Am I Expecting Too Much From My Solar Panels

[Alesupper]

Hi

I have just had solar panels fitted to our campervan so I have no experience with them and what to expect from them. After one night away in the van the battery was down to about 12.2v which I felt was fair enough. The following day was overcast and grey with no sunshine and I parked the van up for 8 hours whilst I did a long bike ride. When I returned the battery was at 12.7v but I was hoping that it would be fully charged (i.e. 13.5v). Should 2x120w solar panels be able to fully charge a 100Ah leisure battery in these conditions in 8 hours or am I expecting too much?

My other concern is that our leisure battery might be past its best. It is 3 years old. By the second night it was too low for our Avtex TV to operate more than 20 minutes and we hadn't used much electricity at all. Would a duff battery recharge slower than a battery in good condition?

Apologies for the numpty questions.

TIA

 

[Vic]

What type of controller has the system got?

 

[Flairy]

My battery’s are nearly 20years old I have 4 100 amp 3 100watt solar panels perhaps your battery isn’t good I would have it checked , then by the best battery you can justify, if your solar panels and regulator are questionable You can have them checked for output . I had mine checked by Chase RV , Garry is very good.. hope this helps.

 

[Tombola]

Are the batteries lead acid? if so you only have 50% useable, then you can work out what you use . Was your fridge on etc...fridges consume lots and would swallow that 50a in very short time, even 3-4 hours..
lithium would get you 80-90%

You really need an mppt charge controller to get the most from your panels.
240 solar could in theory put that back in with a decent mppt if sunny, they would poss generate 7 a each (14 per hour) when good sun .

there are lots of variables but try and think what power you use in a day.
But if your batteries are kaput (ish) its a running battle.

 

[Phill D]

12.2v is flat..... 12.7 after a short rest is fully charged.

How many hours of TV were you using...

It does sound as if the battery needs testing to establish its condition

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[Stealaway]

I think you need new batteries.
Now you have all that solar you should a new pair of larger ones

 

[Alesupper]

What type of controller has the system got?

Both the solar panels are PV Logic. The controller is just a standard one for now as I am waiting for them to supply a MPPT controller, which should improve things hopefully.

 

[tonyidle]

Hi

I have just had solar panels fitted to our campervan so I have no experience with them and what to expect from them. After one night away in the van the battery was down to about 12.2v which I felt was fair enough. The following day was overcast and grey with no sunshine and I parked the van up for 8 hours whilst I did a long bike ride. When I returned the battery was at 12.7v but I was hoping that it would be fully charged (i.e. 13.5v). Should 2x120w solar panels be able to fully charge a 100Ah leisure battery in these conditions in 8 hours or am I expecting too much?

My other concern is that our leisure battery might be past its best. It is 3 years old. By the second night it was too low for our Avtex TV to operate more than 20 minutes and we hadn't used much electricity at all. Would a duff battery recharge slower than a battery in good condition?

Apologies for the numpty questions.

TIA

Overcast and grey would put very little back in the battery. More important is the size and condition of the battery to allow you to get through a couple of grey days.

 

[Off da Grid]

If you had full sun maybe by 4 o’clock with an mppt controller if that flat no.
If your Avatar pic is your van we have similar and our usage is minimal.
Led lights, occasionally water pump usage, fridge on gas but still uses power.
Some charging of iPads and phones maybe tv, but no much this time of year.
We have 255watt panel and Votronic 350duo mppt controller.
Usually my 110amp leasure and top up of starter battery would be fully charged by 10am in the summer, definitely by lunchtime this time of year if full sun.
On a light cloudy day maybe by tea time.
I can tilt my panel but usually don’t need to till end of September.

 

[Alesupper]

If you had full sun maybe by 4 o’clock with an mppt controller if that flat no.
If your Avatar pic is your van we have similar and our usage is minimal.
Led lights, occasionally water pump usage, fridge on gas but still uses power.
Some charging of iPads and phones maybe tv, but no much this time of year.
We have 255watt panel and Votronic 350duo mppt controller.
Usually my 110amp leasure and top up of starter battery would be fully charged by 10am in the summer, definitely by lunchtime this time of year if full sun.
On a light cloudy day maybe by tea time.
I can tilt my panel but usually don’t need to till end of September.

Thank you, that is useful info and yes, the van in the avatar is our van.

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[Off da Grid]

I have seen 13 amps from our controller the panel is rated at 8 something so mppt will make a big difference, especially on cloudy days.

 

[robert groves]

Hi

I have just had solar panels fitted to our campervan so I have no experience with them and what to expect from them. After one night away in the van the battery was down to about 12.2v which I felt was fair enough. The following day was overcast and grey with no sunshine and I parked the van up for 8 hours whilst I did a long bike ride. When I returned the battery was at 12.7v but I was hoping that it would be fully charged (i.e. 13.5v). Should 2x120w solar panels be able to fully charge a 100Ah leisure battery in these conditions in 8 hours or am I expecting too much?

My other concern is that our leisure battery might be past its best. It is 3 years old. By the second night it was too low for our Avtex TV to operate more than 20 minutes and we hadn't used much electricity at all. Would a duff battery recharge slower than a battery in good condition?

Apologies for the numpty questions.

TIA

I think the answer is lays with your statement," overcast and grey with no sunshine ",....I have 3 x 100a batteries, and 2 x 150w @32v Panels , and unless there is direct sunlight, i only get about 2 amp. using 'Ohms law,...12v x 2 amp = 24w !...so not enough even for a small TV .
I have 12 Large panels on the roof of my house, and on cloudy days, won't even charge enough for the fridge/freezer (120w)
Another thing to check, is that there are No Leaves or other debris/shadow on the panels, as we have found that even a couple of leaves can dramitically reduce their output !
The Solar system on our house cost £12k, and saves us about £500 per year, so,..24 years payback time (unless the price per unit vastly increases)
I have come to the conclusion that the only people who make money from Solar panels are the Bank (capital outlay loan) the Panel installation company, and the Electric company (French) who give us a massive 4p per unit for the excess units we sell to them (then they charge 18p per unit to sell it back to us in the night time)

 

[Alesupper]

Thanks Robert, that is very useful information. I guess I was expecting too much from my panels.

 

[robert groves]

Thanks Robert, that is very useful information. I guess I was expecting too much from my panels.

I usualy rely on running the engine for 30 mins in the daytime (as long as there are no other MH's nearby)

 

[Raul]

I think you discharged a fair bit and the solar did not had the weather to put back all of it.
Have a look at this link, you can calculate the solar harvest based on location, angle and panel mounted on roof or free standing if is on the ground. Enter the relevant details on the right, and divide the result of wh by 12v in your case.

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission

Photovoltaic Geographical Information System (PVGIS)

re.jrc.ec.europa.eu