Solar panels and leisure battery relation ship/ratio (1 Viewer)

[fizzle]

Hi

I have a 90ah leisure battery in my motor home and run a cool box at 5 amp/h and 4*5watt strip lights, if i would get say 5 hours of light, on a 150watt solar panel with a 20 amp controller, would this be enough to charge or keep the battery topped up? Is 150 watt enough and 20 amp controller powerful enough? If nothing was to run would it charge my battery even in winter in Scotland?

Thanks

 

[Robert Clark]

My back of a fag packet calculation is

5 amps is 60w
Your 150w solar panel will only deliver 150w at high noon, at the equator, so only in 100% ideal conditions.

In the U.K. in winter my guess would be maybe 20w.

Your 90ah battery can only deliver 50% of its total capacity, ie 45 amps, so will only power the fridge for 9 hours.

My advice therefore would be to increase your battery capacity and double your solar, and add a B2B charger if you don’t already have a split charge relay.

Hope this helps

 

[Richard n Ann]

^{_{Subscribers  do not see these advertisements}}

 

[DBK]

Welcome! To answer your last question first the solar panel should keep the battery charged in winter although you would want to monitor it if you have an alarm turned on which draws current, especially if snow fell or leaves landed on the roof. My brother lives in Fort William and has no problems over the winter although he does have 200W of panels.
We have a compressor coolbox and 190W of solar keeps it going but only when the sun is shining. In cloudy conditions in the autumn things would start to run down I fear.
With your setup it depends what sort of coolbox you have. The compressor types only run intermittently and are fairly frugal on power. The cheaper solid states types (Coleman etc) run continuously and you will struggle I think unless the sun is shining very strongly. You can save power by turning it off at night. We do this when necessary with ours.
If you are not sure what type you have try picking it up. If it is easy to pick up it isn't a compressor one - they are disc-slipping heavy.

 

[Pausim]

You might find this link to a solar angle calculator helpful http://solarelectricityhandbook.com/solar-angle-calculator.html
In mid winter in Aberdeen the sun only rises to 10 degrees above the horizon and I suspect you will get little or nothing from a horizontally mounted panel.

 

[Ivory55]

It’s a shame it’s not possible to have a small portable panel that in the winter you could angle at the right angle to boost a roof panel by just plugging in to the vans mppt so it does not upset the system.

^{_{Subscribers  do not see these advertisements}}

 

[Richard n Ann]

It’s a shame it’s not possible to have a small portable panel that in the winter you could angle at the right angle to boost a roof panel by just plugging in to the vans mppt so it does not upset the system.

I put ours on hinges

 

[fizzle]

My back of a fag packet calculation is

5 amps is 60w
Your 150w solar panel will only deliver 150w at high noon, at the equator, so only in 100% ideal conditions.

In the U.K. in winter my guess would be maybe 20w.

Your 90ah battery can only deliver 50% of its total capacity, ie 45 amps, so will only power the fridge for 9 hours.

My advice therefore would be to increase your battery capacity and double your solar, and add a B2B charger if you don’t already have a split charge relay.

Hope this helps

Hi just a follow up, is this per hour(20watt) or over the 5 hour period?
Thanks

 

[fizzle]

Welcome! To answer your last question first the solar panel should keep the battery charged in winter although you would want to monitor it if you have an alarm turned on which draws current, especially if snow fell or leaves landed on the roof. My brother lives in Fort William and has no problems over the winter although he does have 200W of panels.
We have a compressor coolbox and 190W of solar keeps it going but only when the sun is shining. In cloudy conditions in the autumn things would start to run down I fear.
With your setup it depends what sort of coolbox you have. The compressor types only run intermittently and are fairly frugal on power. The cheaper solid states types (Coleman etc) run continuously and you will struggle I think unless the sun is shining very strongly. You can save power by turning it off at night. We do this when necessary with ours.
If you are not sure what type you have try picking it up. If it is easy to pick up it isn't a compressor one - they are disc-slipping heavy.

Thanks

^{_{Subscribers  do not see these advertisements}}

 

[Pausim]

It’s a shame it’s not possible to have a small portable panel that in the winter you could angle at the right angle to boost a roof panel by just plugging in to the vans mppt so it does not upset the system.

I have two portable panels and a fixed mppt controller, which I plug into. The controller is accessible from an external locker, with plugs on short wires. I use splitters to add extra panels.

 

[PhilandMena]

Your getting some sound advice from members here. For my tuppence worth, I would advise, do it once and do it right. You can never have enough solar power, stick up as many equal solar panels as your controller can manage. If It was me, I would be thinking beyond your present needs and go for at least 400 W and more if I could, then just get the right controller and your good to go. Make sure your controller can charge the type of batteries (Lead Acid, AGM or Gel) you have fitted and can also charge your cab battery.

 

[Robert Clark]

Hi just a follow up, is this per hour(20watt) or over the 5 hour period?
Thanks

Per hour

^{_{Subscribers  do not see these advertisements}}

 

[bigtwin]

Hi just a follow up, is this per hour(20watt) or over the 5 hour period?
Thanks

It’s continuous.

Watts include the unit of time in that they represent 1 Joule/second.

Ian