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Solar panels retro fit


laimeduck

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With the higher charges being introduced for EHU I am considering whether it would be worthwhile to install/have installed, more solar panels to my 20 year old old Benimar. At present we have one panel of 20 yrs vintage, installed when the van was converted which I guess is about 80Watt? (it measures about 80 x 60 cm?) I have no documentation on this at all, and it is all controlled via the Benimar master panel on which I have no info other than the photo. It still works OK and keeps both leisure and motor batteries topped up during the year. (We don't plug in to EHU unless we are away in the van).

Can anyone give me an indication of what would be required in terms of equipment and cost, to update the van so that we could happily survive( and enjoy ourselves) off grid? 

I am looking for estimates of solar panels and installation. Controllers and installation, etc.

In any replies please bear in mind that I can wire a plug and resolder a connection, and am aware that v=ir, but that is about it! If you talk too technical it will go straight through my ears!
There will I am sure be many more questions!

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Jeremy,

the Benimar panels of that vintage were (ISTR) 55W (maybe 50), and after 20 years the efficiency is probably down a bit.

Going completely off-grid means losing 230v capability. If you need that then things get a bit more complicated. If you simply need to be self-sufficient with 12v, then things are somewhat more simple, though any solution will depend on the nature of your consumption.

Managing the consumption (e.g. with LED lights) can make a big difference, (as can a second leisure battery). We're relatively light consumers, and I could survive most summers adequately with my 120W panel.

A bit more detail on your requirements/usage?

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My 2019 van came as standard with a 120w solar panel which became defective so I decided to replace with three panels giving me 290w.

I found:-

1. could not use the existing cable as it did not have the voltage/current capability (can't recall the detail!) so I had to run a new cable from roof to the controller.

2. panels need to be matched or efficiency will be lost - see this video https://www.youtube.com/watch?v=OsOnDmPSwqA

3. MPPT controller needed to be upgraded

So I tore my (remaining?) hair out for a while but it was worth it.  Huge increase in solar power generated (x3) and I would do it again

 

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4 hours ago, Robinhood said:

Jeremy,

the Benimar panels of that vintage were (ISTR) 55W (maybe 50), and after 20 years the efficiency is probably down a bit.

Going completely off-grid means losing 230v capability. If you need that then things get a bit more complicated. If you simply need to be self-sufficient with 12v, then things are somewhat more simple, though any solution will depend on the nature of your consumption.

Managing the consumption (e.g. with LED lights) can make a big difference, (as can a second leisure battery). We're relatively light consumers, and I could survive most summers adequately with my 120W panel.

A bit more detail on your requirements/usage?

I am rarely inclined to disagree with statements made by @Robinhood, but I do not see why that should be so.  In fact I believe that a former forum member installed an inverter and custom switching on his now elderly Burstner.  If my memory is correct the details were discussed on this forum.  I believe that some loads e.g. mains charger, were only supplied via EHU, but other items could be powered via an inverter.

I have recently looking into fitting a solar panel to my PVC, but as our style of MH use involves almost daily driving, with consequential adequte ngalternator charging, I am having difficulty in justifying the time commitment.

What re-awoke my interest was the appearance of 300W panels measuring 1410 x 700mm, which would be a tight fit lengthwise in the available space on our PVC roof. Priced at under £150 on eBay, very tempting. Along with the time consideration, I was not too happy when I discovered that four apparently separate vendors all had the same VAT registration number???

Alan

 

Edited by Alanb
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Alan,

my comments about 230v capability were simply aimed at the fact that providing it (via an inverter) adds somewhat to the complication of the solution.

Providing additional 12v capability is (IMO) relatively simple. Adding substantial 230v off-grid capability, whilst far from impossible, requires considerably more thought and design (particularly around capacity and wiring).

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4 hours ago, Robinhood said:

Jeremy,

the Benimar panels of that vintage were (ISTR) 55W (maybe 50), and after 20 years the efficiency is probably down a bit.

Going completely off-grid means losing 230v capability. If you need that then things get a bit more complicated. If you simply need to be self-sufficient with 12v, then things are somewhat more simple, though any solution will depend on the nature of your consumption.

Managing the consumption (e.g. with LED lights) can make a big difference, (as can a second leisure battery). We're relatively light consumers, and I could survive most summers adequately with my 120W panel.

A bit more detail on your requirements/usage?

Robin thanks ....... fair comment.

We tend to use our Mabel on A) 2 major trips to Europe, May and September for 6 to 7 weeks each. Plus B) since covid we have done a few one to 2 week trips in the UK. 

For A we have generally stayed on sites eg ACSI or municipal, and more recently Camping Car Park, and for B on sites or pub sites. 

We are finding now that for A on many occasions ACSI sites are fully occupied and there are undoubtedly fewer of them generally,  and for B) many are eyewateringly expensive!

So it would be good to not have to rely on a site with EHU.

We currently use the fridge freezer on 240, Hot water on 240, and cook on a 2 ring small 240. We charge our electric bikes on 240, and the built in charger plus exiting solar panel keeps our 2 x 100Amp hour leisure batteries charged.We also use the gas oven and hobs 4 rings. Generally we do not use heating, but have a small 1kwatt fan heater for emergencies. We have no aircon (just opening windows!) No TV. We dont use the on board shower. Other small electric items are electric razor, toothbrush and phone chargers.

When I say "off grid" I don't mean so called wild camping.....it would simply be nice not to have to rely on having to find a site with EHU.

Jeremy

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Jeremy,

I'd interpreted "off-grid" much as you describe.

I have to say that if you envisage using 230v as you describe provided entirely by solar, I think you are going to be "challenged". I suspect most people with similar aims would use gas for most of the purposes you describe. An inverter could provide 230v capability, but such a capacity would be, ermm difficult.

I'm currently on an excellent Stellplatz in the Hunsrück in Germany, where the overnight charge is €10 but the electricity is metered at ¢70 per kWh. 

I have refillable gas bottles (currently wide availability in many countries even if reducing in the UK) so choose to use gas for most purposes where elec is expensive or on the meter. (I like to run the fridge on electric, but if metered I can isolate the battery charger and let the solar do it's job if I avoid gas - which is generally cheaper anyway). The fridge is on elec, everything else is off the battery (not being 230v charged - only solar and via alternator).

If you're looking for cost-effective solutions, I think I'd be installing refillable gas (or a hybrid bottle solution involving a bottle from the visited country, see Brian Kirby's approach). For the small items, 12v USB charging for phones, and a low-wattage (plugin) inverter for razor and toothbrush.

E-bikes are a specific and difficult issue.

I've recently gone lithium, with my original AGM batteries being 5+ years old. It was largely done for weight-saving (best part of 35kg for equivalent capacity). I was informed that my van could cope with it as a drop-in solution (albeit not 100% efficient), but I've replaced the charger and added a b2b, and the battery is far from challenged, but no inverter.

 

 

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Without major upgrades you can forget about heating, cooking, hot water, and fridge/freezer, from batteries. I guess you have these covered by gas anyway, your small gadgets and bike batteries can be charged via an invertor, as one devise is a toothbrush, this will need to be a 'pure sinewave' invertor, a smaller invertor 'should' have less loses, so don't go big on one.

We have a 85w panel and smaller batteries but get by from late spring to early autumn, for charging the bike batteries we charge little and often, but this would depend on how much you take out of then, we rarely use more than 100Wh per bike per day.

Edited by colin
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Everything and anything is possible but just because you can do it does not mean you should do it said somebody once……

Our real world experience is that you need to really understand what you need your system to do (& I use the word need rather than want intentionally) before you even start to think about what you need to buy. A really good off grid system that will allow you to run indefinitely would be around 400W of solar, 2-300Ah of LiFePO4 battery and a 2-3000W pure sine wave inverter. Add in a 30-50A DC-DC charger and you’d have a really good system, especially if you only stay a few nights and then move on. For hot water and some cooking you’d still need gas but this would run a decent coffee machine and charge your e-bikes etc as well as maybe run an induction hob.

100W of solar and a 100ah of lead battery with a small 1000W inverter will get you by but you wouldn’t be able to charge your e-bike and you’d be pretty much bereft of 240V except for very short periods.

Our system is 230ah of LiFePO4 battery, 230W of solar, 30A combined DC-DC/MPPT charger and a 2000W pure sine wave inverter. We run our coffee machine whenever we want and a compressor fridge which stays on all the time as well as the bosses hair dryer and/or tongs (whatever they are🤔😜) and other bits and pieces of 240V stuff and we have never managed to get below 60% battery capacity. For hot water and heating we use gas and are now looking at installing an underslung tank. We tend to only do a maximum of 4 nights before moving on and I can’t remember the last time we used EHU. We use lots of the various clubs rallies and temporary holiday sites and rarely spend more than around £10-12 per night as well as (usually free) pub stopovers in between rallies etc.

Work out how you plan to use your van going forward then design a system to meet your needs, there is always an element of compromise but you can have everything you need without spending an absolute fortune. Our set up cost us less than £1k by shopping smart. I built the battery myself, the solar panels were bought when heavily discounted by the supplier, the inverter was found on Gumtree and the DC-DC/MPPT charger was found locally on Facebook marketplace. Everything (except the battery) is from Renogy. You can buy cheaper stuff (but don’t) and you can buy more expensive stuff but our experience with Renogy has been only positive.

Hope this is helpful

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Thanks all for your replies. 
You have confirmed what I suspected. 

On another forum many seem to have upped their solar to around 300-400 watts, and say they can survive for days without EHU. No one has said how much it cost them to achieve this. (My 78 year old sister has just gone down the solar route for her house and it will be 15-20 years to reach break even!)

I wondered exactly how cost effective going down the solar route would be for the number of days and way we use the van. 

If, as puddlejumper has said, it cost him about £1k to get a usable system (and he obviously knows what he's doing!), then for me it would probably cost much more. 

We do have a small inverter (250watt) which we use when driving to power a 60watt crockpot, so that would be OK for the smaller items.

I believe there is also the possibility of using fold- up solar panels via some sort of power pack/controller that can then be plugged into the van's EHU. At the moment I'm in Spain and can't find the link to that info, but will chase it up. Sounds interesting. No surgery to the van!
In summary, bearing in mind the age of the van, the costs involved and the surgery that would have to be made on the van, I think we will continue to use sites and Aires with hook ups. I'd be quite content with metered EHU's and pay for what we use.


Jeremy
 

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1 hour ago, laimeduck said:

We do have a small inverter (250watt) which we use when driving to power a 60watt crockpot, so that would be OK for the smaller items.
 

As I posted the tooth brush will most likely need a pure sinewave invertor as they usually use inductive charging, unless that is it's USB powered, in which case a decent car phone charger will suffice, so you need to check, we use a 300w charger for the bike batteries, pretty much everything else is charged via a Tronsmart USB-C

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56 minutes ago, colin said:

As I posted the tooth brush will most likely need a pure sinewave invertor as they usually use inductive charging, unless that is it's USB powered, in which case a decent car phone charger will suffice, so you need to check, we use a 300w charger for the bike batteries, pretty much everything else is charged via a Tronsmart USB-C

Colin thanks .... to be honest I'm not too fussed if the toothbrush doesn't charge ....we'll revert to good old-fashioned arm/wrist power!

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17 minutes ago, laimeduck said:

Colin thanks .... to be honest I'm not too fussed if the toothbrush doesn't charge ....we'll revert to good old-fashioned arm/wrist power!

I'm guessing the razor has a socket that lead plugs into, and not inductive charge like most toothbrushes? 

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To be fair, with a decent MPPT solar charger and 200w of solar panels and a big enough battery reserve, say 200ah of lead acid battery, you should be able to stay off grid pretty much indefinitely during the summer months so long as you don’t want to use too much 240V. I think your issue will be charging your e-bikes but without knowing how much power the charger takes it’s hard to give a more specific answer.

We saw it as an investment in our van, we mainly use rally sites and THSs at an average cost of £12 a night. Most sites are at least £25 a night (& often a lot more). This year we’ve done 87 nights up to now and have spent nearly £1150 on pitches. If we’d stayed on sites we would have spent at least double that so the way I look at it our set up has paid for itself in less than a year. We used a similar set up in our old van and spent over 350 nights away in that and that probably saved us in excess of £5k. Could we have done it cheaper? Definitely. The issue for us was always about having the confidence. It’s a bit like range anxiety with an electric car, our set up just removes all the worry about not having enough charge in the battery for wherever we are. I’ve even disconnected the on board battery charger because we just don’t need it. The only time we use EHU is on the very rare occasion we stay on a site and it’s included in the price, if they charge extra for electricity then we simply don’t use it.

If you share the details in your eBike charger then I’m more than happy to make a suggestion on how to get what you need as cheaply as possible. The only other advice I would give is do not go to a main dealer caravan place and ask them to supply and fit everything. Get them to fit it by all means but source the parts yourself, you will save a lot of money. Our friends were quoted £1150 to supply some solar panels and a charge controller by our local dealer. I did a bit of shopping around and got them bigger and better kit for £385 delivered to their door. They’re nicknamed main stealers for a good reason, find a decent local independent guy, it’ll save you a fortune.

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Puddlejumper thanks for that. Picture of the current e- bike charger. The bikes are now about 10 years old and we are maybe looking to upgrade in the near future.

There are two e-bikes so two chargers.

As far as fridge freezer are concerned we could easily either use gas or not use it or even use freezer blocks when not on ehu for a couple of days. So I'd not want a stonking big inverter.20240923_172259.thumb.jpg.9fdaba44ba554784d10f3542c88f2114.jpg

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7 minutes ago, laimeduck said:

Puddlejumper thanks for that. Picture of the current e- bike charger. The bikes are now about 10 years old and we are maybe looking to upgrade in the near future.

There are two e-bikes so two chargers.

As far as fridge freezer are concerned we could easily either use gas or not use it or even use freezer blocks when not on ehu for a couple of days. So I'd not want a stonking big inverter.20240923_172259.thumb.jpg.9fdaba44ba554784d10f3542c88f2114.jpg

That's the same output charger we have, as we only use 100wh per day, and then not every day, we put each battery on charge for a maximum of 1 hour in morning, with our 85w panel we are marginal, next van will be looking at 200w of panels.

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Hi Jeremy,

We had our solar updated last year on our nuevo.

It came with a 80w panel which ran through the Sargent solar controller, to be honest it wasn't a lot of use.

we took it to RoadPro in Daventry, they left the 80w panel just to charge the V battery and added a 105w panel and three 25w panels all joined together, they done it this was to get as much solar on the roof as possible, they also fitted a MPPT controller.

once the L battery has charged it then charges the V battery.

On a bright sunny day both batteries are charged by about 10am and on a dark overcast day by late afternoon

The cost was around one thousand pounds, the results so far are very good, we spent two nights off grid last week and the lithium never dropped bellow 13.3v and V battery bellow 12.6 and at least one day and night we didn't move the van at all  

Pete

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7 hours ago, laimeduck said:

Puddlejumper thanks for that. Picture of the current e- bike charger. The bikes are now about 10 years old and we are maybe looking to upgrade in the near future.

There are two e-bikes so two chargers.

As far as fridge freezer are concerned we could easily either use gas or not use it or even use freezer blocks when not on ehu for a couple of days. So I'd not want a stonking big inverter.20240923_172259.thumb.jpg.9fdaba44ba554784d10f3542c88f2114.jpg

So that charger is going to be drawing around 40A from your battery while it’s running so with a 100ah lead acid battery your battery would be down to about 50% SOC (state of charge) and effectively flat in just over an hour. A decent 200W solar set up would possibly put in around 4-5A per hour on a decent sunny day. If you have two of those I would really want to be looking at a 2-300ah LiFePO4 battery. The other option is to put a decent DC-DC (often known as a B2B) charger of around 30A and you could then have your engine running to charge at around 30A while you’re eBike batteries are on charge.

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11 minutes ago, Puddlejumper said:

So that charger is going to be drawing around 40A from your battery while it’s running so with a 100ah lead acid battery your battery would be down to about 50% SOC (state of charge) and effectively flat in just over an hour. A decent 200W solar set up would possibly put in around 4-5A per hour on a decent sunny day. If you have two of those I would really want to be looking at a 2-300ah LiFePO4 battery. The other option is to put a decent DC-DC (often known as a B2B) charger of around 30A and you could then have your engine running to charge at around 30A while you’re eBike batteries are on charge.

NO, that charger will not draw 40A, it will draw around 8A.

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Sorry but I think you may be mistaken. As the voltage drops the current goes up. While it may be charging at 48V the 240V will be coming from an inverter powered by the 12V set up so the inverter will be drawing around 40A from the battery.

Have a look at this converter online https://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html?srsltid=AfmBOorGjGSm_ePHDioLs8m4_rXSzeip2yiKRscuEetH8xj3fc31UJRB

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2 hours ago, Puddlejumper said:

Sorry but I think you may be mistaken. As the voltage drops the current goes up. While it may be charging at 48V the 240V will be coming from an inverter powered by the 12V set up so the inverter will be drawing around 40A from the battery.

Have a look at this converter online https://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html?srsltid=AfmBOorGjGSm_ePHDioLs8m4_rXSzeip2yiKRscuEetH8xj3fc31UJRB

I know that I only did electronics up to 1st year of HNC, but I do have a rough understanding. 😉

You have read a label and think you know what it means, that charger will draw around 8A, the clue for those who are not knowledgeable on these things is the output voltage and current which amount to 82w, for it to draw 480w (12x40) it would be expelling 400w of power which would give you a puddle of molten plastic. Somewhere on the forum there is a photo I took of a meter reading of the power draw of one of these chargers, I'm sure Derek could find it if you are a sceptic.

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Thanks to all who tried to help. I think probably the cost of installation of solar panels and controllers and additional wiring and batteries etc along with the cost of installing refillable gas systems etc rather negate the reason for doing this in terms of the amount of times we actually use the van and what we would save? Sounds like a few years for payback to me? ( And at my age time is probably the thing I haven't got!

I think I will be better off researching decent Camping car park/pub stops, small sites etc/and or paying for campsites for a few years!

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This week we should have been at a site with no EHU's, our 85w panel and 2x75ah batteries would be expected to just about keep up with our power demands. From october until late march we would expect to use EHU unless driving everyday.

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