Solar Panel Power

[BruceM]

You raise a good point. I’m still uncertain about our electrical generation requirement. Time to do some addition.

 

It’s likely that I’ll change the solar regulator for a dual charge unit that also provides some charge to the starter battery whilst the van is not in use.

 

For us there were two main attractions of getting a van, the convenience of taking breaks at short notice regardless of the weather and the ability to use it during the colder months – something we tend to avoid when we camp under canvas.

 

The van draws very little power – ie some LED lighting, tap pump and hot water so I suspect the existing solar might provide enough top up power during the summer months although we’ve yet to test that theory over a couple of weeks. We’re not interested in running a TV or other higher consumption devices.

 

Outside the summer season though we envisage using the heating and I suspect the Trauma hot air blower will make a significant dent in our residual charge.

 

So I guess my current aim get the solar into a state which, on paper at least, will meet our electrical needs throughout the year – although I suspect that the winter months will be a challenge too far with a panel that maxes at 44W.

 

 

[aandncaravan]

Bruce, You mentioned you were new to Motorhome ownership, so maybe you don't realise that if you intend to Motorhome at a time of year where you might need the Heating, it is likely even an ultra efficient 100w Solar Solution won't help you much?

 

In mid December the Sun doesn't rise until about 09:00 and it's dark by 16:00.

On a bright mid Winters day you will be lucky to average 1 amp for the 4 hours the Sun is 'high' in the sky, giving you a miserable 4Ah. 1Ah of which is likely to be nabbed by the Starter battery.

 

That is a typical, good Solar solution on a good bright day in the South. Head up to Glasgow and thick Cloud and you might lose half of that 4Ah?

You can see that even a 300watt Solar Solution is going to be of little value in those conditions.

 

You can supplement the Solar charge in Winter by 'planning in' short drives. But again bear in mind that the average good battery will take around 10 amps from the Alternator (It might rise to 20amps charge initially, but will drop back to a 10amp average within about 20 mins).

 

So if you consume 40Ah out of a 100Ah battery, you will need a 4 hour'ish drive to put that back.

The advantage of a twin battery setup in an example like this, is that if you take the same 40Ah from two batteries (20Ah from each), then each battery will charge back up in parallel with 10 amps to each battery, so 'only' a 2 hour drive is required.

 

It isn't quite that simple, and the figures rounded, but you get the idea.

 

 

So maybe factor in a EHU over night stop every 3 - 4 days?

 

Where Solar really scores is in the Sahara (the further south you go the greater the solar harvest) in June, where a 100watt Panel might harvest more than 90Ah a day.

Have a look at the chart on our solar panel webpage that shows the potential 25% difference in Solar harvest between Penzance and the North of Scotland on the same sunny day :

http://www.aandncaravanservices.co.uk/solar-panels.php

 

 

All the above shows the success of a setup will depend on many factors.

 

 

 

[BruceM]

Thank you - it all adds to the learning curve.

 

In determining my max power consumption I’d appreciate clarification on a couple of points.

 

My habitation unit electrical control panel displays current drain – see picture.

 

1. If with solar disconnected I turn on everything including heating, taps etc will the current drain displayed, lets say 5 amps, be the max usage achievable (excluding temporary add ons such as laptop charging)?

 

2. Does this meter show the ‘net’ current drain – ie if I do the same experiment during the day and solar is generating 3 amps should I expect the meter to display 2 amps net drain?

 

Note that the solar regulator is not connected in to the Electroblock EBL.

 

[aandncaravan]

The Meter is 'controlled' by the EBL, so all power going in or out of the EBL will be shown on the meter.

Any device connected directly to your battery, like a USB charger or Solar Regulator will not be reflected by the 'ammeter' needle as the EBL will be unaware of the draw or charge.

 

If the Solar Reg was wired correctly through the built in 3 pin Solar Port on the Elektroblock EBL then the total 5amp draw minus the 3amp Solar would result in just a 2amp deflection at the meter.

 

 

If you have a battery Master to maintain the Starter battery and it is wired in the 'usual way on an EBL 99', none of it's power draw, either from the Starter battery or the habitation battery, will show on the 'Ammeter'.

 

 

Tip : When you are 'loading up' the Solar panel to the max to assess its efficiency, then connect the Wattmeter between the Panel and Regulator.

When assessing/testing the Solar Reg, suggest you move the Wattmeter between the Solar Reg and the battery (or EBL if you move the regulator).

 

This way any differences in current between the two positions is easier to assign to the Solar Regulator. Remember like all 'Battery chargers' the Solar Regulator won't be 100% efficient (the worst can be less than 60% efficient) so expect a drop in the 'pure load' Solar panel, raw amps figure and that actually passed to the battery as a charge rate.

 

 

Does that make sense?

 

 

 

 

 

 

 

[BruceM]

Great, thank you. That makes absolute sense and fits in with what I suspected. I think I'm equipped now to determine my best and worst case power requirements and from that to take a view on the value of changing the solar panel which, as it’s riveted to the brackets that appear to be stuck to the van roof with silkafix, will not be a trivial job. The regulator I plan to change anyway to provide a dual charge.

 

 

[BruceM]

I’m planning to fit a fuse between the solar panel and regulator.

 

Is there any electrical reason not to fit a circuit breaker instead of a conventional fuse?

 

I’m thinking along the lines of something like this Link to eBay

 

[aandncaravan]

I have taken a couple of small low voltage breakers apart and was not impressed with the quality of construction.

A couple we evaluated had a 'sticky' action down to poor quality manufacture of the components which meant that the trip sometimes happened at much higher current than the rating.

But sometimes worked correctly.

You will note that the item you select on ebay, doesn't exactly have the tightest trigger tolerance.

 

The specifications for the unit in your link shows the following :

 

Rated Current: 30 A

Fusing Current: 30-50 A

 

A Fusing, or Trip trigger, current of 30 -50 amps is a heck of spread, in other words it might trip at 30 amps, or nearly 50amps!!!

 

 

We got ours on eBay and I suspected the units we bought on there were 'seconds' that had been rejected from a production batch.

 

Two of the types also used a solenoid that constantly drew power. When a certain power draw point was exceeded the solenoid operated and shut off the power.

That meant the unit was constantly consuming power from the Panel that never made it to the Battery.

It wasn't much, but in Winter 'not much' of 'exceptionally little' can be a lot.

 

The contacts were also very light duty, and I couldn't see them staying at their best for flowing current if the device was used as a 'switch' which is one of their 'alleged' advantages.

 

 

The disadvantage of a fuse is that it's a resistor which gives it's own issues when passing volts/amps.

Some fuses are so poor, like the not so quality Breakers, they also have varying 'blow points', but more importantly varying resistances.

 

 

But as this section of cable is the 'higher Voltage' side of typically 21v or higher, any voltage drop should make no difference to the overall power harvest.

 

If it was me I would use a Fuse Holder and quality Fuse.

You can see a Fuse and trust it is/will work, so long as the Fuse is quality,

 

As someone wrote on here recently KISx.

 

 

 

 

 

[BruceM]

Back on to the solar panel,

 

My Elektroblock 99 EBL has a solar regulator input (three pin – block 6) with a 10 amp fuse.

 

So by my reckoning, a 100W solar panel which at peak might generate 5.7 amps at about 18v, would after regulation produce 8.3 amps at 12v.

 

If this is correct then I suspect that wiring my solar regulator directly in to the EBL would mean that I can only use one 100w solar panel.

 

Is my conclusion correct?

 

Thanks.

 

[aandncaravan]

Yes and no.

You obviously have an early 16amp charger version of the EBL 99. If so treat it gently. Even when new it would only support a battery bank of 160Ah, and most are now 13 years + old. Remember it also charges the Starter battery as well so factor in an allowance for this as the Starter Battery is part of the total battery bank from the EBL 99 chargers point of view.

 

 

 

The later 18amp EBL 99 has a 15amp fuse in the Solar fuse holder. Schaudt state that this LR1218 and EBL 99 combination will handle 5 x 55watt panels..

I think the early EBL 99 PCB tracks behind the fuse will handle 15amps as well, but not guaranteeing that.

 

In your case, because it is such an old EBL 99, you might consider using the 2 pin Auxillary charger port as this is fused at 20amps. Pin 1 is the negative.

 

 

However, your figures are calculated at 12v, when 12v will not charge a battery. To charge a battery on Solar you want the highest voltage up to a max that the battery is designed for, like 14.4v.

 

If the battery is at 12.7v and the Solar output is 12.7v, no charge will take place even if the panel has '2amps available'.

 

 

 

We rarely see more than about 5 amps at 14.2v on a 100w Solar panel that is older than about 2 years, so will be surprised if your older panel can match that even with a better Solar Charger?

 

 

 

 

 

 

 

 

 

[BruceM]

Thank you. The more I find out the more interesting this gets!

 

The van is 14 years old so with the EBL probably being original your age related comments fit precisely.

 

I’ve just checked the batteries.

 

On the habitation side I’ve one at 100 Ah and one (retro fitted) 110 Ah, total = 210Ah

 

Then there’s the starter battery which is a big beast but with no visible Ah rating on it, it’s marked Yuasa European Calcium maintenance free but I suspect would be the standard Ah battery for a Fiat Ducato.

 

 

So conclusions (I’ll need some help with these) . . .

 

1/ On the face of it the EBL 99 will struggle to support this battery bank? (are we thinking blown fuse or smoke, and in what circumstances? – major discharge state?).

 

2/ In an attempt to future proof I’m debating whether to get a 165W or a 250W solar regulator, 250W being pointless if I were limited to one 100W panel. The exiting 100W solar panel will probably be replaced at some point and I might wish to add an additional 100W panel. Connecting via block 7 (auxiliary charging unit) would accommodate this as it would support up to 20 amp. Any downside of using this port rather than the dedicated solar port? I’m just trying to understand why the lower rated (10 amp) solar port would exist at all.

 

 

[aandncaravan]

1. . EBL 99 capability.

The limitation of the EBL 99 mains charger is only a limitation if you intend to use EHU when the batteries are around 50% or greater discharged.

It sounds like you intend to Free camp without EHU, relying primarily on Solar? If so then you will never use the mains charger so it's limitation is not an issue.

 

However, if the batteries do run low, and are not perfect, the load on the charger will be enough to fry it.

 

 

From experience when someone tells us the batteries are different size, different age, and especially if one is a 110Ah, it rings Alarm bells.

I strongly suggest you read our Website Battery Tech page, as just about everything with your battery bank seems to be what we advise against if you want to maximise every amp with reliability?

 

The batteries are just a storage vessel for the electricity, if you start of with the equivalent of a leaky old Water tank that only has a tiny pipe to squeeze in the Water, it isn't going to be the most efficient.

A poor battery bank can literally discard half the Solar you spend so much money harvesting

 

 

 

The Starter battery is likely to be a 90AH.

 

 

2.. On early versions of the EBL 99 the 3 pin Solar port was designed to work in harmony with a LR02 Solar regulator which could also use the 3 pin Solar port for wiring from the Solar Panel.

In other words the 3 pin port was both the Solar Panel connector to the regulator and the connection from the Solar regulator into the EBL. It was not a good solution and hardly anyone used it, so probably not worth trying to understand? Just explaining the history.

 

When the LR02/03 were dropped, the LRS 1214 came with a cable kit that allowed direct connection to the Starter battery for Solar charging and the 3pin Solar port became used solely for the Habitation battery.

 

 

With the EBL 101 onwards, the 3 pin port was wired so the centre pin gave access to the Starter battery, but this was back in 2006 when Solar panels were expensive and rarely fitted. Back then, a 100watt panel was considered 'big' and a 15amp rating sufficient for 270w of Solar. Late version EBL's have a 20amp capable fuse and I suspect the new units being developed will increase that further to 30amps..

 

Not using the 3 pin port on later vehicles/models can cause issues, but on the very early EBL 99 adopting the 2 pin port won't have any side effects.

 

 

If you are thinking of mixing very new Solar Panels with very old panels then it is likely that the very old panel might not have decent blocking diodes to prevent a more powerful, higher voltage Panel from turning the older Solar Panel into a Heater.

 

You can fit blocking Diodes, but they reduce the efficiency of the Panel. We would suggest you use the 3 pin Solar port for the old regulator and old Solar Panel and fit the new Solar Panel with a decent Duo Solar charger into the 2 pin port.

 

This new Solar Duo battery charger can then be used to charge the starter battery, but only go to the Starter battery if it is a Motorhome specific charger.

 

This will also allow you to monitor each panels efficiency as I suspect they will be quite different.

 

 

 

[BruceM]

Great, that explains a lot. I’d already poured over your excellent battery pages previously and was already getting twitchy about the current battery bank setup. A couple of Varta LFD90’s may be the direction I take.

 

The plan is to replace the solar regulator with a Votronic MPPT Duo. I’d remove and replace the existing '100W' solar panel rather rather than add to it and in doing so may increase to 200W.

 

I connect to the EHU at home so it seems that there’s a degree of EBL frying risk I need to take account of.

 

All that aside, a possibly philosophical question has arisen in my mind . . .

 

My inclination is to connect the solar regulator via the EBL 99 because it should be neater and, I understand, good practice. But in reality, what’s to be gained by it verses the alternative of connecting the solar regulator directly to the battery array and consequently bypassing the EBL? I appreciate that the current consumption meter in the habitation unit will not display the net current draw/charge but other than that what else would I be missing if anything? ie could my early EBL 99 be providing some additional functionality that I’ve failed to grasp?

 

 

[colin]

On previous solar set ups I've always followed 'best practice', but our present van has a set up fitted by dealer, this is definitely not fitted to 'best practice' but it does all we ask of it so have left well alone.

The controller is fitted at roof level as cable enters van and is connected straight to leisure battery.

Now here's a strange thing and maybe Andy can explain it, the solar panel appears to stop the cab battery charge dropping to low.

I'll explain, at home the van is parked under cover and the solar gets no direct sun, but gets enough light to give a very low charge for hour or so, this just keeps the leisure battery charged, and after 5 or 6 days the (poorly) cab battery drops down into yellow zone on the lt410 panel. but on site with plenty of sun the leisure battery gets fully charged which is to be expected, but even if the cab radio is used for say an hour every day or so the cab battery comes back up to charge (I think 12.7v from my poor memory) even after 5 days so maybe 4 hours of radio use it will be at 12.7v, very odd, it's as if the ebl is allowing some excess charge back to the cab battery, I can find nothing in manual which indicates the ebl acts this way.

[BruceM]

. . . and I may have answered my philosophical question whilst researching how battery chargers work – maybe someone can confirm/put me right . .

 

I’m thinking that the EBL 99 uses some kind of voltage sensing to determine when the habitation batteries are fully charged? So if the solar regulator is connected directly to the habitation batteries the EBL will be measuring the wrong voltage (during daylight) and undercharge the battery bank????

[aandncaravan]

BruceM - 2017-07-15 6:18 PM

 

. . . and I may have answered my philosophical question whilst researching how battery chargers work – maybe someone can confirm/put me right . .

 

I’m thinking that the EBL 99 uses some kind of voltage sensing to determine when the habitation batteries are fully charged? So if the solar regulator is connected directly to the habitation batteries the EBL will be measuring the wrong voltage (during daylight) and undercharge the battery bank????

 

 

 

 

There is no electrical disadvantage on an early EBL 99 going direct to the batteries, if you have an alternative method of showing volts and amps. However, using the Schaudt cabling makes it easier to hook into the Starter battery charge, but in your case that will be a very minor issue..

 

 

Many chargers use the voltage at the battery to decide the charge rate they adopt, so 'seeing' 14.4v Solar charge they may drop to a maintenance mode. Some use a combination of voltage and the current being drawn. Some like the Schaudt, use a pure timer, charging at full rate until the timer expires.

 

But I am struggling to visualise a situation where you would have both Solar active and be plugged in to EHU?

 

If you used EHU at home when the batteries are likely to be fully charged, the load on the EBL will be almost zero, even if you had 4 batteries.

 

Only if the batteries were heavily discharged and/or poor would the load be high. Even a 16amp EBL 99 can cope with two Varta LFD90's that are discharged to about 50% because they are so much more efficient than a conventional battery.

 

 

 

[aandncaravan]

colin - 2017-07-15 5:46 PM

 

On previous solar set ups I've always followed 'best practice', but our present van has a set up fitted by dealer, this is definitely not fitted to 'best practice' but it does all we ask of it so have left well alone.

The controller is fitted at roof level as cable enters van and is connected straight to leisure battery.

Now here's a strange thing and maybe Andy can explain it, the solar panel appears to stop the cab battery charge dropping to low.

I'll explain, at home the van is parked under cover and the solar gets no direct sun, but gets enough light to give a very low charge for hour or so, this just keeps the leisure battery charged, and after 5 or 6 days the (poorly) cab battery drops down into yellow zone on the lt410 panel. but on site with plenty of sun the leisure battery gets fully charged which is to be expected, but even if the cab radio is used for say an hour every day or so the cab battery comes back up to charge (I think 12.7v from my poor memory) even after 5 days so maybe 4 hours of radio use it will be at 12.7v, very odd, it's as if the ebl is allowing some excess charge back to the cab battery, I can find nothing in manual which indicates the ebl acts this way.

 

 

It is likely that the professional install, I won't say 'Dealer' as some dealers sub contract the work, uses a Steca style single battery Regulator with a Battery Master fitted to 'look after' the Starter battery.

The battery Master then steals power from the Habitation battery for the Starter battery.

This 'battery power theft' usually takes place when there is a greater than 0.75v difference between the two batteries.

A difference that usually results in the Starter battery being allowed to discharge too low, which then Sulphates shortening it's life.

 

 

I am guessing that when there is decent level of light, the Battery Master will 'see' the Habitation battery is being Solar charged and has risen above 14v. This creates a greater than 0.75v difference so the Battery Master starts up putting charge into the Starter battery.

 

In your situation when the vehicle is under cover, the Battery Master solution will significantly shorten the Starter batteries life because it is constantly 'watching' both batteries, checking for a change to happen. This monitoring process is constantly drawing power from both batteries, probably taking more than the Solar is harvesting when 'undcover'.

 

If you change to a duo MPPT Solar Charger wired through the EBL, removing the Battery Master, it will make the most of the poor light and put the power it does harvest exactly where it is needed, i.e. the Starter battery, without the drain of the battery Master.

 

You will probably more than double the power you harvest and keep both batteries better charged without them being run down by the power theft device.

If you don't have an overall three times improvement when 'undercover' I will be surprised.

 

 

If you want to see if our theory is correct and if you have a battery master, look near the EBL (often at the rear) for a Black Resin block with 3 wires, about 3.5" x 1.5" x 1".

 

 

 

 

 

[colin]

Yes it has the Stecca, don't think there is a battery master, can't see one, and also I now plug in a solar panel to cab when parked at home for over a week, this fully charges cab battery but leisure sits at 12.8v or there abouts. I should point out the cab battery was knackered when the van was left for a long period without driving and allowed to stay low voltage for too long, so that's purely down to my not looking after it

[aandncaravan]

Then I am puzzled how the Starter battery can charge back up on Solar alone if the Steca is going straight to the Habitation battery?

The EBL won't even be aware of the Solar to the battery so wouldn't be able to 'split' the charge to bring the Starter battery back up. Must be some other device somewhere that is doing that.

 

 

[BruceM]

aandncaravan - 2017-07-15 6:50 PM

 

But I am struggling to visualise a situation where you would have both Solar active and be plugged in to EHU?

 

 

In answer, we park the van on the driveway when at home.

 

When away for a week with no EHU, so just solar, it results in the batteries being partially discharged (note, we don’t TV, radio or internet when on hols so draw little power). Once home we EHU to get everything charged back up. So at home both Solar and EHU can be active.

 

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It’s comforting to know that the EBL 99 should cope with the two Vartas.

 

Re charging method – I’ve been reviewing the instruction manual for the EBL 99 D and the time based charging approach is usefully displayed there.

 

What I’m having trouble getting my mind around though is how the Schaudt charging module (LAS 1216) detects that charging is required before it activates the initial ‘boost-charge’ mode.

 

Will ‘boost-charge’ be activated as soon as we have EHU regardless of the battery charge state? If alternatively it first detects the battery charge state, can it do this reliably if the directly connected solar regulator is putting out 14.1V albeit possibly at a low current (let’s say 2amps).

 

 

 

 

[aandncaravan]

Different chargers work differently and the EBL 99 has had 2 completely different 16amp designs with 2 revisions plus an all new 18amp design (around 2005) which also underwent a major revision in the K version.

But yes the voltage will be relevant to deciding which of the three phases it will operate at.

At start-up it will usually skip the first one unless the battery is over discharged, going straight to the second phase (14.3v) when the timer also starts.

But be prepared for people to argue on this point, depending on which charger they actually have in their EBL they may see things differently, especially with the very first Wiesheuelektronik EBL 99 version.

 

However, even when it goes to the third phase, if the battery is low it will still take a draw from the mains charger, resulting in the battery still getting fully charged if both Solar and Mains are active within around 2 days. That is assuming the battery bank is carefully sized and the batteries not past it.

 

If you are concerned then remove the Fuse between the Solar Panel and the Solar Charger so that the mains charger can work unhindered.

 

 

 

 

 

 

[BruceM]

Vitronic 250W regulator now ordered – so that’s phase 1 of the solar revision commenced.

 

However, I’m struggling to locate a source for the Make N Lock connectors used on the EBL – I’m seeking a two pin plug.

 

I’m aware that they are Tyco-Amp MNLs but am struggling to determine the precise spec and for that matter a source.

 

Any pointers anyone?

 

[dipsticks]

I was considering buying one of the 'Wattmeters' (blue casing) mentioned earlier in this thread and noticed the statement:-

 

"There will be interference when measuring solar panel"

 

in the advertisement.

 

Not understanding the meaning of this I asked the seller who replied:-

 

"It means that if the Current pulse is instable which will burn down the item."

 

Sadly I still don't understand the answer and wonder if there is anyone that may be able to make this any clearer/easy to understand. Thanks in advance.

[BruceM]

BruceM - 2017-07-18 2:44 PM

 

However, I’m struggling to locate a source for the Make N Lock connectors used on the EBL – I’m seeking a two pin plug.

 

I’m aware that they are Tyco-Amp MNLs but am struggling to determine the precise spec and for that matter a source.

 

Any pointers anyone?

 

just to wrap up this loose end . .

 

I decided to take a punt on an ebay plug that looked the part and it turns out that it’s a perfect fit so if anyone else finds themselves in the same boat this is it http://www.ebay.co.uk/itm/350777-1-Te-Connectivity-Amp-Plug-Housing-Mate-N-Lok-2-Way-/362045766293?

 

 

 

[aandncaravan]

Glad you found the right plug. Sorry I didn't reply, been in Hospital, see more in this thread here : http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Conwy-motorhome-stopover/47508/

[aandncaravan]

Bruce, I made a statement above about Solar Panels losing output as they age - "We rarely see more than about 5 amps at 14.2v on a 100w Solar panel that is older than about 2 years, so will be surprised if your older panel can match that, even with a better Solar Charger?"

 

This is supported on a new thread about Solar Power from someone who has been using panels for some years, saying how one panel at 8 years of age is down to 60% efficiency, they quote -

" fitted solar panels 80 watt so are around eight years old although are at around 60% efficient now. ".

 

Effectively nearer a 50watt panel, rather than 80w?

 

See here for full details :

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Solar-panels/47548/

 

 

We stopped doing any Solar Work a few years ago because we were seeing Solar Panels which had either failed completely or well down on power. These were on panels which had the usual guarantee of 'minimum 80% power output at 20 years'.

 

So if you buy a new Panel, suggest you keep the receipts and Warranty as you are likely to need them well before 8 years are up, as shown above.

Several panels we saw were below 80% in less than 3 years.

 

To be fair, in almost all cases the Solar panel supplier provided a new Solar Panel/refund, so worth keeping the paper work, not just for yourself, but the next owner..

 

 

This is another reason for ensuring you have the tools that tell you exactly what your Solar solution is delivering and is at 100%, not slowly dropping.