Solar sizing for winter

[3crispies]

Getting fixed solar fitted locally as need to keep batteries topped up due to alarm/tracker drain. Have a battery master and will get this connected onto our existing victron 75/15 set up, instead of folding panels. Question is how much output will a 200w panel give compared to 100w this time of year. Never really needed solar when on our travels as we move every other day and have low power usage with Led lighting and gas powering cooking, heating plus fridge. Also need to be budget minded for this upgrade as if it wasnt for being in storage our original set up would work.
Tia

 

[Just smiffy]

200w panel should keep your battery daily topped up but I’d still take the van out for a good run at least every two weeks…

 

[Jabstatt]

I have 100w on the truck battery and it’s fine. Probably over the top.
460 on the lithiums but again, in storage, way more than sustaining.

Tony

 

[fishplug]

Question is how much output will a 200w panel give compared to 100w this time of year.

The facetious answer is "twice as much"

The sensible answer is that it depends where you are in the country.

There are various websites that will break down how much solar you're likely to get based on where you are and what time of the year.

e.g.

Solar Irradiance Calculator (with Map) - Footprint Hero

Calculate solar radiation for your location (city, address, or zip code) with our free solar irradiance calculator.

footprinthero.com

In the UK we generally don't get very much usable solar in the winter so I suspect Just smiffy isn't far off the money.

You'd need to have some idea of what the drain from the alarm/tracker looks like and then calculate what you'll be getting from the limited solar and also factor in days like we have here today where my panels are completely frosted up and will likely be getting close to zero.

Without data (including what capacity your batteries have) it's near on impossible to give you a meaningful answer of how long you can leave it without driving / charging.

 

[Lenny HB]

Our first van we only had a 80 watt panel and it copped but it really depends on the weather.
This year our 350 watts is only just about coping.

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[3crispies]

The facetious answer is "twice as much"

The sensible answer is that it depends where you are in the country.

There are various websites that will break down how much solar you're likely to get based on where you are and what time of the year.

e.g.

Solar Irradiance Calculator (with Map) - Footprint Hero

Calculate solar radiation for your location (city, address, or zip code) with our free solar irradiance calculator.

footprinthero.com

In the UK we generally don't get very much usable solar in the winter so I suspect Just smiffy isn't far off the money.

You'd need to have some idea of what the drain from the alarm/tracker looks like and then calculate what you'll be getting from the limited solar and also factor in days like we have here today where my panels are completely frosted up and will likely be getting close to zero.

Without data (including what capacity your batteries have) it's near on impossible to give you a meaningful answer of how long you can leave it without driving / charging.

thanks for that link, looks like Nov-Feb getting 0.4-1kw for the 200w panel. Our leisure battery is 115ah lead acid battery and fiat battery is fine for 4 weeks. Length of time parking up isnt an issue just looking for a good option so we dont drain battery too much and damage it.

 

[3crispies]

Our first van we only had a 80 watt panel and it copped but it really depends on the weather.
This year our 350 watts is only just about coping.

what sort of rewards are you getting from 350watts recently, especially with the frosty conditions. Went to MH yesterday and took it out, hadnt moved for 10 days and was properly iced solid everywhere, even the habitation lock was froze...

 

[Lenny HB]

Only about 50 to 100 watts on a bright sunny day. So 3.5 to 7ah total for a day.. Negligible when you have 485 ah of batteries.

 

[NPea]

On my little van I have 150 watts, I leave it for weeks and it always starts. Leisure and cab batts full but the only parisitic drain is charger LEDs

 

[Reallyretired]

200w on mine in storage and keeps the batteries up fine just running alarm tracker etc. As long as it doesn't snow, when of course we get FA.

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[Raul]

With 200w on the roof, I would say you will have a daily average of 7Ah per day, in the midd winter, south of UK.
Here is my break down:
My system on the van is 600w and looking at my data I have harvested 8400Wh in the past 30 days. An average of 280Wh per day at 13v gives 21.5Ah out of a 600W solar. At 200W that would be 1/3 of 21.5, about 7Ah.
Now, you need to find out the alarm and tracker 24hr consumption, and compare with this 7Ah.