Solar panel advice

[sotal]

I have read lots of the posts on here regarding solar panels and the issues around quality and the general advice on where to buy from. I've spent time on a few occasions researching but never got to the point of actually ordering anything. I would like to order this year before we go away.

However my requirements are a little different to most peoples. We use a long roof box and a new dawn conversions roof rack. This has given us the perfect solution to storage. This however only leaves part of the roof accessible for a solar panel.

I'm thinking of using a semi flexible panel - for two reasons. 1 - they seem to be lighter. 2. The roof rack does bend slightly in the middle when the box is full.

I'm thinking of using two aluminium box sections to bolt the panel to, then bolt the aluminium to the roof rack.

I'm thinking of using an MPPT controller.

I need to check sizes but I'm hoping something like this will work:

ebay link

Perhaps with something like this:

ebay link

I've just ordered a new Yuasa leisure battery to replace my failing one.


So questions!...

is there anything wrong with either of the things I've posted above?
does my method of installation sound ok?
would I need anything else as well?

[Katka]

There's good info on this thread http://igmaynard.co.uk/bongo/forum/view ... ilit=solar

[sotal]

Yes, as I say I've read the posts on the forum.

I think my method of installation should adhere to the advice - bolted to alloy, then bolted to the roof rack. I've chosen a MPPT controller based on the advice too.

The offerings from the company suggested don't suit my needs.

My biggest concerns are how to know if the panels are any good or not.

[Munch]

Are solar panels worth it in the uk where it's rarely sunny?

[g8dhe]

Yes, solar cells these days are quite happy working with indirect cloudy light as well especially when using an MPPT controller see here for more info http://igmaynard.co.uk/bongo/forum/view ... 13#p679313

[BenjiBongo]

I fitted one of the semi flexible ones (100w) with marine sealant/adhesive. It's still doing a grand job. Was quite straight forward.

Pic here http://imgur.com/SuAm24H

[Bongolia]

I fitted one of the semi flexible ones (100w) with marine sealant/adhesive. It's still doing a grand job. Was quite straight forward.

Pic here http://imgur.com/SuAm24H

Nice, who did you get it from and how much?
I was going to replace mine with something like that but couldn't find one that didn't overlap the light.

[timhowes]

FWIW my experience with similar kit has been good over the past year.

100W semiflexi panel with Sunpower cells (whatever this actually means!) from Renytek.co.uk
10A MPPT controller (Tracer 1215BN) from Bimble Solar

Paid a little more for each component compared with than the ones you linked to, but nearly bought that same controller. Think I went for mine because it was a bit lower profile (installed on a mount I made under the glove box, on the bulkhead - out of sight and dissipates heat to passenger's knees!).

Installed myself with a tube of goo and a bit of head-scratching about cable routing, and it has since performed flawlessly. I monitor the input/output with the plug-in display unit I bought in addition for my controller.

Your roofbox mount sounds good. Ideally leave air gap underneath to keep the cells cool and efficient.

Good luck!

[sotal]

OK - A little closer now. I should be fitting the roof rack and roof box back on (roof rack removed to strip down and repaint). I will then be able to work out the exact size etc. that I have.

A couple more questions that have dawned on me...

Whilst camping the primary goal will be to keep the LB topped up. However during the normal week it would be nice to change this to the SB to ensure optimum stating etc. The LB isn't used much during a normal working week and the engine charges that enough. Is it possible to do this? Or as a minimum does the split charge work in reverse - will it also charge the SB when the LB is above a certain voltage?

When choosing a location for the MPPT unit. Is it better to be closer to the panels (Perhaps top cupboard above side conversion) or closer to the battery (perhaps footwell or in the dash somewhere?)

[g8dhe]

You can get controllers with dual outputs to charge two batteries, which might e your better choice.
However do be aware that if you do have a standing load on the LB then the constant discharge/recharging means that you are using up the 200-300 charge cycles that most LB are rated for.

[mikeonb4c]

You can get controllers with dual outputs to charge two batteries, which might e your better choice.
However do be aware that if you do have a standing load on the LB then the constant discharge/recharging means that you are using up the 200-300 charge cycles that most LB are rated for.

Indeed Geoff. From the chat we had on another thread it is perhaps better not to be putting any (lead acid) battery through charging cycles except where necessary?

Out of interest, what hapoens to a solar panel when it is generating electricity for which there is no demand - can this have any detrimental effect on the panel or controller?

[sotal]

You can get controllers with dual outputs to charge two batteries, which might e your better choice.
However do be aware that if you do have a standing load on the LB then the constant discharge/recharging means that you are using up the 200-300 charge cycles that most LB are rated for.

Are we not getting that constant cycle anyway through the daily use of the Bongo?

What would be the solution? Isolate the LB until going away?

[mikeonb4c]

You can get controllers with dual outputs to charge two batteries, which might e your better choice.
However do be aware that if you do have a standing load on the LB then the constant discharge/recharging means that you are using up the 200-300 charge cycles that most LB are rated for.

Are we not getting that constant cycle anyway through the daily use of the Bongo?

What would be the solution? Isolate the LB until going away?

Geoffs the guy to answer this but its a good point. And my LB cant ever really be isolated as several things have been rerouted to run off it. If i fit solar then, like you are thinking of doing, i might wish it to keep both batteries topped up at all times.

[sotal]

The only way I can think to effectively do it would be to have a switch the moves everything over from the SB to LB when you go camping. I would imagine you would then flick it over as you set off to give the LB a good charge. Then leave it set for the duration of the stay during which time it would constantly charge/discharge. Leave it set that way for the journey home to ensure it was charged then flick it back over to the SB so the LB remains dormant until the next trip.

That's without considering the Solar Panel. Which again you may want to switch between the two so it charges the SB daily and only touches the LB when away?

But then would that shorten the life of the SB?

[the1andonly]

OK - A little closer now. I should be fitting the roof rack and roof box back on (roof rack removed to strip down and repaint). I will then be able to work out the exact size etc. that I have.

A couple more questions that have dawned on me...

Whilst camping the primary goal will be to keep the LB topped up. However during the normal week it would be nice to change this to the SB to ensure optimum stating etc. The LB isn't used much during a normal working week and the engine charges that enough. Is it possible to do this? Or as a minimum does the split charge work in reverse - will it also charge the SB when the LB is above a certain voltage?

When choosing a location for the MPPT unit. Is it better to be closer to the panels (Perhaps top cupboard above side conversion) or closer to the battery (perhaps footwell or in the dash somewhere?)

When the car is being used the primary use of solar charger should be to charge the LB. (camping season)
to reduce residual drain on LB do not swap functions that have a residual drain, ie fuse 1. if required for radio run a separate fused feed from LB. Leave interior lights on SB (cabin light run 1 of LB 1 off SB) and add extra LB lights in rear. Same with 12V sockets leave front on SB add LB in rear. Why? If you camping in middle of nowhere and LB dies on a bank holiday you still have light and power. Fuse 1 also powers ECU no LB no start, just need to swap back and all ok (whos going to remember that in heat of moment).
Winter (car not being used) primary use of solar charger could be to charge the SB. swap feeds over. If done with a switch OK, if done manually be very careful to reconnect correctly or you may end up with no charging of LB and Nakering the LB. IF done correctly the solar charges the SB and a Voltage controlled split charger will maintain the LB in winter.
If solar charging of SB is required either the battery or alternator system is US.

Position of charge controller: mine is under bonnet behind the SB. The diameter is huge, the loss should be less than if at the back, but in saying that you should be using 30A cable( even 2 in parallel) . If the difference in loss is significant to you , you are either using wrong cable or too small a panel for your needs. So put it where you feel is most appropriate to you, or easiest to run.