Hi Paul 

Actually many people have said to use house panels through a quality MPPT reg and it works well. I do that. Cheap to get second hand too.

BUT I do not recommend very large panels that are commonly used these days as basically they are a big pane of glass sitting horizontal on the roof of a van bouncing along the road, and with the possibility of stones and overhanging branches to cause trouble. 

 Just a note that you might be pushing that 20A controller a bit. If your panels are actually putting out the full power then in good conditions the total current produced at 12-14V will be greater than 20A. The current rating of a MPPT is the output current.  They do self protect but I think that is not a good design for long life !

Jaahn

I have the Victron 100/20, I was using the 75/10 but it stopped at 10amps for 120 watts. I suspected there was a bit I was missing out on. I can get up to 11.3amps output from the 100/20 under ideal situation with sun square on to 120 watts of panels (6 x 20 watts, 2 in series).

If you are in Victoria in winter the 100/20 will be ok, but further north in summer you will be missing out on amps. The 100/20 output is 20amps, that's it. Also I really wouldn't want to over stress the controller with it clipping the amp output. In the long run you may cook it. Personally I would want some headroom. Also the controllers throttle down if they get too hot.

Agree with others. Bumps in the road on large panels cause stress on the vehicle mountings. There is a lot of weight in that glass. Better off with twice as many small panels with more fastening.

Peter_n_Margaret wrote:

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4 full sized panels 350W each on a serious 4WD motorhome.
No problems. They are tougher than you think.
He used multiple small MPPT controllers (one per panel) for redundancy protection.

The vehicle is all electric (and diesel). No gas.

Cheers,

Peter

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 Hm 

Impressive but where is the air gap for keeping the panel cooler ??

I stand by what I said about big panels. Easy to use ones that are half that size and twice as many, there are other advantages also, but its the owners choice !! Like most things 

There is no point in asking for advice and then saying I did if different and it was OK ! People sometimes break smaller panels without doing much to them.

jaahn

I am sure you would have bolted them on in a structurally sound way so as not to rip the vehicle apart.

Too many people fasten things with string, wire & tape!

Yep, Sikaflex on fibreglass but both surfaces prepared properly. Not ever going to come off.

I had fairly large panels on the OKA and contrary to manufacturers specification, my panels were mounted along the ends. Given the millions of corrugations I inflicted on the system, eg Simpson Desert, Gunbarrel Highway, Canning Stock Route and Gibb River Rd on one trip, I was a bit concerned with "trampolining" of the panels so I cut lots of lengths of the giant pool noodle jut a little longer than the distance from the roof to the back of the panel and stood them on end under the panels so there was slight upward pressure on the panel and any movement was heavily damped.

Now the done thing for large motorhomes is to fit the largest panels that will fit - domestic 24 V nom up around 350 watts and nobody has reported any problems that I have seen

Like Peter, I'm not overly concerned about too-close spacing of panels and a little loss of efficiency because like Peter's OKA, mine had no fixed mains connection, and no generator so we obviously didn't care about wasting a few watt-hours

BTW overpanelling of quality regulators is a legitimate way of getting the power you need in summer, while increasing harvest in the off-seasons, buy adding extra cheap panels without going to the expense of buying large solar regulators