Solar panel advice
Looking for advice please.
We are looking at getting a solar panel so we can go "off grid" on occasions.
We are looking at a 100w 10amp panel at around £100.
Is this large enough to charge the leisure battery and run the 12v system within our 2010 Odyssey?
We do not - as yet - use the caravan during the winter months so only looking at using the panel between the months of March to October.
If we did want to use our 240v TV and the microwave what would we need to do/buy as well.
Thanks
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What you suggest would be ample to run your 12v system for a few days, weather dependant. To run the 240v system you would need an inverter and I have no experience of them. I charge all my camera, phones, I pads etc using the 12v system. Never take a telly with us and Mrs One doesn’t use a hairdryer etc
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Are you intending to have the panel on the roof or freestanding? Freestanding are more effective. But I think yes 100w would work between March and October. This also depends on TV wattage. It is a 65” plasma and you want it on 20 hrs a day then the answer is probably no. The other watch out if you are going off grid for the first time is your leisure battery in good condition. Maybe spend a day on a ehu site with the orange lead disconnected. To make sure all is well. If you want to run a 240v tv then you also need a inverter to convert 12v to 240v but a 12v tv is probably a better bet.
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I have 100w panel fitted to my van. This give a theoretical 8.3A realistically 4 to 6A depending on available sunlight. I run heating as needed, water pump and 12v TV for a couple of hours a day no problems over 3 seasons. This time of year I would use a mains hookup.
To run 240v equipment you will need a 12vdc to 240vac inverter. These are not 100% efficient and can draw large currents at 12v. Personally when off-grid I use a 12v TV. The Aldi ones at around £110 are perfectly useable.
Imo it is not really feasible to use a microwave due to the required power. However some do, albeit with banks of batteries and KW rated inverters. Quite costly and heavy for a caravan load margin.
If you do want to run a 240v TV a 100-150w inverter may do the trick, in the past I have used one (about£35), The TV was about 50w at mains voltage and via inverter drew about 5A from battery at 12v. My recent 12v TV draws about 3.5A so less drain on battery. Hope this helps.
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Whilst it is possible to drive a microwave off a 12 volt battery serviced by a solar system, it introduces some massive challenges to do so in a caravan. They simply draw too much power for a modest installation as discussed here to provide.
You would need a large inverter, most likely a second battery, and a lot of sunshine.
As said it is possible but for most not that practical. Some enthusiasts have done it, but it is definitely real enthusiast territory.
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We’ve seen posts here, from people claiming to run microwaves from inverters, and I’ve posted to ask for a description of their setup: But none have ever responded. Consider supplying a microwave oven which will draw around 1,500 Watts (twice it’s heating power) from a 12volt source. That’s over 120Amps. Or four times your domestic cooker’s rating.
We have a 12v TV but no longer use it, preferring to stream onto an Ipad, or occasionally a portable computer (Mac Air) on the few occasions that we watch TV. As for a solar panel keeping your battery topped up, we spent 4 weeks off grid with a 120W solar panel, without any difficulty, last June. We also have a small inverter for charging the laptop and occasional printer use. It’ll just about power my travel hair straighteners, so I normally use a catalytic gas one. We also have a 12v hair dryer, but it works best in the car with the engine running.
So if you forget your power hungry TV and microwave, you’ll save yourself a lot of money and won’t be giving up much in Summer. Dark winter evenings in front of the Tele, with microwave meals might be better served with EHU.
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Many thanks for all the replies, looks like a freestanding 100w panel will work but we should get a 12v TV and live without the microwave, Cheers
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The price you quote is low. For 100 watts I would expect to pay over £200. Beware of poor controllers. We have a 90 watt that cost £200 some years ago and I found the voltage control wasn’t good. I now only use that panel in winter or rainy summers.
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In respect to the TV, it does not need investment in a 12 V DC one.
If what you have is modest in size and of quite modern technology, it should as used in a caravan draw a low amount of power, albeit with requiring a 240V AC input.
For that 240 V AC it can be powered by an inverter, we did for a decade power a SONY 15" that way.
Important here is the quality and the power rating of the inverter used.
It is pointless and potentially energy wasteful as well as costly to use one way over the size needed. Plus some TVs might need the more refined "pure sine-wave" type as opposed to the "modified sine-wave" more budget type. The SONY worked on one modified sine-wave inverter I have but not another, though I used a pure one for our caravanning. The inverter I used is 150 Watt and was well suited and probably still a bit over sized. It was about 90% efficient, so whilst not quite as power frugal as a dedicated 12 V DC TV might be, it was what we had and using it carried very little penalty.
If a friend has a small inverter, even the cheaper modified sine-wave, it would be useful borrowing that to try and see if that model was adequate and the TV ran on it without issues.
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The price you quote is high for solar panels. I bought a 150w panel for £130 3 years ago. I had a 120W semi flexible panel delivered to me yesterday. It cost less than £100. The situation is different for folding panels with the controller included on the back these are more expensive. I agree with your comment about controllers btw.
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JENNY, I have, I think, explained my system many times on here. I am one of those, in fact perhaps the only one, who uses a microwave through an inverter. Let me deal first with the OP. When I set my system up back in 2013, I had two brand new 110ah batteries (or so I thought) , a 2000w pure sine wave inverter and a 135w SP fixed to the roof. My SP is still there and working well. In the first couple of years the system worked very well and kept us in power at 100% virtually all the time but as with lead acid batteries, the capacity ie - the amount of power the battery can actually hold started to diminish and that affected the usefulness of the heavy draw items like the microwave and toaster and the inverter alarm came on more frequently as the batteries became older. Now, it has to be said that the batteries I bought were Elecsol- a defunct make and not a good battery at all as they were on their last legs as a company at that time and were producing nothing but starter batteries! However, they performed well for two years but then dived to little more than keeping the lights and pumps working. It was time to change. As I am a confirmed off gridder I changed the two heavy lead acids for a 100 Lithium and have had no issues since. If I were starting again, I would certainly look at the biggest power output SP it was possible to fit and the comment by Boff regarding the ‘suitcase type’ certainly has gravity. 100w is OK for summer use I would say but winter use? I’m not sure I would want to go for more than a long weekend but then if the skies are bright and sunny, again, you would get more power to the panel. The sun is low in the sky in winter so the capture of light is much less. And it’s not just the size of the SP- the capacity of the storage is just as important. That’s why batteries are so important to the success of the operation. It’s not good having a panel that is producing oodles of power if there’s nowhere to store it and the opposite is true- it’s no good having massive capacity if the SP is struggling to supply it- it’s a balancing act and it has to be thought about. My general rule of thumb is that 120w is the absolute starting point for anyone seriously considering off grid camping. My next van will certainly be upgraded to at least 150w but more likely 200w.Having been to the show yesterday and seen RVs with 300w on the roof- now that’s getting somewhere! Now to deal with the use of kit on board. A DECENT leisure battery and more usefully, 2, are capable, without damage, of supplying large amps for short periods. I would never for instance, try to cook a meal in the microwave or heat something that took 20mins or so (not with a lead acid/s anyway) but I do use it successfully for things that take 3 mins or so. ie a toaster-3-4 mins, Vacuum 3- 4 mins etc. The television at 30w will hardly touch the battery and the ALDE pump at just over 1 amp will hardly put a drain on the battery. The idea is not to kick the backside out of the battery but use it well within its capacity. I won’t talk about the Lithium as very few have them and they can’t be compared to a lead acid. But with the right setup, you can use microwave and toaster on an offgrid caravan. If you are saving anything between £10 and £25 a night on site fees, that money can be used to fund the equipment needed. So yes, install the correct equipment and offgrid caravanning can be perfectly possible in winter but as in everything, don’t expect the world from a 100w SP and 1 battery as you can’t get a quart out of a pint pot.
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Footnote! If anyone wants to know more about offgrid caravanning and Lithium batteries, which, although Initially expensive, can save you money over a longer period, Roadpro at Daventry have now produced a very good guide which covers all aspects of Caravanning offgrid. It answers all the questions that are usually asked about this subject. Called ‘The Roadpro Guide to Lithium Batteries for Motorhome, Campervans, Caravans, Specialist Vehicles and Boats’ I highly recommend you get a copy( if you’re going to the show, pick one up,) or if not, ask them to send you one,.
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I have a lower tech approach to off grid than Merve. The caravan is fitted with a microwave. At home our microwave is used 99% of the time for either heating milk for my wife’s coffee and cooking veg, maybe the occaional ready meal. In the van off grid. The milk is heated in a pan that cost about £2. The veg is cooked in a steamer that cost me nothing. I do have an old inverter that I used to use for a camera battery and my laptop. I know have a 12v battery charger for the camera which leaves the laptop. Phones, iPad (multiple) kindle are all charged from 12v usb.
If there is an ehu I will plug in. Unless it is raining or I, generally can’t be ar$ed for an overnight stay.
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"If you are saving anything between £10 and £25 a night on site fees, that money can be used to fund the equipment needed."
Something of a big "if" in savings, just for giving up an EHU. Using a totally different type of campsite is also needed. The more realistic saving without just taking an EHU, lays between £3>£5.
We are very long term caravanning solar panel users, I think our first was in 1991 and involved making the suitable controller. We remain great fans of it, plus almost exclusively in the UK camp without an EHU but do so for the site options that brings.
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Something of a big "if" in savings, just for giving up an EHU. Using a totally different type of campsite is also needed. The more realistic saving without just taking an EHU, lays between £3>£5.
Sorry Ocsid but I maintain that the savings on sites can be and are substantial. Sites I have visited have saved me at the very least £8 a night and many are saving me more than that. As for the sites , yes, that’s another draw for me- quiet, uncrowded CLs, grass pitches and peace! But it’s not all about saving and sites for me- it’s also about paddling my own canoe and the fun I find in doing it. As Boff says, one can do it in a low tech way and there’s nothing wrong with that but that extra margin of comfort now we are approaching our latter years is really helpful. The kit is bought and paid for and will soon be moved to my new ‘van (NEC 2019!). I have never said I won’t hook up again but I can’t see me doing so. The technology keeps improving and it offers opportunities to caravanning families only dreamt of before.
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The great thing about modern technology is that it offers opportunities that hitherto, have not been possible. Yes; most certainly one can go off grid at the ‘bucket and chuck it’ level or choose any level of comfort right up to being able to use microwave; toaster, virtually unlimited tele ( if that’s your bag) and being able to run the heating pump without much worry of running out of power. The further you go or to put it another way, depending on what facilities you want, you have to match your kit to your requirements. Ocsid is absolutely right when he says it’s enthusiasts territory but what is an enthusiast? I would argue that you don’t have to be a massive enthusiast to get the pleasure of offgrid camping. I started very meagrely and it was good fun and very little difficulty. I have built up from there. These days I want a little more comfort so I am prepared to align my system with that in mind. Modern tech allows you to do that. Quality Solar Panels, as not all of them fulfil the promises- I would always go for monocrystalline as they are better than their poly cousins: A search of the web will very quickly start to reveal what panels are worth having. Inverters are the same, always buy one well within the capacities you are going to ask of it. ie. if you are going to run something requiring 300w and that is the maximum you will ever ask of it the a 600w inverter will be excellent -then you have to decide Pure sine wave or Modified sine wave: However, if like me you are wanting to run microwave and toaster, a 2000 or 3000w PSW inverter will do the business nicely. Going back to the 300w kit- and again, Boff is spot on with this, a decent size (90-110ah) in GOOD ORDER will be able to cope. However, with the larger amps 2 batteries will be required and even then, can only be used with care due to the tendency of plates to warp if you try to kick the backside out of them. So, we move to Lithium. This is a totally different animal to the lead acid and has so many advantages. It can produce massive amounts of power when asked without any danger of damaging the battery- unless of course you are not taking any notice of your battery monitor and run it down to nothing!! Then you could have a problem but the BMS (battery management system) will shut down the power before you get to that stage- technology again comes to the rescue. The one thing I always try to explain is the importance of a ‘balanced’ system. In other words, make sure your panels are capable of recharging your batteries fairly quickly or as fast as the weather will allow. Tiny Sp - big battery- no good as is large SP- small battery. Yes, I agree wholeheartedly with you Ocsid- it can be enthusiast territory but I’ve had so much fun doing it!! And I will, hopefully, well into the future, now the kit is there and with the battery having a life of 20 to 25yrs along with the SPs and the inverter- savings every year will pay for that kit well within 25 yrs. One thing is for certain, if I was in my 30s or 40s and I could afford it, I wouldn’t hesitate on finding out about the opportunities modern tech offers and installing a system whatever level that might be.
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For the benefit of others Merve can you start putting some real numbers and costing up for this microwave powering solar system?
- The price of that 3000 Watt PSW inverter?
- The size and pricing of that associated panel matching lithium technology battery installation, offering 25 years life? [How many have achieved that 25 year life so far?]
- The size, pricing and weight of the solar array to quickly recharge the battery system?
- The price of the solar controller required?
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Hi Ocsid. You ask a relevant question but you will know that there are dozens of different panels , inverters, batteries and controllers. Putting a price on it is difficult or well nigh impossible as it really depends on what one wants to get out of a system. My system I put in 6 yrs ago I remember the SP being around £550 for 135w. Massively cheaper now as you will see. The two lead acid batteries were £100 each and the controller came with the Panel. The inverter was £340. However, over the last 6 years, the system has paid for itself a couple of times over. I still have the panel working very well, the inverter, although not top quality, is OK for what I need. You live and learn and the more I have gone into this , the more I have learned about systems and what is on the market.
Now, I have a new van arriving in April and part of the offer was for them to fit a 100w panel and supply a tow cover. Tow cover is fine but the 100w panel will have to be substituted for a 310w which they have agreed - the cost- £319.99! and that is for a panel that is almost 19% efficient. Such a massive difference- down to a quid a watt now! The panel weighs 18kg but as I have taken 2 lead acids out weighing around 70kilos for the two, I am still way under where I was weight wise. So, so far it hasn’t cost me anything you could argue. The Lithium Battery will be moved into the new van. That cost around 1k but they will become cheaper as more and more people start to use them. The inverter, although OK, will be changed for one that does what it says on the box. It will be pure sine wave and rated at 2000w- plenty big enough to do everything and handle everything I want to use. (The old one will be sold.) The new inverter will be around £400 with a 350 watt MPPT controller with a Lithium cycle as is necessary. That is around £140. The only other bit of kit that I need to correctly charge the Lithium from the engine is the wildside Battery to Battery charger. Again with a Lithium cycle. That’s another £180. So we have about £1,700 worth of kit that can be moved easily from van to van and that has a life expectancy of 25yrs. We tend not to change our vans very often so that helps- we won’t be reinstalling the system every 2or 3 years! The panel can be moved too but that is a little more difficult but certainly possible. So, we tend to do about 60 nights away a year at the moment and, I save on average about £9 -£10 a night on site fees. If we want to talk about CAMC sites, you can double that or more. But let’s stay with CLs and the £9. That’s £540 a year at the moment- we will be increasing our time away very shortly and as we increase, so do the savings. Not only that, I now have the freedom to go to any site I like on the network. I have the freedom to use equipment I could only dream of a few years ago. It all makes for a super easy time away. Don’t forget that this is only on the electric side of things. If you talk about LPG Safefill is another huge saving to caravanners like me but I had better be quiet about Safefill- some don’t like me mentioning it! Now, if you extrapolate that figure by 25 you can see that it’s not what you pay at the beginning which I would be the first to admit is not for the faint hearted but I take the long view and the savings are massive. It’s the same as the Lithium- bloody expensive to start with but cheaper than lead acid in the end. It’s just how you view things I guess. I just like the idea of wild camping- I think it catches the essence of what caravanning is all about but being able to have a proper coffee or being able to use a toaster is just heaven! If I was to look for another reason, it’s greener than using electricity created by burning the dinosaurs! I hope I have put some clarity to the question you ask. Speculate to accumulate- Yes, you can spend quite a bit but then you can save much more than you spend.
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Thanks Merve. So your solar system is a bit over £2000, but could answer the OP's request for powering a microwave. I notice you have not gone for the 3kW inverter settling for a 2kW, presumably this being adequate to power the microwave.
Item Price in £
Panel Array 320
Solar Controller 140
Battery 1000
Inverter 400
DC to DC converter 180
Total 2040Without the need to power these very high demand units I suspect most needs at todays costings could be answered whilst retaining the van's typical £100 conventional battery, and adding a 100Watt £100ish panel and a £50 odd controller? Just a £150 additional investment.
The massive cost increase being predominantly driven by the likes of the microwave and because of the abuse of LA battery technology that brings, the desirability to adopt a Lithium technology there.I do find the 25 year life arguments less than convincing, initially that they can only be predictions and secondly it needs an abuse free life. Any inadvertent running down to a low state of charge has a life limiting issues even here.
I suppose also I have reservations based on the poor real world life I have had with the lithium technology used in my laptops and smart phones. Here, a usable life of about three years, leaves me not to be over confident about the claims of 25 years, though I realise there are a spectrum of differing lithium technologies.
Without the abuse of say a microwave, my LA batteries have never given less than 8 years usable life, so spending on three of those consecutively to yield the 25 years, is much cheaper than going lithium for me, at today's prices.
Finally, in this time of fast advancing technology I am far from convinced I will be wanting to be "holding in" with my 25 year old today's best kit investment, that far ahead.
Getting another 25 years is for me an idle dream anyway, it would come caravanning with our letters from the Queen hanging up in the van though!1 -
Ocsid, thank you for your comments. Yes, one can power a microwave using a lead acid and a large enough inverter but it will have a damaging effect on the battery. I can drill a hole into concrete using a normal drill bit but I’ll not be able to use it again- had I used the correct masonry bit for the job I would have been able to drill lots of holes if needed! Large draw on a lead acid will warp plates etc and shorten the life of the battery drastically. I found this out to my cost- I had 2 x 90ah batteries and they were fine for the first 2 years but that was it! I needed new batteries. I could have spent £400 on two new LA batteries which, I now know are damaged under conditions that I would use them or go Lithium and get rid of the worry.
Yes, a 2000w inverter will handle everything I need with the microwave drawing about 70 amps or so. I can’t see the point of buying a bigger inverter if the capacity of a 2k inverter is well within the zone you ask it to operate. A pure sine wave stops all the fears associated with modified sine wave.
A Lithium will supply this amperage without damage and it can be recharged quickly again without damage. As for the 25yrs longevity of the Lithium- let’s just agree to disagree. Neither of us can prove or disprove, all I can say is that I have researched this quite heavily as you can imagine and I am more than impressed by the abilities of a Lithium Battery. With 1000s of cycles- and I mean thousands- proved by people who have tested these batteries for months and months, Manufacturers have tested them to destruction and from these tests, real facts emerge. I tend to believe the unbiased evidence produced. I have to say that these Lithium Iron PHOSPHATE batteries are completely different to the batteries found in phones tools etc and they are suffering from the problems that some Lithium Iron batteries have had in the past. You talk about real life situations- that’s why the battery is surrounded by clever electronics- these electronics will shut the battery down if there is a problem therefore protecting it from damage. However, you do accept that there are different Lithium technologies. Life4Po batteries are safe! Inside a caravan untouched and unmoved I can’t see that any abuse will occur. No fumes, no acid, no maintenance, and 1/2 the weight. - always something the caravanner is aware of
I can’t comment on how you use your batteries or battery but I would suggest that you use it for lights and pumps-? - hardly a stress for even a lead acid. The fact is that a Lithium is more economical to buy if you want the full fat usage of your caravan. It leaves a LA battery on the start line as it breaks the tape at the end of the race! The term’ it’s like wild camping with hook up’ is very true. It’s not just the microwave though, and let’s not get hung up on the microwave , it’s everything else I want to use on board and in the awning. My awning lights for instance light the awning like daylight on the darkest of nights and draw 4 amps. No problem for a Lithium, the toaster vacuum and to a lesser extent the blender all require high amps- again, no problems with a Lithium.
We will see if the 20- 25 yrs life span comes true- well, perhaps I, like you will not get that far but I will have had a wonderful time trying these technologies out - but I am glad to be in a position where I can start to prove the next generation of technology in a practical and real life situation. My goodness, I wish I was 30 again- the technological future is very exciting. The price, as in all relatively new technologies will inevitably drop and I think Lithium will become commonplace in years to come- unless another technology comes along which is better and I’m perfectly able to accept that as possible. I will keep the forum informed as to progress. The one thing I can say is by using the microwave, I am using something that I bought anyway!! And why use gas (even if it is from a Safefill) if the sun has filled the battery and to make 4 rounds of toast it uses 8% and no damage to the battery. The 310w panel will charge the battery much faster after a heavy draw- and carry on the good work the 135w has provided over the past 6 years.
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Just as a footnote, A LA battery or batteries, linked up to a decently sized solar panel are perfectly capable of keeping you off grid as many have found. Lights and pumps take very little power and even our Avtex only uses 30watts. A small inverter of say 150 watts can run one or two appliance which don’t require much power. Horses for courses!!
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I was pondering fitting another battery box in the floor of the MH garage to accommodate a second battery, preparatory to getting an inverter to run the microwave off-grid. However, given your comments on the punishment this would give a LA battery, I think I'll give up on that idea. I'm too long in the tooth to justify shelling out for a Lithium based setup.
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Have you seen the EZA system by RoadPro? Cyber? When I started, I had 2 x 90ah batteries and the inverter I have now. I had no idea at the time that repeated heavy discharge of LA batteries is detrimental to them. It can warp the plates etc. They worked fine for Two years and to be fair, they were not of good quality as I later found out. One lives and learns. However, AGM LA batteries are better adapted to the task but are still not the full answer. Research on the web told me that if I wanted to do what I had set out to do, Lithium was my only real choice. It’s a long term thing but I reckon at £500-£600 a year saved on going EHU - it’ll be money well spent. If I last 3 years the kit will owe me nothing and there’ll still be at least 17 yrs at least of useful service in the kit I have. I’m taking the gamble because I love the thought of living off grid and so does the OH. And as I have said before, it opens up so much more in the way of out of the way sites- something we love. In 2017, because of the non EHU situation with me, we were able to go on holiday with my daughter and SIL, and their 2 boys. (Plenty of power for showers!) We all had a wonderful 15day holiday in fabulous weather - £60! And that was purely because I was non EHU. Just an example of what can be achieved.
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Bit of an eye-watering price tag and at my age, hard to justify. Apart from a quick burst for a microwave, I'd also need prolonged power to recharge the E-bike batteries. I'll need EHU even if only every four days or so.
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When we bought our van I asked for a second battery to be fitted, which they did. The fitted it behind the main battery, continental van battery under a seat. To get to this battery I had to disconnect the main battery, which left the terminals live. Unscrew four screws so that I could lift the electric control box out of the way remove main battery, drag slave battery out disconnect that. Then do the whole thing in reverse to fit a spare battery. First time I did it to almost an hour mainly in the dark. What a palaver.
I have modified this I have made the rear battery the master battery. The front slave battery is connected to this with a fused cable Anderson connectors and quick release clamps. It now takes less than 5 minutes to drop in a battery. If necessary I could take the depleted battery to a pub garage house, where I am sure for a few beer tokens they would recharge it. In reality the only time the batteries are depleted apart from operator error is when we are off ehu for 5 nights at new year. All other times the solar panel copes well.
For me at the moment lithium ion batteries are just not cost effective. But if you are interested I suggest that you waste /spend a couple of hours looking, on you tube, at some the rigs and equipment that our colonial cousins use when they go Boondocking (spl!)
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