , average sunny day, you will hit absorption stage by lunch time and the current that the battery will take will dwindle to 1.4 amps over the next 90 minutes. OK, so you may not do it in June and July in the south, run the generator for an hour in the morning and the panels will finish the job during the day. If you are using more than 700 watts overnight in a caravan somethings not working (water-pump priming, inverter not sleeping). You system will run at MAXIMUM EFFICIENCY for 2 hours a day or less. Whats that? 80 watts extra or 15 minutes less charge time  Is it really worth it?
Yes I do need a holiday but I'm outdoors 7 days a week, so perhaps a secluded resort may be more my thing, I have heard those recliners are dangerous and possibly fattening  I'm confused, no wait... maybe I'm not... |
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Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All The batteries I have are new 70ah, but they are on a small electric forklift, and the thought was that if I can't sell it, then scrap it and use the batteries. On the other hand if 2x 100ah batteries is a better option, then I may have to change my thinking. (again) Then with 2 x 24 v 200 Watt Panels = 11.22 A x 5 = 56.1 A x 242v = 1346 Watts. Sounds like I better redo my wattage list. P.S. It is not the recliners that make you fat, it is the stubby holder in them. 
Regards Regards Hervey Bay Qld. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
sorry, I have reread my own post and I cant see where i said you need bigger batteries, perhaps it is just poorly written. you need to decide when you will turf the old batteries out and replace them and design your system around that. My personal rule for a battery rated at 3500 cycles (10 years)If I drain more than 50% I subtract a week and if I cant get it 100% full the next day subtract a week from its lifetime.There is no shame in replacing a battery after 18 months if it has done the job you want. Oversized/undercharged batteries get sulphated and that is a real pain to deal with. Download the battery specs and graphs you will need this to get thing right. your 420-470 watts a day may be a little on the low side but it shouldn't be far off. Probably 300-350 watts overnight, that's a pretty good margin. The amount of power you generate per day can fluctuate wildly due to the natural enemy's of the solar panel,....the tree and the cloud  but there is an upper limit every day depending on the latitude and time of the year. If you look at the figure in my solar clipping posts I reckon I can do a max of 389Wh/day with a 190 Watt panel in June (sunniest day in the worst month)at my place.
cheers yahoo I'm confused, no wait... maybe I'm not... |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All Yahoo2 you are correct, the new list below. Larger batteries means more storage = more available to use. If I am living in this van for 1.5 to 2 years, I don't want to have to turn things off before I can use something else. Yes , we have to be frugal, but not paranoid. I have purposely added all items as if they are all used on the same day. IE: TV and Laptops are variable. The Microwave may be used on the Generator, and then not every day. The only item I am still researching is a bedroom fan. If it is really bad, then the generator will run the Aircon, but otherwise a few hundred watt of fan for a couple of hours may be a good solution for nights. Fridge-----= 60 Watt = 720 Watt / Day = 12 Hrs Lights-----= 8.4 Watt = 42 Watt / Day = 5 Hrs TV---------= 25 Watt = 125 Watt / Day = 5 Hrs Water Pump-= 24 Watt = 24 Watt / Day = 1 Hr MicroWave--= 1526 Watt= 457 Watt / Day = 20 Min Laptop-----= 75 Watt = 375 Watt / Day = 5 Hrs ----------------------------------------------- ----------------Total-=1743 Watt / Day ---------Or-----Total-=1286 Watt / Day PV = 2 x 200 Watt-----= 2000 Watt / 5 Hr Day Overnight usage (after Sunset) would be between 500 to 600 Watt. Using 30% drawdown from 140Ah = 140 x 12 = 1680 x 0.3 = 504 Watt I guess creating some usage history is the only way to decide if the battery capacity should be larger.On the other hand, the extra cost for larger batteries may outweigh replacing 2 x 70 Ah earlier Regards Hervey Bay Qld. |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All For those interested, Caframo Sirocco Fan The caravan community swears by them. 0.4 Amp at Hi Speed. Regards Regards Hervey Bay Qld. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
yahoo's tweaks for the Dinomobile 
daily totals Fridge------= 43 Watt = 10 Hrs= 430 Watt/ Day Lights------= 15 Watt = 3 Hrs = 45 Watt / Day TV---------= 25 Watt = 5 Hrs = 125 Watt / Day Water Pump= 24 Watt = 2 Hrs = 50 Watt / Day Laptop-----= 75 Watt = 5 Hrs = 375 Watt / Day inverter----= 08 watt = 3 hrs = 24 watt / day rechargables 0 watts charge in the afternoon ----------------------------------------------- everything --190 watts 15 amps maximum current draw Total-=1050 Watt / Day 86 Ah MicroWave--= 1526 Watt= 457 Watt / Day = 20 Min I am ignoring the microwave! Average hours Overnight usage (5.30 pm till 8.30 am..... 15 hours) Fridge------= 43 Watt = 6 Hrs = 270 Watt/ Day Lights------= 15 Watt = 3 Hrs = 45 Watt / Day TV---------= 25 Watt = 3 Hrs = 75 Watt / Day Water Pump= 24 Watt = 1 Hrs = 25 Watt / Day Laptop-----= 75 Watt = 2 Hrs = 150 Watt/ Day inverter----= 08 watt = 3 hrs = 24 watt / day total load 590 watt/ overnight = 48 Ah total load 460 watt/solar hours = 38 Ah solar generated in south Oz PV = 2 x 190 Watt June ------780 watt/day Septober---1870 watt/day Dec-Jan--- 2960 watt/day Mar-Apr----1680 watt/day subtract ?? % for system losses (pick a number between 5% "ya dreamin" and 50% "shortcuts R us") Remember to factor in at least 1 hour of low charge to top up the batteries, the excess can still be used for other stuff. Calculating battery level from the spec sheets. Using C20 available Amp-hours for zapinator? brand battery 70Ah x 2 = ????? 48Ah/???? = ? % battery capacity used my opinion looking at these numbers and my personal experience, 400 watts of panel is going to be borderline, unless you can shave an extra 150watts/day from your total,I reckon that wouldn't be to hard to do.. Even then it will be a miracle if you get a campsite that is not shaded for part of the day.  If I was doing it (which I'm not) I would install a multi voltage 60Amp MPPT then get as close to 800 watts of panel as I can with the roof space available. If a full set of big panels wont fit, I would wire some smaller ones to match (its not easy but it can be done). hope this makes sense, it looks a bit long winded. I'm sure someone else has more idea about vans than me. regards Yahoo I'm confused, no wait... maybe I'm not... |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All Yahoo , many thanks for that detailed analyses. By, the way, a Dinosaur needs a much bigger van.
I have room for 4 x 200 Watt panels, or I saw an add for 250 Watt panels. So, 600 Watt is the next best. Additionally, the Laptop will be a usage that probably will reduce after the first few weeks.When the novalty of bragging wears off. Hoping to limit the use of the Generator to once a week when the washing machine is run. I agree with the 60 Amp MPPT. We are leaving the purchase of the solar system till about Febr /May when we will only have a few months left before we sell the house. However, the brief is, we must be self sufficient, so if more panels / batteries are needed, so be it. So, after all the very helpfull posts, I think : 3 x 200 Watt PV's 2 x 100 AH Batteries. 1 x 60 Amp MPPT regulator. 1 x 2KVA Generator. (would have liked Diesel , but they are noisier) Regards Regards Hervey Bay Qld. |
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norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Now you are "on the money" Dinosaur, Missus and I travelled OZ(detecting for gold with some sightseeing) for 2years 99 and 2000, in self contained Troppie, 40,60,and 2X80watt panels flat on top of sleeping facilities whilst travelling, angled to the North at approx 20` whilst camping(sleeping underneath). Danfoss BD35 in fridge/freezer, Honda battery charger(2 stroke)(hardly used). Notebook with GPS and moving map software(Ozexplorer)complete 250k of OZ topo maps in digital form and georeferenced. All cooking done on campfire, clothes washing on a every 2 weekly overnight stop at a caravan park. Very few drama`s, one in Vic State forest. Drained battery(too busy detecting to monitor properly) time to resupply and batteries too low to start troppie, no fuel for genni but missus had a litre of metho, added a bit of oil and after much pulling got gennie to run long enough to get vehicle battery up to start. If you ever run a gennie on metho get prepared for the intoxicating and distintive odour. Most enjoyable trip would be still on trip if Missus had not missed all the creature comforts of home. Trust you`ll have room for my detector too!!!! We come from the land downunder. Vic |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All norcold, I have browsed the oziexplorer site and concluded that having a laptop with gps is a fantastic way to record where you have been / going. Not that you would have the laptop On whilst driving. We would use our normal gps for that. My question to you is, what did you use besides the oziexplorer package.? I can get a usb gps device , or buy a gps like Magellan. Do they connect to the laptop and allow download of gps data stored ? I like your inventiveness with the Metho. Reminds me of the time the landrover back axle slid out of the vehicle by about 300mm. Lost all the brake parts in the dust when I went for the brakes. Missus went looking for them while I had to panel beat the axle tube round again. Then finally had to pee in the brake system to get that to work. Spent 8 hours in the middle of nowhere, but got going again. That was 45 years ago, hopefully this trip will be smooth sailing. Regards Regards Hervey Bay Qld. |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Used a Magellan handheld(gone through a few) with a serial interface, laptops than didn`t have USB(early 90`s). Newer Magellans have USB. The handheld GPS makes the combo much more versatile(over just USB GPS) as have used one extensively in my pursuit of gold, could save waypoints of gold finds, than download to laptop map. Originally used Fugawi software than purchased Ozexplorer when it came out. It is much more user-friendly. When I first started out there was no digital maps, so scanned paper maps on a A4 scanner stitched them together digitally with Panavue than imported and georeferenced with moving map software. Lot of time spent but it paid off on our travels. Although now we have vehicle navigators, I believe the handheldGPS-laptop combo is a very worthwhile tool to carry on our travels not only for its ability to save waypoints but a handheld GPS (used properly)adds safety when in our outback. You do not have to move far from a vehicle in WA to be lost. They are very cheap now, think my first was a little over 2grand. Myself I go for the most basic one with PC interface(USB now), for simplicity of use and longer battery life plus like all tech the next model is better and cheaper. Found the Magellans did the job always but spend some time practising taking walks and using GPS to return you to starting waypoint. We run across a lot of travellers who believed they were not accurate, I believe in all such instances it was operator error. Cannot comment on other GPS as only ever owned Magellans. Oziexplorer is also available for WinCE and Android devices, using same maps and data as PC(maps modified by PC)have currently got it installed on a Chinese 10inch Epad. Great but not as versatile as handheldGPS-laptop combo. Some of the Chinese navigators use WinCE OS thus can use oziexplorer as well as navigator software they come installed with. Dinosaur I`m helping you spend a lot of money here, if I keep going and get onto fishing you`ll need a semi and a dog or two. 
We come from the land downunder. Vic |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All norcold, you wont make me spend any money that I don't want to spend. At the moment I am looking at some way of recording where I have been, and it is possible that an Android app will do that job, as my phone has gps. FISHING Hate it with a passion, don't eat fish, and can find better ways of
wasting time. IE: Watch Grass grow. Thanks to all you guys for helping me with the solar. Just for your reference: 3 x 200 Watt PV 24 vdc-= $1080 2 x 120 ah Batteries---= $600 1 x MPPT Controller 60A= $480 Total------------------= $2160 OR 5 x 120 Watt PV 12 vdc-= $1345 2 x 120 ah Batteries---= $600 1 x PWM Controller 50A-= $100 Total------------------= $2045 Bugger all in it, so MPPT it is. Regards Regards Hervey Bay Qld. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
If you are looking for ways to spend the hard earned $ 
$15 each, very good value only downside, it is possible to bump the buttons and be looking at the daily minimum or the room temp and not know unless you have a close look at the screen yahoo I'm confused, no wait... maybe I'm not... |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All No Link ? Regards Hervey Bay Qld. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Sorry Dinosaur I only buy them when they are on special, I don't have an invoice for the last lot so I am not sure where they come from. I have neglected to mention the other option for keeping a deep cycle bank topped up, for those of us that are not caravaners. A DC to DC battery charger, a company in South Australia have just won an award for one of their range. 
I am guessing it would be this one, which has a MPPT panel regulator incorporated in the design. The idea of these is they take power from the alternator and boost or buck the voltage to the correct level to charge deep cycle batteries. Its a perfect solution for vehicles that have minimal or no space for panels and spend a large percentage of their life with the motor running but need to draw significant amounts of power when the vehicle is not running. for example trucks 4x4's. I have a couple of machines with DC motor driven hydraulic pumps so I should be using this setup myself  I must just love buying batteries!
They also play nice with modern electronic systems. REDARC gear is not cheap, it's robust functional and plain so its probably not the first choice for weekend warriors and posers, but its a good concept. Properly installed in a modern long haul truck it would pay for itself and the deep-cycle bank in about 20 months. yahoo I'm confused, no wait... maybe I'm not... |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All Yahoo , thanks for the info. When it came to Solar Panels, I came here cause the caravanners forum became a sh*tfight. And I can see there are some dedicated solar experimenters on here. I did ask the question on the caravanners forum about the chargers, and it makes interesting reading. My Question This is one of the chargers I am considering.TriStar This is another, which has a nice software package to go with it. Mppt SCC-2 It appears the Mppt controllers come in their own when you are controlling 40Amp or more. The extra charge to be got from them is mostly in the morning when the panels are cold. And that is when you need it most. But also seems the best option for AGM batteries. Got my 260 ah battery in the other day, 67 kg. Was quite a hassle getting it in under the seat in the caravan. Now I have to setup a bussbar system with fuses etc in prep for the MPPT controller. Regards Regards Hervey Bay Qld. |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Dino, I do use a MPPT controller to charge the battery bank that powers my house. My observations are a bit different from what you say above. MPPT utilizes the portion of power that's contained in the panel output voltage above the battery charging voltage. For example, with my 24V battery bank about 27V is required from the panels to push a charging current into the battery bank. Now, while the panel open circuit voltage is around 44V it sits at around 34V when the MPPT demands the max charge it can get from the panels. So, I'm getting the power of 34V at the panel current instead of 27V at the same panel current. You can work out for yourself which is higher. To check this all out I have rigged amp meters at the MPPT solar input and at its output to the battery bank. In my set up the output is consistently higher by 2-3A from what's coming off the solar panels. For MPPT to work you need a panel voltage that's a fair bit higher than the battery charging voltage. Some 12V panels (30 cell types) would not give any benefit by using a buck MPPT controller. Some MPPT's are buck & boost, meaning they can still charge a battery even when the panel voltage is below the battery charging voltage. I have two 15A MPPT's that do just that, charge the battery even in low light but provide then only a small current (better than nothing), of course. Unfortunately these controllers are now too small for my ever getting larger battery bank. With regard to the charging regime of your battery type (flooded,AGM, etc.) you select a MPPT with a suitable output, not all do have that select ability. But, the MPPT principle has nothing to do with battery chemistry. Klaus |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
will be fascinated to hear what panels you use and how they will be wired to meet the 40 volt minimum criteria.edit (for the scc-2) Morningstar Corp morningstar string calculator this is a mockup for a 48 Volt system, yellow is over volt, blue is under volt and red is over current. 
I'm confused, no wait... maybe I'm not... |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All MPPT utilizes the portion of power that's contained in the panel output voltage above the battery charging voltage. Tinker , I would have thought that a standard PWM unit also does this, but by narrowing the pulses and thus the voltage.
Some 12V panels (30 cell types) would not give any benefit by using a buck MPPT controller.
I was going to use 24 v pv's, which I assume yours are as well.
you select a MPPT with a suitable output, not all do have that select ability.
Understood that , but found that more of the later MPPT controllers seem to address that issue.
But, the MPPT principle has nothing to do with battery chemistry. Tinker what controllers do you use ? will be fascinated to hear what panels you use and how they will be wired to meet the 40 volt minimum criteria.edit (for the scc-2) Yahoo ,I had to re-read that brochure before I finally found that statement, but I wonder if the 40v is for the 48 version. Will email them and ask the question.
I have not used the calculator before, but wonder if the aim is to achieve a Green line. Have to read and try it. EDIT: Also pretty hard to find out the panel manufacturer on cheap evil bay uunits. Looking at OzPlaza 200 Watt 24 v units. Regards Regards Hervey Bay Qld. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
MPPT60-1 unit from GSL Electronics. I got mine from Altronics, they also sell smaller versions. Klaus |
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| Dinosaur Guru Joined: 12/08/2011 Location: AustraliaPosts: 311 |
Hi All Tinker, I have read bad reports about GSL. In particular taking months to repair faulty units. Also looking at the the boards, they look like hand soldered units employing through hole technology. What is your opinion. Regards Regards Hervey Bay Qld. |
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