Vennwood Posted April 23, 2007 Share Posted April 23, 2007 Hi, I've read the various threads on solar panels and wondered if anyone had experience of the GPS controlled solar panels that claim to provide up to three times the output of static panels. It has always seemed to me that solar panels are best left until they are more mature. Certainly this has been the case with sailing. The first generation were pretty useless however the latest generation are pretty good however the problem has always been getting the best angle from the available sun. These GPS guided panels may be the answer however at the price of £1300 installed it is a helluva price if they don't deliver. Has anyone got any experience with these panels? Pete Link to comment Share on other sites More sharing options...
Dave Newell Posted April 23, 2007 Share Posted April 23, 2007 Hi Pete, I don't think they are GPS guided I think they just follow the sun and continuously adjust to give the highest output from the panel. D. Link to comment Share on other sites More sharing options...
Vennwood Posted April 23, 2007 Author Share Posted April 23, 2007 Hi Dave, The brochure reckons it uses the GPS data to work out position so it can track and follow the sun. The $64000 question is are they any good Link to comment Share on other sites More sharing options...
Mel E Posted April 23, 2007 Share Posted April 23, 2007 Pete, Dave is right - they don't use GPS. There are two suppliers, as far as I am aware - the French Alden companyand the German company that make the Oyster dishes. The Oyster version has a Sat TV dish on one side and 50 watt solar panel on the other - I guess on the basis that you'll be watching TV at night when the solar panels are 'resting'. But it's over £2,000. Talk to Bill who owns the UK Oyster franchise - he'll be at the Peterboro' Show - and he'll readily tell you why the Alden version is complete cr*p, not a sales approach that endears itself to me! The Alden uses a motorised satnav base but is only for a solar panel and can have various sizes fitted, though RoadPro, the UK distributors sell it as standard with a 100 watt panel. Basically it uses a program that checks its position at intervals and re-positions if necessary - this is to avoid it continuously 'hunting'. I believe it works on the basis of latitude, longitude and time of day (GMT) to position the panel rather than actually seeking the sun directly. This means that it points directly at the sun even when a cloud passes over. As to output, in southern Spain in the summer, it makes very little difference for an hour or 2 either side of noon compared with a roof mounted panel, but gives much more output in morning and late afternoon when the sun is at a lower angle - and, of course, in winter. But note that, at lower sun angles, the panel output will still be reduced compared with overhead because of atmospheric pollution. Is it worth it? Probably not unless, like me, you have an electric fridge. For most people, a roof-mounted 100 watt panel will more than do the job unless you have a succession of cloudy days or watch a tiresome amount of TV on a big screen! Based on measurements I've taken for ordinary roof-mounted panels, you should get, in total during the day, between 1.5 times and 3.5 times the output of a roof-mounted panel: the actual ratio will depend on your latitude and the time of year. But the downside is that you now have an active, motorised usit to go wrong instead of a passive one - and I have no knowledge of how reliable these sat dishes are (and remember, they stay fixed after they've found the satellites, so don't have to keep changing position). Of course, the panel still works if the motorised unit develops a problem. A cheaper alternative is that Alden make a roof-mounted device onto which a solar panel can be mounted, that allows you to tilt the panel to better face the sun - but it's manual. As to panels - they have been excellent for many years now and there are really no improvements to wait for. There is no new technology on the horizon and current technology is close to its limits in terms of watts per square metre. However, one point is worth stressing: most 'off the shelf' panels are manufactured to give an output of around 16.5 volts. This is much more than you need to charge a 12 volt battery - a 14 volt output is more than enough and gives you more amps for a given panel area thus putting more charge into your battery. For example, a 100 watt panel produces a tad over 6 amps at 16.5 volts, but over 7 amps at 14 volts. There are two ways of dealing with this: - Alden have introduced a range of panel especially for motorhomes that give a 14 volt output. - or, certain charge controllers incorporate a step-down transformer to change the 16.5 volts down to 14. Hope that helps. Mel E ==== Link to comment Share on other sites More sharing options...
Brian Kirby Posted April 23, 2007 Share Posted April 23, 2007 One further point that has occurred to me is that the actual gain from rotating and elevating the panel may not be so great as it may appear. For example, trees, mountains and buildings frequently intrude into the sun's arc, especially during the earlier and later periods of the day. Thus, whereas your expensive new control mechanism may be very good at aligning your panel exactly at the sun, this will bring no benefit when the sun is behind the toilet block!A lot of us do seek a bit of shade, for comfort, when siting our vans. However, the main benefits from motorising the panel can only flow when the sun is pretty much in full "view" of the panel. It therefore seems to me you'll need to pick the "sunny" pitches, if you're to get the best return from your additional investment. Link to comment Share on other sites More sharing options...
Vennwood Posted April 23, 2007 Author Share Posted April 23, 2007 Thanks Mel E, that's a great help. The one I was looking at is made by the German Oyster company. Transleisure at Newark have a special deal at £1300 and something fitted. It is slightly different from the Sat Dish version as it only has the solar panel at 85 watts. I guess I can buy a lot of batteries for that kind of money and I take on board Brian's comments about choosing the right pitch in relation to Trees, mountains etc. Decision made - I'll just add another battery for now and see how it goes if necessary I'll look at fitting a flat panel. Many thanks one and all Pete Link to comment Share on other sites More sharing options...
Clive Posted April 23, 2007 Share Posted April 23, 2007 Dont forget that you need to detract from the panels output the current needed to drive the control gear that points it in the right direction. If you really need that extra output you are better of just fitting larger / more solar panels on top of the roof. Less to go wrong. Use a switched mode regulator to ensure you take full advantage of the panels output voltage and don,t over-charge your battery. I normally waffle on at this point about those people who try and support Eberspatcher heaters with solar panels but on this occasion I will give it a miss. See you all at peterborough?? Regards Clive Link to comment Share on other sites More sharing options...
GJH Posted April 23, 2007 Share Posted April 23, 2007 Brian Kirby - 2007-04-23 1:02 PM A lot of us do seek a bit of shade, for comfort, when siting our vans. However, the main benefits from motorising the panel can only flow when the sun is pretty much in full "view" of the panel. It therefore seems to me you'll need to pick the "sunny" pitches, if you're to get the best return from your additional investment We decided we wanted a solar panel for use, mainly, when we go to civil war re-enactment events where we will have no hook-up. Having spoken to friends who have experience of panels at such events to evaluate our (fairly low-level) power requirements, we decided on a free-standing 50 watt panel. We used it properly for the first time at a rally at Easter and we were very satisfied with it. The lead is long enough for us to move it round manually from time to time to follow the sun, which is no hassle for us. I appreciate that we had a lovely sunny weekend at Easter and can't expect such good weather every time but, based on our friends' practical experience, we think the panel will be good enough for what we want and a heck of a lot cheaper than one fixed to the roof (moving or not). Graham Link to comment Share on other sites More sharing options...
Mel E Posted April 23, 2007 Share Posted April 23, 2007 Graham, Do make sure you padlock the panel in a totally unmoveable manner to the motorhome - a robust bike lock does the job. Free-standing panels have been known regularly to go for walks - and not come back! In general, I agree with your choice: if you re-position the panel about every couple of hours, you'll get most of what a motorised dish will give without the expense, extra height on your vehicle or more to go wrong. However, you do need a proper stowage place for the panel (it is surfaced in glass, after all) and you also should fit it with a socket (so you can't short out the leads). Fit another socket to the motorhome floor and use a lead with a plug on each end to connect the two. I really don't like crocodile clips for this, 'cos sooner or later something nasty will get shorted out! Mel E ==== Link to comment Share on other sites More sharing options...
GJH Posted April 23, 2007 Share Posted April 23, 2007 Thanks Mel, all good points. Mel E - 2007-04-23 5:41 PM Do make sure you padlock the panel in a totally unmoveable manner to the motorhome - a robust bike lock does the job. Absolutely. The panel actually comes with a "built-in" bike-lock cable but I found the other week that the padlock wasn't all that good - I now have another padlock :-D We also have a couple of combination cable locks for our bikes so have "extensions" if needed. Having said that, our normal usage will be on private, guarded, sites to which the general public are not admitted. Mel E - 2007-04-23 5:41 PM However, you do need a proper stowage place for the panel (it is surfaced in glass, after all) The panel came in a padded bag and we also obtained some light foam pads which we place on the glass side. I spent some time working out safe positioning for when we are travelling and I'm sure that won't be wasted time. Mel E - 2007-04-23 5:41 PM you also should fit it with a socket (so you can't short out the leads). Fit another socket to the motorhome floor and use a lead with a plug on each end to connect the two. I really don't like crocodile clips for this, 'cos sooner or later something nasty will get shorted out! One of the attractions of this particular panel is that its lead terminates in a plug and it is supplied with another lead which has a socket at one end and ring terminals for permanent attachment to the battery terminals at the other. The lead is neatly coiled in the battery locker when not in use and the plug/socket can be connected/disconnected with the locker door shut - hopefully should avoid any shocking experiences :-D Graham Link to comment Share on other sites More sharing options...
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