#8108  by Helen&Steve
 Fri Aug 21, 2009 3:43 pm
This topic is very interesting at the moment as I am thinking of upgrading our 80w BP solar panel system to something more grunty. The options at present would be the 120w panels, maybe two if Santa was kind, coupled to the new morningstar controllers which are due to be released in Sept.

They incorporate the mppt technology with approx 10-30% greater efficiency. Would imagine that some of that is hype but the new products are expected to be good on price for this technology and offer greater amps handling. Their lower end unit is 15amps when I last looked.

I have been reading Collyn Rivers book on solar power for motorhomes and can recommend it for getting your head around some of the terms used.

Steve.
 #8115  by Ross
 Sat Aug 22, 2009 6:23 am
We recently added some Suntech 85W panels to our existing ones - I'll tell you in 20 years time how they lasted :)
We got them from AA Solar, as in http://www.aasolar.co.nz. He gets them in by the container load, and prices vary as the dollar fluctuates etc. I see they are monocrystalline. He currently lists "on special" the 85W panels at $699 and the 140W panels at $1099 - which is keen pricing :D The panels work well and I am very pleased with the output.
 #8117  by Ross
 Sat Aug 22, 2009 7:04 am
The Flying Tortoise wrote:.... and in the case of solar panels in particular... get the biggest that will fit the available space or that your budget will s t r e t c h to! Don't scrimp with Solar!
Couldn't agree more. The cost of installation and controllers and wiring and meters is considerable, so the more square cms of panel you can add the better - adding more later can be a lot more expensive. Of course it depends on how you'll be using your motorhome. If you're mostly going to stay in camping grounds on power and freedom camp only in summer and have very frugal appliances then it's probably not a problem. But if you want to live off the grid in winter and watch TV on the (big) screen and use the laptop then powering it all is a problem. A system that runs well in summer can be a constant worry in winter when solar generation can be half or even a third of summer output. Winter is a vicious circle. Supply is less because of more clouds, lower angle of the sun, and less daylight hours - a triple whammy. Plus on the consumption side less daylight means more hours of lighting, more heating (the diesel heater sucks a bit of power esp on startup) and more watching TV and cruising the net. So for the poor old batteries it is the perfect storm :shock:
Sometimes the power inbalance can be overcome by using a generator, but there are plenty of places a generator is not allowed or is not appropriate.
So I agree; with solar get the bigger one if you're not sure. And in any case, set it/them up to allow for more to be added in future, in terms of wiring and spacing on the roof and controllers.
 #8118  by Ross
 Sat Aug 22, 2009 7:34 am
johnaye wrote:... ex maui merc. I run a 12/240 fridge...
Hi John. How much does the fridge require to run on 12V, like what does it draw? I guess it must be fairly efficient if you're able to manage at present. I'm horrified at how much our 175l Dometic sucks when on 12V - like about 11 or 12 amps/hr. That must be only when it's running/working and I suppose there must be long periods when it doesn't need much at all so long as the door remains shut. I think I saw where a 100l fridge required about 40 amphours over 24 hours. Our fridge is 3 way, which is lucky because otherwise I'm not sure where we'd find the power to run it over winter. I remember a bus conversion company advising that to run a fridge just off 12V would require 2 large solar panels just for that. That'd be a fridge in the 175l range I guess, and having been through a winter I'd think running a large fridge just off 12V all year round would need more like 3 or 4 solar panels. So... do you know how many amps your fridge is going to need over 24 hours of use? Also will you increase your storage?
A few years we bought an ex-Pacific Horizon rental rather than a Maui mainly because it was better set up for freedom camping - 3-way fridge and gas heating. Maui are still naughty, sending out tourists only able to heat their motorhomes by running the engines or plugging in to 240V. I don't know if they've improved the fridges or not.
 #8120  by Roamnz
 Sat Aug 22, 2009 7:44 am
Hi Ross I thought you were up in the glorious winterless North! Wait til you get back down south, then you will remember how low the sun can be in winter.

How much Solar do you have on your Traillite now and what size Morningstar solar controller are you using with the increased capacity?

I have been having a browse on your blog, ( and had a laugh )) sounds like your A frame looks more like a C frame now, is it still operational? Shame you are not able to attend the Traillite TGT in Christchurch in October, there is a workshop there and I could have repaired your A frame for you :) cheers Grant
 #8121  by Ross
 Sat Aug 22, 2009 7:55 am
Helen&Steve wrote:...coupled to the new morningstar controllers which are due to be released in Sept. They incorporate the mppt technology with approx 10-30% greater efficiency. Would imagine that some of that is hype but the new products are expected to be good on price for this technology and offer greater amps handling.
The mppt stuff sounded like magic, or alchemy .... getting more power out of existing solar panels. Like running your car on water ... The 30% efficiency gain is probably downhill with a tail wind at the south pole on mid-summers day. However, the guy from AA Solar reckoned he'd tested them over a year and thought 8-22% improvement more likely. And apparently the best improvement is in cold sunny places.
Anyway, I was convinced, and have been running an mppt controller since July and have been impressed. Ours is a Votronic, which fitted neatly into the space of the Morningstar 30. We boosted the solar generation at the same time, and I don't have any accurate comparisons. However, the boost in generation was beyond my expectations.
I'm not sure the cost would be worth it if you only had 1 or 2 panels and had room to add another. But heck if you have 500W of solar panels and no room for more, a 15% increase in efficiency by way of a controller is a no-brainer.
 #8124  by Ross
 Sat Aug 22, 2009 8:33 am
Roamnz wrote:How much Solar do you have on your Traillite now and what size Morningstar solar controller are you using with the increased capacity?
Hi Grant. we added 3 X 85W to the 2X 130W so that's ... umm.. carry the 1..... that's 515W. And we had a 30W Morningstar which would have coped, but now have a Votronic MPPT which I think is 45W.

[We're working on Plan B which means we might make the Traillite gathering in Christchurch. I must did out the printer and get the form filled in and away. Thanks re the A-frame but it's beaut now, no longer a V-frame or as you say C-frame :shock: ]
Regards, Ross
 #8126  by Roamnz
 Sat Aug 22, 2009 8:47 am
thanks for that Ross, with all that extra weight on your roof, have you changed your 7 tonne sticker to an 8 Tonne sticker :roll: :)
Were you able to find enough flat space on your roof to put the new panels on or have you put the new panels on the sloping part of the roof?
Like the sound of that much solar, with that much power you will be able to hook up to the national grid in summer and sell power back to Contact Energy!! cheers Grant
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