Comparison of cheap vs expensive solar

[pet-els]

Talk to Terry about smaller and more panels as he put them on my 5'er. they should go around the curves of the roof.

PeterH

[T1 Terry]

We used blankets made from this stuff https://www.ebay.com.au/itm/10M-1-2M-AI ... 0005.m1851 double layer with a layer of bubble wrap in the middle. There are photos on the big bus build photo bucket site I think is linked to the globe thingo in my profile ... if that still exists of course. I'll add a link if I can't see it there.
The difference between the insulation that provided compared to the polystyrene is chalk and cheese. really notice the heat difference in the summer sun and cold in the winter freeze.
We had the condensation raining in every morning while we were fitting out the bus, but it didn't have a floor so it was the ground moisture condensing on the cold aluminium roof sheeting. Even after we fitted the floor it was still a problem, but once we fitted the airoshield insulation blankets the problem stopped.
To stop condensation or water soaking into plywood, paint the surfaces with https://specifier.com.au/products/const ... ion-paint/ and let it sink in, then any water just runs off. Makes that decorative covered wall panelling easy wipe clean as well, something that we discovered wasn't the case after we had clad the walls with the illusions paper covered ply from Bunnings. Now it appears it is no longer made ..... typical

[T1 Terry]

As far as the solar, we can make a frame to either fit the curve like the Avida has and then attach multiple 60w panels to that, or build a frame with legs each end to make a flat summer roof similar for the extra panels we fitted to Ian's 5'er (SemiD) or a combination of the 2 methods. The false roof on the tow vehicle works as well, the van can be in the shade and the tow vehicle plugged into the van system. The Hino has 1600w of solar fitted using the flat summer roof idea and works a treat in any weather, keeps the sun's heat to a minimum inside and even keeps the rain out of the roof hatch if we decide to leave it open to vent the cooking fumes

T1 Terry

[Grandad]

Hi Bruce, Some years ago for a totally different reason I had a need to really understand condensation in order to find a way to stop it on a job I had done.
This was long before Google so eventually I found the answer from one of the professors at Monash.

Here goes.
All air around us holds moisture. How much water it can hold depends (or is relative..... an important word to note) on the temperature. The higher the temperature, the more water it can hold.

If you watch the relative humidity through a day in summer here in Central Victoria where it is drier than a nuns whatsit, you will see the humidity reading drops as the temperature rises. That's because the AMOUNT of water in the air hasn't changed. But the relative capacity of the air has.

We measure this ability to hold water relative to the temperature as 'relative humidity' The max is of course 100%. And contrary to popular belief, 100% relative humidity does not equal rain. What does happen however is that the air will drop water on any surface that is cooler. It does so because the air immediately adjacent to the cooler surface drops in temperature ever so slightly. Because that air is now cooler, it can no longer suspend the water it is carrying and will drop it on the cooler surface. Condensation.

So, what is happening inside my caravan is that the air inside has heated up because of the sun shining on the van. Any moisture is absorbed into the air.
But at night, as the outside temperature drops, the air inside is still relatively warmer but as it touches the cooler roof, it drops its moisture

To combat this I have several choices.

Remove the source of moisture.
Not possible as it is absorbing it from everywhere. There is no obvious source such as a full sink etc. This is where your reverse cycle AC comes in. In Canada where I grew up and humidity was ridiculously high we had dehumidifiers.

Make the inside and outside temperatures the same.
Open windows etc. I'm leaving my windows open now for this reason.

Insulate the cold surfaces so there is not the differential in temperature to the air immediately adjacent to it.
This is where the 25mm of polystyrene comes in. Or the stuff that Terry has mentioned.

There is no condensation between the outer skin and the polystyrene because there is no air there.

Cheers
Jim

[Grandad]

Thanks Terry. Most of the roof is already finished with the polystyrene and finished 4mm ply so too late to try the blanket. Its only a relatively small section in the middle that is causing the problem.

All the cabinetry inside is stained and polished timber so I'm dubious about using the paint product you listed. At any rate, I'm sure the 3 coats of poly I've put on the timber will seal it pretty well. I'll convince myself of that anyway because its too late to change.

I have however purchased a tin of a heat reflective white paint for the outside roof. It was mentioned in a thread somewhere on either the nomads or that other forum and everybody raved about it. Gotta paint the roof anyway so I'll use that.

Yes, some sort of frame to hold the solar panels was what I was thinking of. I'm fairly confident of being able to fabricate what I need. I have to do as much as possible myself as I'm quite concerned about what your total bill will be once I'm ready for my trip to Mannum. It's gunna hurt. I'm ready for that. But the more I can do beforehand the better.

I just need to spend some time seeing what sizes are available and how they will fit. I already have a germ of an idea on how to frame them.

A piece of flat steel bent to follow the curve that is bolted through the roof. I wasn't happy with pop rivets or sheet metal screws into the aluminium/plywood roof. So I'm currently thinking a domed head inside and a nut on the outside. I can live with that.
From there of course, I can weld uprights to something to hold the panel.

I am leaning more and more to the pack rack idea. Ideally, there should be enough solar on the van itself to make the system relatively reliable on its own in good weather. But the ones on the ute are there to help out on those overcast days etc. It just means, if its a dull day, maybe I won't be able to drive off somewhere for the day. Or, don't use the microwave.

Or...….. Make the array removable? Nah. Would be far too heavy on my own.

Maybe this might be a good time to get some kind of guidance or opinion on exactly what I will need in way of cells and therefore solar etc.

Originally, I was thinking all electric. Zero gas and therefore zero cost for energy. It seems that 400AH of lithium powers just about anything you want including AC etc. So, that's what I was planning on. But, as time goes on and my circumstance changes and the possible end use of the van changes I'm mellowing.

I now have a two burner LPG cooker I bought on eBay. The fridge is a small 240V AC bar fridge. I'll have to pull it out to see exactly what wattage it is but hopefully you will have some rough idea. I still have the inverter cooker but I can leave that for when I'm plugged in.

I purchased an inverter microwave. It will be used for an absolute maximum of 10 minutes a day.

I'd like to be able to have an electric blanket and I plan on a diesel heater. No water pump. All lights LED. A couple of charge point for phone and iPad.

Plus a laptop, small TV and Fetch box.

I'm thinking maybe 200AH might be enough with say 300 watts of solar on the van plus whatever I can fit on the Ute. That's an off the top of my head calculation (guess) on my part.

What are your thoughts at this stage?

Jim

[T1 Terry]

Aluminium racking for the van roof or tow vehicle roof, steel is too heavy. We have a device here that can form a curve along a length of 20mm square tubing and that welds up into a very strong frame that can hold quite a lot of solar. You will need plenty of solar to cover the poor solar days so you have enough to keep the fridge running.
To a degree, the more solar means the less battery capacity, battery capacity is the number of days with poor solar you can handle, the more solar means you have better solar harvest on poor solar days. The over night use is the part where the battery capacity minimum comes into play, you need enough to go at least 1 full 24hr period with no charging at all.
If you have plenty of solar you can run an extension cord out to the bloke beside you that wants to run a generator to power his battery charger or small tv so you can both enjoy the peace and quite.

T1 Terry

[pet-els]

Terry,
I see grandad is in Bendigo. I will be at the CMCA Rally in October, if he likes he could come and see mine. 22 x 60w panels.

PeterH

[Grandad]

Hi Peter,
What's CMCA please?

22 panels? I assume you have heaps pf roof space to work with. My van's body is 10' 6" long with a curved roof. Can't honestly see 22 panels fitting up there.

Cheers
Jim

[BruceS]

https://members.cmca.net.au/news/7aed6c751

[Grandad]

Thanks Bruce. So, who all is going from here? Do you know?

Jim