12 volt solar panels

[JohnM]

When I originally set up my bus, I decided to us a 24v house system, and then used a dc to dc converter to 12v for the things that were 12v, range hood, toilet, water tank level indication, radio, TV etc. the 12v converter I got was a Jaycar 30a model, however, My reason for the 24v was that it was easier to connect them to the 24v motor batteries via a 3 position Marine battery rotary switch.
I was having problems with the house batteries going flat in a relatively short time, on investigation I found that the 24 to 12 v converter was drawing 0.8A on standby which added up to a lot of drain for little gain. I ended up putting the 24 12v converter behind the dash and using it for the Radio, GPS, Dash cam etc, and changed the house to a 12v system, changed all the lights to 12v LEDs, used a Redarc DC DC charger to charge the house batteries from the motor via an ignition relay, I have two battery chargers hooked up to the 240 v system, one 12v and the other 24v Because I had them, and the 24v batteries can be charged via the inverter, if required, I have 480w of solar for the house (4 x 120w panels) I also have two 50w panels in series that maintain the starter batteries. both connected via eBay special PWM regulators.
The starter batteries are two standard lead acid batteries where as the house are three 110ah Fullriver AGM. I would of liked to changed over to Lithium but unfortunately my old batteries died at the wrong time, and place so AGMs were my only choice.
I am not saying that my set up is the ideal, there are others out there that perform better (and some worse), but what I now have suits us and our needs, the batteries are normally fully charged by lunch under normal usage a little later if SWMBO does the washing. We have been virtually full time on the road for ten years usually only coming home for the Christmas break with the exception of this year, where we have been home for most of the year, The bus is parked in the back yard, with the fridge running as well as the car fridge (which is used as a beer fridge) and running a small freezer (which draws 840w per 24 hrs) off the inverter, the solar is maintaining the batteries to float, with the exception of last week when we had three days of heavy overcast skies and some rain when the batteries were down to 85% soc late in the afternoon. on a couple of those days.

[nut17]

Our system runs six 200w panels in parallel. 44.8v OCV and 36.7 Volts at maximum current. My Flexmax 80 Amp MPPT controller converts this to a very usable charge current from early in the morning when the voltage has reached around 20 v and a similar scenario in late afternoon. I recently measured with my clamp meter 78.3 Amps being delivered to my 600 Ah LiFePO4 battery at around 1.00pm in full sunlight conditions.(8 X 300Ah cells) If I was starting over, I would definitely use a similar system, but would probably opt for a pair of 45 Amp ETracer or similar controllers. My Flexmax Outback 80 is actually a Chinese "Fangpasun" knockoff sold to me by an unscrupulous eBay trader from Perth - No longer trading or answering emails. However it does seem to be functioning as it should and has been the heart of my on board power station for almost two years. "Touch wood"

Cheers
Chris

[T1 Terry]

If the Li battery was up around 13.6v when charging at the 78.3 amps that's around 88% efficiency so you couldn't complain about that, Chinese knock off or not. The Outback Flexmaster 80 is a great unit but up around the $1200 mark plus freight and the 80 amps derates above 40*C it makes them rather hard to justify that sort of price tag when for half that you can build a PWM system with 200 amp max capacity for around half that price yet still have as good or better efficiency by using matched voltage panels. I guess the Chinese knock off was a lot cheaper than the real thing so it still could be a worthwhile venture price wise if you were to find grid connect panels at a good price.

T1 Terry

[tarbaby]

Kappy
If you want to buy some 12v panels, have a look at Supercheap autos online. They were advertising 150w panels for $150. A couple of weekends ago they had them on special for $120 each, this may happen again during the post Xmas sales. Price includes freight to your nearest SCA outlet.
I have no idea what the quality is like, but they have a good returns policy.

[Craig]

super cheap online are not that price now. $489. holy crap.

low energy developments are selling on ebay cheaper than in their store. 150 watt = $149

[Kappy]

Well 14 x 100 watt solar panels arrived yesterday off Fleabay from vicroads for under $100 each delivered and took less than a week to get to WA.

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Well packaged and look OK , I put my multi-meter on 3 of them this morning in quite cloudy condition , we have some rain coming.

Got a consistent reading of 18 -18.8 volts and a round 5.7 amps.

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Some are cautious of ebay , but ebay and paypal have guarantees built in that I have used in the past when things don't work out.

[BruceS]

Do you have an item number Kappy? Or a link to them?
Not sure I can find Vicroards. (seller?)

[Kappy]

Sure Bruce mine also came with 2 metres of extension with Anderson plug.

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http://www.ebay.com.au/itm/391496125478 ... EBIDX%3AIT

[T1 Terry]

You have to laugh at the cable supplied with the Anderson plugs if it's anything like the 200w panels we bought for Brian's house boat. My guess would be 2.5mmsq conductor where a min of 4mmsq is needed. Double check the leads coming out of the panels for conductor size and connection, we replaced all of Brian's cables (well Brian did) with 6mm auto cable twin core so the conductor was 4.35mmsq. Some of the soldering the inside junction box let a tad to be desired, but for the price the bit of extra work is worth doing to get a good out come over the long term.
I guess they are QA rejects but with a bit of work they are great value for money.

T1 Terry

[Kappy]

As far as I can measure the cable supplied and coming out the panel is close to +2mm diameter (Thats the copper bit lol).

In any event the lengths they are serves no purpose to me really so as recommended I would replace anyway.

Re tested the panels this afternoon with less cloud and registered 21.75volts.