Solar verses batteries

[hilldweller]

Any help or advice would be much appreciated.

The secret of electricity is to use as little as possible. Get that right before you start to add batteries and solar. Have a look on your TV for the wattage and see if a new TV, which is quite cheap, could reduce this a lot.

We used to get 3/4 days out of a single battery. Now with a single battery and solar we run indefinitely in the summer.

It is marginal if we use our electric bikes a lot.

 

[hilldweller]

I have two 110amp leisure batteries and a 120 amp solar fitted
Norman.

Just to be accurate it's 120W. Which means about 10A midday on the equator. Average for a real world day will be more like 5A. You have 220Ah of battery so 110 / 5 = 20 hours (ish) for a full charge and we don't get 20 hours sunshine. You need more solar to match the batteries.

Put another way your total energy input is that 120W ( much less in the real world ) so if you use more electricity then your batteries go flat no matter how big they are.

Batteries are heavy. Heavy is bad.

So I'll put my money on two panels and one battery. We have one battery and one panel now and survive.

Let's put it another way, your hosepipe delivers 5l per hour for 10 hours a day, you've got 50l a day.

Your tank is 100l, it will take 2 days to fill it.

You use 75l a day, insisting on lots of showers.

Day 1 100l. You use 75l. Your hose puts in 50l. End of day 75l stored.
Day 2 75l............................................................................50l stored.
Then 25.
Then 0. At this point you realise you can't have all those showers or you need another hosepipe.

 

[TUCANO]

Brian,

Luckily for me I prefer to strip wash, and you are correct, typo error, meant to say 120 amps.

Thanks ,

Norman.

 

[TUCANO]

DAMN DAMN DAMN 120 WATTS

 

[pappajohn]

I have two 110amp leisure batteries and a 120 amp solar fitted,

Norman.

typo error, meant to say 120 amps.

Norman.

Same typo again.....

You mean 120 WATTS

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[tjay]

Hi, I have 3 x 110 amp batteries fitted plus a 120 watt solar panel on the roof on her new motorhome. My question is, will the one solar panel be enough to charge my batteries ??
Btw all the lighting inside/outside are L.E.D.'S

Thanks in advance

 

[scotty1]

Trikeman iwonder what the result would have been without the solar panels and doing 3hrs driving every couple of days ?

 

[scotty1]

Hilldweller well done thats the sort of tech data that i can understand thanks.Scotty

 

[scotty1]

Because we very rearly stay in one place more than 3 nights and then hook up i think the 2 battery is the way to go,we wont know untill we try.

 

[funflair]

I would go for 100 ish watts of solar just to keep the batteries as full as possible as it should help with longevity not being stood half charged with plates sulfating/sulphating.

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[Sidney]

went to our local motorhome dealerto ask how much to have a solar panel fitted to our warwick duo ended up coming out having ordered 2x110 amp batts fitted instead.they have had to order low profile batts to fit under seats ( passenger one swivels) .Their advice because ileave it on hookup when in storage at home.when we are away we only do two or three nights wild then find site with hook up to recharge.est £450 inc parts and labour ?

I'm ready to be shot down but I'd say that your dealer isn't far off the mark. You leave it on hook-up at home and only spend 2-3 days on the trot without a EHU.

Fitting two big batteries will deliver what you want. Putting a solar panel on your roof would be visible (being a van conversion), increase drag (with associated wind noise a reduced fuel economy) and mean making another hole in the roof.

Cost? Well you can shop around and you might save some money but its not a rip off at £450.

 

[Neilfg]

Question: If you have a solar panel, drive around and it is sunny will the batteries get the benefit of solar and the alternator charge whilst driving?

 

[maxine and jo]

yes

 

[TheCaller]

Question: If you have a solar panel, drive around and it is sunny will the batteries get the benefit of solar and the alternator charge whilst driving?

Yes - probably.

How effective it will be will depend on how the two are wired & what other control systems you have installed.

If both the alternator & the solar panels are feeding through something like an Electrobloc, then yes.

If the solar panels are wired directly through a third party controller to the battery, bypassing whatever control system is installed, there is a potential for the two control systems to confuse each other, resulting in one or other system supplying less than its maximum charge capability.

It depends how each system senses that the battery is fully charged. Let's say the day dawns with weak sunshine. There is enough sun for the solar controller to start the charging process, but not enough to produce much current. The solar controller will output what current it can at its charging voltage - somewhere in the 13.6 - 14.4V range, depending on both the controller & the battery state of charge.

Then you start the engine & the alternator starts to feed power the the existing on board control system. That control system sees not the 'no-load' battery voltage, but the charging voltage produced by the solar controller. It has no idea that the solar controller exists, so can be fooled into thinking that the batteries are already fully charged, so it scales back what it takes from the alternator. The result is that all you get is whatever the sunshine can produce, losing out on what the alternator could generate.

What do you have in the van already?

 

[Neilfg]

What do you have in the van already?

The current van has solar I do not think though that this is wired into the Electroblock, it has a Battery Master which was fitted at the same time as the solar and 2 new batteries, the current setup seems to work fine and we have no real issues with it (we've not drained batteries). We are changing van the new one will come with 2 batteries and an EBL220-4 but no solar, we will look to add solar probably a 140-150w panel, am starting to think about how to add it.

My question just came from the thought that our usage is quite similar to the OP, and our panel tops the battery up but probably not fully but with a drive included every 2 days or so I wondered whether they do work together.

Is there an easy way to find out, if they (solar and alternator) conflict or if they work together?

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[Lenny HB]

The current van has solar I do not think though that this is wired into the Electroblock, it has a Battery Master which was fitted at the same time as the solar and 2 new batteries, the current setup seems to work fine and we have no real issues with it (we've not drained batteries). We are changing van the new one will come with 2 batteries and an EBL220-4 but no solar, we will look to add solar probably a 140-150w panel, am starting to think about how to add it.

My question just came from the thought that our usage is quite similar to the OP, and our panel tops the battery up but probably not fully but with a drive included every 2 days or so I wondered whether they do work together.

Is there an easy way to find out, if they (solar and alternator) conflict or if they work together?

Shouldn't need a Battery Master if you have an Elektroblock as the have their own circuity that allows the leisure battery to charge at a higher rate similar to a Battery Master, with an Elektroblock it is always best to use a Schaudt solar regulator then the engine battery will be charged as well, also avoids problems when on EHU, some models of Elektroblock shut down when on EHU if a solar regulator has been connected direct to the battery.
When driving there shouldn't be a problem as the solar output is likely to be quite low and the alternator will take priority.

 

[TheCaller]

We are changing van the new one will come with 2 batteries and an EBL220-4 but no solar, we will look to add solar probably a 140-150w panel, am starting to think about how to add it.

For a single panel, or for multiple panels wired in parallel, connect to the Electroblock via their own solar controller - the LR1218 or the latest, more efficient MPPT LRM1218.

That will avoid any conflicts. Your existing van should really have been done this way.

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[Reallyretired]

Bear in mind that in most cases the amount of charge put into the leisure battery(s) by driving is pretty little. Obviously a B2B charger will make a huge difference, but most motorhomes seem to have the wiring between alternator and leisure battery long and thin so the charge is very little.

B2B charger will cost similar or more than solar.

 

[Neilfg]

the LR1218 or the latest, more efficient MPPT LRM1218.

This is very helpful, will now spend some. time on research.

 

[tonyidle]

No it won't.!!!!

To put back what you used the night before may take an hour or more running to replace depending on your power demands and the state of discharge.
An almost flat battery could take all day.

Definitely would take all day. And part of tomorrow.

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[tonyidle]

For a single panel, or for multiple panels wired in parallel, connect to the Electroblock via their own solar controller - the LR1218 or the latest, more efficient MPPT LRM1218.

That will avoid any conflicts. Your existing van should really have been done this way.

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Conflict is the wrong word. However many systems you have charging (or attempting to charge) the battery at the same time the result will be the same: the system outputting the highest voltage at the time wins. If that particular system can't supply the current being taken by the battery the next lower voltage system will assist. Multiple charging systems won't all add together to charge the battery more quickly but neither will any one of them prevent the maximum available charge charging it as quickly as possible.

 

[mjltigger]

I'm going to disagree with all you very knowledgeable people .. I charged a fully flat (flourescent light wouldn't turn on) leisure battery and a fully flat engine battery (had to jump start, wouldn't turn over at all just a click) and 3 smart mobile phones and a kindle between here and folkestone.. that's about 3 hours. When I say charged I mean leisure battery still green the next morning after a night in an Aire and engine started on the nail when I turned the key.

Unless you're using an inverter to watch tv all night I think you should be fine without the solar.

 

[robnchris]

Just to be accurate it's 120W. Which means about 10A midday on the equator. Average for a real world day will be more like 5A. You have 220Ah of battery so 110 / 5 = 20 hours (ish) for a full charge and we don't get 20 hours sunshine. You need more solar to match the batteries.

Put another way your total energy input is that 120W ( much less in the real world ) so if you use more electricity then your batteries go flat no matter how big they are.

Batteries are heavy. Heavy is bad.

So I'll put my money on two panels and one battery. We have one battery and one panel now and survive.

Let's put it another way, your hosepipe delivers 5l per hour for 10 hours a day, you've got 50l a day.

Your tank is 100l, it will take 2 days to fill it.

You use 75l a day, insisting on lots of showers.

Day 1 100l. You use 75l. Your hose puts in 50l. End of day 75l stored.
Day 2 75l............................................................................50l stored.
Then 25.
Then 0. At this point you realise you can't have all those showers or you need another hosepipe.

Brian your SO Money Supermarket.......

Excellent explanation....

Our new motorhome is so frugal on power usage, all led lights, we have an Avtex tele with is low power usage, have one 110amp battery and one 120 watt solar panel we get by just fine.

 

[colinw]

Brian your SO Money Supermarket.......

Excellent explanation....

Our new motorhome is so frugal on power usage, all led lights, we have an Avtex tele with is low power usage, have one 110amp battery and one 120 watt solar panel we get by just fine.

Music to my ears Rob ( or Chris ) , hoping to hit a britstop this weekend !

 

[maxine and jo]

Solar needs heat as well as light an the UK is the best for aether sooooo it oranges and lemons but i do agree with TheCaller in all he has said a man of solar!

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[colinw]

Solar needs heat as well as light an the UK is the best for aether sooooo it oranges and lemons but i do agree with TheCaller in all he has said a man of solar!

Think you might get a lot of comments on that one !

 

[mpdcymru]

I should add re the above, when we first started motor homing, we toured the UK, staying on caravan club or camping and caravan club sites, we were members of both. Nowadays we are members of neither, it was expensive to pay the membership fees, then to use their sites it was about £25 a night. Touring France, Belgium, The Netherlands and Germany using an ACSI card we pay 13 Euros a night sometimes less. I don't know why is so expensive in the UK, we have stayed on French municipal sites for 5 Euros a night with hook ups. The sites aren't luxurious, no swimming pools or bars etc. but basic is ok the facilities are clean and you get a warm welcome, and in my experience you get free wifi that you can actually use. I've met Brits on these sites who think the caravan club and the camping & caravan club have priced themselves out of the game, a view I now share. And the wifi you have to pay for on UK sites never works.

We are still members of the caravan club and I agree that their prices are far too high, so much so that we do not use their sites very much. The only reasons we continue our membership is their CLs and European travel service which we often find useful.

On the odd occasions we do try to book the sites are very often full - which gives the reason they are still making high charges = they can and people will still pay it!

 

[maxine and jo]

One last thing on this i would like to say on the side of solar is it will reduce the the frequency you will need to change your batteries

 

[TheCaller]

There are so many different systems out there, put together is so many different ways, then used in so many different ways, that it's not surprising that people's experience varies so much.

Some systems will work perfectly happily together, each supplying what they can. Other people have reported problems, with one system appearing to interfere with another.

The impression I get from other's feedback is that dumb systems work quite well together, because they know nothing & just get on with doing their thing. It seems to be the more intelligent systems that are reacting to false impressions created by other systems in parallel.

 

[scotjimland]

Solar needs heat as well as light

I think you are getting mixed up between photovoltaic panels and thermal solar panels..

photovoltaic solar panels, the type under discussion, only use UV light .. in fact heat is an enemy of efficiency ..

thermal solar panels absorb heat..to raise the temperature of the circulating water..

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