SOLAR PANELS FOR MY VAN

Fee Bee · Newbie

SOLAR PANELS FOR MY VAN

blaze · Guru

there is a sub section just above your post called solar, have a good read through there
cheers
blaze

Whenarewethere · Guru

As said above.

But a back of the envelope calculation. You have 12000 watts divided by 24 volts (12 volts is no appropriate on such a large requirement) = 500AH (24 volts)

If going lead acid you need 1000AH minimum running down to 50%.

To recharge 12kWh in 4 hours you need 3000 watts of solar. Since panels are on the roof 70% efficiency at best. So 4000 watts or more.

Then allow losses in the system, running & charging.

Not to forget inclement weather so you will need more batteries & more solar.

The weight will be 400kg, which can be reduced with lithium but double check price!

Whenarewethere · Guru

Your killer is heating. Look at a 2.5kW reverse cycle split system air conditioner Daikin or similar. They are +500% efficient.

kgarnett · Senior Member

Do the math.

Fridge 60W x 24h = 1440Wh + Hob 2000W x 1h = 2000Wh +
Mini Oven 1150W x 0.5h = 575Wh + Heater 2000W x 4h = 8000Wh +
Laptop 30W x2h = 60Wh

Giving a total of 12,075 Wh per day

Assuming 24V supply then 12075Wh/24V = 503Ah per day solar input required (minimum).

Assume for convenience 6h per day of solar input, then you would need 503/6 = ~84A continuous for 6h /day. Ie a average 2016W over 6 hours (84A x 24V)

If you assume an ideal 200W/m2 output from solar panels, then you would need 2016/200 = ~ 10m2 of solar panel to power your stated requirements.

Summary you would need an absolute minimum of 2000W of solar panels which would require at least 10m2 of panels under ideal conditions.

Perhaps you should rethink your requirements particularly the 8000Wh of heater.

Ken

Happy to be corrected of receive criticism.!!!

-- Edited by kgarnett on Tuesday 12th of May 2020 08:23:45 PM

Mike Harding · Guru

Throw away all notions of the electric hob, oven and heater.

For cooking use a gas stove and either a gas oven or a Coleman camping oven which sits on top of a gas ring.

For heating, a diesel heater is most effective and very cheap to run. If you cannot install it yourself it will be expensive at around $1500 to $2000 but worth it.

For the fridge I advise an absorption (three way) type which will also run from gas.

That leaves the laptop; a 120W panel should cover that easily, I suggest a folding portable panel with built-in controller and 60Ah battery.

Tell us what type of travelling/camping you intend to do and we may be able to advise more specifically.

Jaahn · Guru

Fee Bee wrote:
Hi :).
I have recently purchased a van and would like to buy a/some solar panels to attach the the roof rack to power my electrical appliances. I have listed all of the appliances I would like to use below. I will not be using all of the items 24hrs a day and not all at the same time, I have therefore also listed the amount of time per day I think I will use each appliance.
Electric Hob 2000W 1hr per day, Electric mini oven 1150W 30min per day, Electric heater 2000W 4hrs per day. Too much power needed to run off solar and batteries normally.
Laptop 30W 2hrs per day, Fridge 60W 24hrs per day
Can anyone help me to figure out everything I would need to run these appliances. For example 300W solar panel, inverter, 24V battery?
I do have the option to purchase a gas hob rather than using the electric hob if this will allow me to spend less money on solar panels and batteries.
Thanks for taking a look for me any advise is much appreciated!

___________________________________________________________________________________________-

Hi Fee Bee smile

Lots of answers given that are good advice so I will just summarise.

You can do anything you want on your list but the cost is the first problem. Then you may not have enough area on the van roof to fit so much solar, and the battery size required is excessive, so be reasonable about your needs and look at what is commonly used in vans.

Vans usually have gas bottles to use for cooking and hot water and can be used for heating too. It is an easy way to get the energy required for these high usages. They do not cost too much to fill every now and again, just like your tug fuel tank. You can use gas for a 3way fridge too.

For space heating use gas or you can get a diesel heater which uses very little fuel over nights. Cheaper than gas. Plenty of discussion here on fitting them too. Also diesel water heaters.

So what does that leave to run off solar and batteries. Well inside lights should be on your list. Get LED 12V globes for efficiency. Laptops/phones need 12V chargers and charge them during the day when the sun shines. A 12V compressor fridge is efficient and an OK user of power. Perhaps a 12V radio or TV too. This electricity usage is reasonable and you could get by with say about 200+Ahr batteries and 300W solar panels (more is better) and expect this system to work OK.

If you really do want to run more solar and batteries then read the threads in the Solar Power The place to discuss all things solar, sub forum above and get some ideas there and ask again. IMHO. If you can do the work OK but if you have to have it all installed then budget for a lot more.

Jaahn

-- Edited by Jaahn on Wednesday 13th of May 2020 12:58:03 PM

Whenarewethere · Guru

I will add, don't go cheap to save money. It will cost more in the long run. Buy quality products & do it once.

Also get the guage of the wiring right. This is a real pain in the neck doing it once, not something you want to do a second time because one has been a tight ar_e. Wire resistance is the total length of + & - !

Design the layout so you have some head room in the solar controller, it will run more efficiently, especially in hot weather.

My personal preference would be 2 panels in series then in parallel, so 4 panels or 6 panels, using an MPPT controller. (I don't want to start a 3rd world war on this issue!)

Fee Bee · Newbie

thank you so much that really has helped! I have now re looked at what I need and have got it done to 3140WH. Therefore I will look to get a 1.5m 350W solar panel. I only have a small Kia Pregio and am looking to do a 3 month trip...I think I was very ambitious with what I could do with a solar panel.

Whenarewethere · Guru

We travel around Australia for about 3 months at a time. We sleep in the car, chucking everything in the front overnight, including fridge.

The best thing you can do is add acoustic insulation for the thermal benifits. A lot easier to do in a van than a car. Cut windscreen sunshades to size to fit every window. You don't need a heater.

https://thegreynomads.activeboard.com/t65443581/car-acoustic-insulation/

A compressor fridge is the go, & keep it small. Depending on your style of travel, if you move every few days you won't even need solar panels. We didn't use our solar once last trip with the longest stay of 3 days as we have a DC-DC charger to charge up our 4 x 26ah batteries.

We use metho for cooking. Carry 65 litres water & are at our 500kg payload capacity.

P.S. Get TPMS, tyre repair kit & quality compressor.

Whenarewethere · Guru

Have a look at this thread at my post with spreadsheet weight data. It's frightening how quickly weight adds up!

https://thegreynomads.activeboard.com/t65110614/towing-weights-again/

Whenarewethere · Guru

Some real data on fridge efficiency. A 40 - 60 litre fridge uses a compressor just a whisker larger.

https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/

Jaahn · Guru

Fee Bee wrote:
thank you so much that really has helped! I have now re looked at what I need and have got it done to 3140WH. Therefore I will look to get a 1.5m 350W solar panel. I only have a small Kia Pregio and am looking to do a 3 month trip...I think I was very ambitious with what I could do with a solar panel.

Hi Fee Bee smile

We are glad to be helpful on here biggrin You might have been ambitious but why not start out like that ! We all started somewhere to get here. hmm

Just to clarify what has been said by Whenarewethere you can also charge your battery with the car alternator. It is the best charger you have and works while the engine is running. If you do a driving holiday where you drive most days you may not even need solar panels(as he said). So make sure you fit either a VSR(voltage sensing relay) or a DC-DC charger. I think your Preggio will work with the VSR but newer fancy vehicles need the DC-DC charger. I use a VSR in my Sprinter van and if the sun is 'away for the day' you can run the engine for a bit. You can ask a question about this or PM me.

I would suggest, as I have in other threads, that instead of one big 350W panel you fit two or three smaller ones. There are good reasons. If you want help with the selection of them ask again. You must be careful you get suitable panels or you will be disappointed. I did not see a recent post about this as very helpful ?? Also the solar regulator/controller, there are lots of cheap ones but some are poor and some just do not do the job they say. disbelief It is important that you have a meter you can see easily to tell you what the state of the battery is. Then you can be happy they are working OK. Some reg/controllers may have one fitted or can have a remote one, or even a smart phone might read it.

I would also agree about fitting insulation in any van. A big metal 'box' is very cold inside at night.

Cheers Jaahn