Roof solar is just a waste of money….

D

dawsey

Joined
Apr 24, 2018
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2001 Hymer B544
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Contentious, yes I know. I can almost hear the cries of derision and snorts of laughter… :)

But - the firm conclusion we have come to after living in the van through four seasons on the continent, is that for any camper, roof mounted solar panels are actually near-useless and are just a waste of money IF you have a decent B2B and can hook up, and you do actually routinely use some power via a decent Invertor as we do.

Hear me out….

First - our setup. I wanted us to be self sufficient. No need for hookup as we’d be full timing in France through winter with few campsites open, so staying on free aires. I installed as many panels as I could fit onto the roof. This was 600W of roof solar (6x100W) connected in parallel, combined 25/50A MPPT and B2B, 200ah of Lithium and 2000W hard-wired invertor, all integrated with the existing Schaudt Elektroblok systems. Van is a 21yr old Hymer A class. The only change to the standard vehicle electrical architecture was an uprated alternator (150A) to ensure 80A could be delivered at idle.
All has worked perfectly for a nearly a year. The only part of the system which isn’t really useful, and actually just isn’t needed is all the solar panels. With a decent B2B, the solar panels are, in fact, not really needed at all.

So why is the roof solar useless?

Summer
Yes you can get great output from the panels in full sun. I’ve seen 27 Amps at 20V, 540 Watts. The 6mm CSA copper cables from the collector to the MPPT were actually getting hot. At one point I was just about able to run the similar rated power a/c unit just from all that lovely solar power.
But - it’s really not a good idea to park a van in full sun in a continental summer. It heats up and we couldn’t get it cool enough to sleep until midnight, running a high power extractor continuously. So you seek out shade. We would always park in the shade of a nice big trees to AVOID direct sun on the van. Then, of course the solar panels give very little, my 600W gives about 50W even with the clever MPPT system. The panels, in shade, become effectively useless.
With a 50A B2B, you only need to run the engine for 10minutes to put the same amount of charge into your batteries.

We found that when parked in the shade we could never get sufficient charge even from our huge roof mounted solar array to recharge our batteries. After four or five days they would be discharged, just a couple of days more than in winter…

If wildcamping/free car park/aire with no EHU, even in summer we still fully discharge our batteries and had no choice but to run the engine or drive to the shops.

If on paid aire or campsite it’s just better to park in the shade and plug in EHU (you can run engine to recharge batteries and save the EHU cost but you may well consume more diesel than the hook up cost!)

Winter - usually on free aires

The sun is always so low that there is almost no effective charging, but the electrical energy use is higher (lighting, being stuck inside more etc). The panels contribute so little it is laughable. If not moving every couple of days, if no EHU you have to run the engine. We got in the habit when stationary of running the engine for up to an hour every day just after nightfall to both recharge the batteries and help the van build and retain sufficient warmth for the night. The solar panels in full sun would give a peak of maybe 4-5A on a very clear winter day, but you would have to be completely out in the open and nowhere near a building or a tree. In reality, the low sun was usually obstructed by trees or buildings and we averaged maybe 1-2A during the short day. Conclusion, in winter, our solar panels were absolutely useless.

When driving, a good 50A B2B will so rapidly charge lithium batteries, it again rendering the solar panels pointless. There were many times when we drove for an hour and it was cloudy so I would isolate the solar (which might have been giving 5A) to make the integrated MPPT/B2B auto switch from 25 to 50A just to charge faster.

Conclusion - if you have a powerful B2B, and you do actually make use of an invertor and consume some power using 240V appliances (yes I know this isn’t everyone..) then heavy roof mounted solar for a camper is just not worth the money as it really is effectively useless, summer or winter. It’s way better to park in the shade and connect EHU summer, and, if no EHU is available, in winter you will find that you have to run the engine every day no matter how many panels you might have (you also benefit from all the lovely engine heat, so little is wasted).

Looking at our experience, I concluded that the only way to get real utilisation and power out of solar panels in a continental summer without turning your van into a dutch oven is a collapsible suitcase/remote panel set up, where you can set up and arrange a remote array of panels and point them toward direct sunlight, with the van remaining safely parked in the shade. This would work, but of course you’d need the space, so you are really limited to campsites.

Right, I will get my popcorn…… :)
 
Last edited:
Recently did 4 nights on a temporary holiday site. No ehu. Didn't want a generator, didnt want to run the engine, didnt want to go for drive. Solar did just fine. If I used your argument there would be loads of times it doesn't work. There's enough times it does work to justify it. It also keeps my batteries charged when the van isn't in use. You seem focused on when it doesn't work. You missed out it doesn't work in the dark. 😀
 
It all depends on how much 12v you use..

If living full time I can see issues arising, for us 'leisure' users, our solar works all year for our needs.

People who proclaime that solar 'is useless' simply because it doesn't suit their particular needs, are doing no one any favours.

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Solar has worked fine for us for 14 years, summer and winter, but most we have been off grid is a week. We use it every night for John's CPAP and at the moment only have 1 leisure battery. But then we were the same when one failed and we didn't realise till we couldn't get the diesel heating to work all night.
 
dawsey said:
Contentious, yes I know. I can almost hear the cries of derision and snorts of laughter… :)

But - the firm conclusion we have come to after living in the van through four seasons on the continent, is that for any camper, roof mounted solar panels are actually near-useless and are just a waste of money - IF you have a decent B2B and can hook up, and do actually need to use some power.

Hear me out….

First - our setup. I wanted us to be self sufficient. No need for hookup as we’d be full timing in France through winter with few campsites open, so staying on free aires. I installed as many panels as I could fit onto the roof. This was 600W of roof solar (6x100W) connected in parallel, combined 25/50A MPPT and B2B, 200ah of Lithium and 2000W hard-wired invertor, all integrated with the existing Schaudt Elektroblok systems. Van is a 21yr old Hymer A class. The only change to the standard vehicle electrical architecture was an uprated alternator (150A) to ensure 80A could be delivered at idle.
All has worked perfectly for a nearly a year. The only part of the system which isn’t really useful, and actually just isn’t needed is all the solar panels. With a decent B2B, the solar panels are, in fact, not really needed at all.

So why is the roof solar useless?
Summer
Yes you can get great output from the panels in full sun. I’ve seen 27 Amps at 20V, 540 Watts. The 6mm CSA copper cables from the collector to the MPPT were actually getting hot. At one point I was just about able to run the similar rated power a/c unit just from all that lovely solar power.
But - it’s really not a good idea to park a van in full sun in a continental summer. It heats up and we couldn’t get it cool enough to sleep until midnight, running a high power extractor continuously. So you seek out shade. Park in the shade of a nice big tree. Then the solar panels give very little, my 600W gives about 50W even with the clever MPPT system. The panels, in shade, become effectively useless.
With a 50A B2B, you only need to run the engine for 10minutes to put the same amount of charge into your batteries.

We found that when parked in the shade we could never get sufficient charge even from our huge roof mounted solar array to recharge our batteries. After four days they would be discharged, just one day more than in winter…

If wildcamping/free car park/aire with no EHU, even in summer we still fully discharge our batteries and had no choice but to run the engine or drive to the shops.

If on paid aire or campsite it’s just better to park in the shade and plug in EHU (you can run engine to recharge batteries and save the EHU cost but you may well consume more diesel than the hook up cost!)

Winter - usually on free aires
The sun is always so low that there is almost no effective charging, but the electrical energy use is much higher. The panels contribute so little it is negligible. Even if not moving, if no EHU you have to run the engine, and we would do it anyway to help the van achieve sufficient warmth for the evening. The solar panels in full sun would give a peak of maybe 4-5A on a very clear winter day, but you would have to be completely out in the open and nowhere near a building or a tree. In reality, you might average 2A during the short day.
In winter, solar panels are absolutely useless.


Conclusion - if you have a powerful B2B, and you do actually make use of an invertor and consume some power using 240V appliances (ultra I know this isn’t everyone) then heavy roof mounted solar for a camper is just not worth the money as it really is effectively useless, summer or winter. It’s way better to park in the shade and connect EHU summer, and just to run the engine in winter (where you also benefit from all the lovely engine heat, little is wasted).

Looking at our experience, I concluded that the only way to get real utilisation and power out of solar panels in a continental summer without turning your van into a dutch oven is a collapsible suitcase/remote panel set up, where you can set up and arrange a remote array of panels and point them toward direct sunlight, with the van remaining safely parked in the shade. This would work, but of course you’d need the space, so you are really limited to campsites.

Right, I will get my popcorn…… :)
Click to expand...
You really are into windups aren't you, this is better than your first.
 
I think youre overpowered on the Solar front.
We have 370 watts of solar for 200 ah of lithium and were heavy users of the electric on our last German holiday in the height of summer.
We also aim for shade but couldnt work out (when in full view of the sun) why we were getting so little electricity coming back in. It was because we only had 150 working watts of solar, (Maximum yield was 121 watts) and yet we got sufficient to fully charge 2 electric bike batteries each day (Up to 80 km of use each). We did use free electric from ladestations and tankstelles en route, where available) but all that did was allow us to go up to Turbo if we wanted and just boost the batteries a little (and we would have a beer whilst getting the free leccy). Charging the 2 batteries would take 8-10 hours per night and we were nowhere near an empty battery.
I cant believe (I could be wrong) that you are heavier users of electric than us and have never had to resort to turning the engine on.
We move on every couple of days so that helps and suspect we would struggle if permanently parked up in the shade.

The issue is permanently parking up in the shade. What you need is to park it on a campsite where you can decide which trees have to come down in order for morning sun then afternoon shade. If only ..... ;)
 
I did read it all ;) and I have to agree "solar doesn't work for you" dawsey but of course we are all different, when we travel on the continent we are usually on Aires or Stellplatz and although sometimes we have the option of EHU it certainly isn't always, in the UK we are very often on rallies or temporary holiday sites and there is no option of hook up, we use very little gas as we make full use of our 3kw inverter for boiling the kettle and cooking, OK we could survive for 5-6 days on our batteries alone but then would need to drive for about 6 hrs to be charged again, as it's only 1hr back home this trip we would then have to plug in at home, as the sunshine is free (after paying for panels) then it seems silly not use this option, If I were to spec another van it would have more solar not less.

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Solar works great for us as we rarely use EHU, my B2B died & I've not missed it so didn't bother to replace it. We hate parking in the shade we love full sun.

Next van if it ever arrives will be getting as much solar as I can get on the roof, it's cheap these days for the return you get.
 
To a degree you are correct...
But then we're very heavy users and due to roof space only have 300w of solar. We're going to get rid of our never-used dish and use the space for new (more efficient) bigger panels.
It's very seldom we're at the same place for more than two nights - pretty much only at shows. At the end of a cloudy-rainy weekend we're down to around 30% of our 280ah.
But we avoid shade unless it's only for a day or so.
 
Extended running the van engine at idle speeds is not recommended for a modern diesel engine.
That said, I worked near an Ocado delivery warehouse and they would routinely have 100 customer Mercedes delivery trucks parked up, but running to keep the fridge running for the cooled area on the back where deliveries are stored. 🤷‍♂️
Mike.
 
If you consume large amounts of power (Air Con, Kettle, Toaster, Microwave, TV etc) I agree 'normal' amounts of solar is useless.
If you travel every day it's probably uneccesary too.

However, we did 10 days at Le Mans 24 hour race completely off grid powerwise. 300 watts of solar. Never came near to running out.
Charged mobile devices and laptop computer via 240v inverter. Also charged up electric bikes via inverter. Lights, fans, music etc. Wife used hair dryer every few days.
So it depends - you want to be a high power user you need mega solar/Lithium or EHU but for 'normal' economical users it's fine.

I wouldn't want to be parking near someone who is starting their engine to charge their battery all the time.
 
dawsey said:
Contentious, yes I know. I can almost hear the cries of derision and snorts of laughter… :)

But - the firm conclusion we have come to after living in the van through four seasons on the continent, is that for any camper, roof mounted solar panels are actually near-useless and are just a waste of money IF you have a decent B2B and can hook up, and you do actually routinely use some power via a decent Invertor as we do.

Hear me out….

First - our setup. I wanted us to be self sufficient. No need for hookup as we’d be full timing in France through winter with few campsites open, so staying on free aires. I installed as many panels as I could fit onto the roof. This was 600W of roof solar (6x100W) connected in parallel, combined 25/50A MPPT and B2B, 200ah of Lithium and 2000W hard-wired invertor, all integrated with the existing Schaudt Elektroblok systems. Van is a 21yr old Hymer A class. The only change to the standard vehicle electrical architecture was an uprated alternator (150A) to ensure 80A could be delivered at idle.
All has worked perfectly for a nearly a year. The only part of the system which isn’t really useful, and actually just isn’t needed is all the solar panels. With a decent B2B, the solar panels are, in fact, not really needed at all.

So why is the roof solar useless?

Summer
Yes you can get great output from the panels in full sun. I’ve seen 27 Amps at 20V, 540 Watts. The 6mm CSA copper cables from the collector to the MPPT were actually getting hot. At one point I was just about able to run the similar rated power a/c unit just from all that lovely solar power.
But - it’s really not a good idea to park a van in full sun in a continental summer. It heats up and we couldn’t get it cool enough to sleep until midnight, running a high power extractor continuously. So you seek out shade. We would always park in the shade of a nice big trees to AVOID direct sun on the van. Then, of course the solar panels give very little, my 600W gives about 50W even with the clever MPPT system. The panels, in shade, become effectively useless.
With a 50A B2B, you only need to run the engine for 10minutes to put the same amount of charge into your batteries.

We found that when parked in the shade we could never get sufficient charge even from our huge roof mounted solar array to recharge our batteries. After four or five days they would be discharged, just a couple of days more than in winter…

If wildcamping/free car park/aire with no EHU, even in summer we still fully discharge our batteries and had no choice but to run the engine or drive to the shops.

If on paid aire or campsite it’s just better to park in the shade and plug in EHU (you can run engine to recharge batteries and save the EHU cost but you may well consume more diesel than the hook up cost!)

Winter - usually on free aires

The sun is always so low that there is almost no effective charging, but the electrical energy use is much higher. The panels contribute so little it is negligible. If not moving every couple of days, if no EHU you have to run the engine. We got in the habit when stationary of running the engine for an hour every day with the heater in full power about 6pm to help the van build and retain sufficient warmth for the night. The solar panels in full sun would give a peak of maybe 4-5A on a very clear winter day, but you would have to be completely out in the open and nowhere near a building or a tree. In reality, you might average 2A during the short day. Conclusion, in winter, solar panels are absolutely useless.

When driving, a good 50A B2B will so rapidly charge lithium batteries, it again rendering the solar panels pointless. There were many times when we drove for an hour and it was cloudy so I would isolate the solar (which might have been giving 5-10A) to make the integrated MPPT/B2B auto switch from 25 to 50A just to charge faster.

Conclusion - if you have a powerful B2B, and you do actually make use of an invertor and consume some power using 240V appliances (yes I know this isn’t everyone..) then heavy roof mounted solar for a camper is just not worth the money as it really is effectively useless, summer or winter. It’s way better to park in the shade and connect EHU summer, and, if no EHU is available, in winter you will find that you have to run the engine every day no matter how many panels you might have (you also benefit from all the lovely engine heat, so little is wasted).

Looking at our experience, I concluded that the only way to get real utilisation and power out of solar panels in a continental summer without turning your van into a dutch oven is a collapsible suitcase/remote panel set up, where you can set up and arrange a remote array of panels and point them toward direct sunlight, with the van remaining safely parked in the shade. This would work, but of course you’d need the space, so you are really limited to campsites.

Right, I will get my popcorn…… :)
Click to expand...
This just doesn't warrant getting involved with you again, this is absolutely bull shit where your other was half believable.

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BouncyBoatFolk said:
Extended running the van engine at idle speeds is not recommended for a modern diesel engine.
That said, I worked near an Ocado delivery warehouse and they would routinely have 100 customer Mercedes delivery trucks parked up, but running to keep the fridge running for the cooled area on the back where deliveries are stored. 🤷‍♂️
Mike.
Click to expand...
The "idling" issue could be a relic from the old days when cylinders would glaze causing increased wear and damage to rings (due to unburnt fuel becoming carbon).
As I understand it, not a problem since the 90's.
....I'm not an expert at engine wear, just something an old mechanic told me. So feel free to correct me :smiley:
 
RogerIvy said:
The "idling" issue could be a relic from the old days when cylinders would glaze causing increased wear and damage to rings (due to unburnt fuel becoming carbon).
As I understand it, not a problem since the 90's.
....I'm not an expert at engine wear, just something an old mechanic told me. So feel free to correct me :smiley:
Click to expand...
I'll correct you, it is a huge problem & the easiest way to wreck an engine. Moden diesels never get up to operating temperature idling from cold which can do a lot of damage to the engine.
Even worse you will destroy the CAT & DPF which will be very expensive.

Modern diesels should be driven straight off after starting this allows them to get up to operating temperature quickly.
 
Just back from another visit with the wife to our local hospital, every ambulance outside as usual Merc, Fiat, Renault had their engines running on idle all day. It wasn't so much the harm to the engines I was concerned about, it was the cost of the diesel being used to keep the occupiers in the front cool.
In the winter they have their noisy diesel heaters whirring away to keep them warm, which I guess there is no alternative for as they have to be comfortable for the net patient that might well be in shock.

So I have come to the conclusion, that once the engines have reached full working temperature, there cannot be that much harm in sitting with them on idle, especially if they have B2B's charging on board batteries, air con units to run.
LES

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TinaLes said:
So I have come to the conclusion, that once the engines have reached full working temperature, there cannot be that much harm in sitting with them on idle, especially if they have B2B's charging on board batteries, air con units to run.
Click to expand...
Agree not a problem, also their drivers don't pay for the repairs.
It's the idiots on Sites & Aires that start them up from cold and leave them ticking over that wrecks them.
 
Lenny HB said:
I'll correct you, it is a huge problem & the easiest way to wreck an engine. Moden diesels never get up to operating temperature idling from cold which can do a lot of damage to the engine.
Even worse you will destroy the CAT & DPF which will be very expensive.

Modern diesels should be driven straight off after starting this allows them to get up to operating temperature quickly.
Click to expand...
Thanks - and I agree with all you said
.... but to the idea that idling causes cylinder glazing ... is this still a thing or not (or never has been)?
 
RogerIvy said:
Thanks - and I agree with all you said
.... but to the idea that idling causes cylinder glazing ... is this still a thing or not (or never has been)?
Click to expand...
Only glazing issue I'm having is my eyes .... 😄

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Probably still the same issue, not reaching their correct working temperatures leads to deposits adhering to the cylinder wall that harden and glaze. The glaze is detrimental to long engine life.
Mike
 
Lenny HB said:
Solar works great for us as we rarely use EHU, my B2B died & I've not missed it so didn't bother to replace it. We hate parking in the shade we love full sun.

Next van if it ever arrives will be getting as much solar as I can get on the roof, it's cheap these days for the return you get.
Click to expand...
In two years we have made 474Kwh👍
 
:snooze::snooze::snooze:....


Lenny HB said:
I'll correct you, it is a huge problem & the easiest way to wreck an engine. Moden diesels never get up to operating temperature idling from cold which can do a lot of damage to the engine.
Even worse you will destroy the CAT & DPF which will be very expensive.

Modern diesels should be driven straight off after starting this allows them to get up to operating temperature quickly.
Click to expand...
I'm not saying your wrong Lenny, but our 2018 Sprinters at work (17 of them) are left running for an hour or so every morning after they've been loaded with food trays to keep the Freezers at temp.

So far we've not had any DPF or CAT issues.

Cheers
Red
 
Lenny HB said:
I'll correct you, it is a huge problem & the easiest way to wreck an engine. Moden diesels never get up to operating temperature idling from cold which can do a lot of damage to the engine.
Even worse you will destroy the CAT & DPF which will be very expensive.

Modern diesels should be driven straight off after starting this allows them to get up to operating temperature quickly.
Click to expand...
I think I might have mentioned this before.

We have a modern diesel Jag. During lockdown (after the first couple of weeks) I received a note from Jaguar saying to run the engine for 30 minutes with the A/C thermostat set at 22C. And each following week, to run the engine for at least 15 minutes with the same A/C setting.

Now I don't claim to be a particular expert on the subject, but it would be surprising if Jaguar were recommending such action for its vehicles if it was going to wreck the engines? :unsure:

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