Campervan 24V 280AH LiFePO4 3 x 370W solar panels

[beton]

Hello.

First post. I have sat on the side for a few weeks.

The audacity of covid.

I was never going to do the grey nomad thing. Hauling a caravan around the countryside will not cut it with me. Then I saw Canada and saw that you could get a campervan and drive and park and see. Plan A was to go to Canada and get a Promaster LWB EXT hi roof and do a high quality build with a high spec. Then cruise thru Canada and the US over 2 years and ship the van to Australia. I am comfortable driving left hand in Aus. Not so the other way. Then do the lap of honour around Australia and a couple of eights. Then use the van for getaways. In due course give the van to the kids.

Covid changes that. Now I am looking at getting a good used van in Australia, doing a high quality build with functional spec to a budget. Do the Australia and New Zealand touring and sell. The build would have to be cost effective as the resale value would be based on the vehicle. The buyers expect the fitout for nothing. We would have to target the $50,000 range. If it is safe to travel then I would repeat the build in mirror image in Canada and tour there including the States, selling after two years. Again, the build would be aimed at the resale value.

There is not much cost between a high quality build and a bad build. Just care and attention. However there is a lot of money between a functional spec and high spec. A lot of that money (most) is in the electrical. For that area I need advice so that I clearly see where I am going. I have been a builder all my life, I have a EE that I play golf with, a BIL who is a process engineer and 4 nephews that are electricians. I still have to point the direction for them to help.

I am looking at all electric. Thus there will be induction cooking and some common appliances. I am trying to avoid the microwave or oven but her indoors may have something to say about that. The fridge has to be largish but 12v. With the exception of the A/C the 240v and 12v loads are standard and well covered with the battery.

In Australia there is no getting away from the heat. Nor will there be getting away from the humidity especially in Northern Territory and Queensland. I am hoping that the heat can be managed with only running the A/C 6-8 hours per day. The A/C will be a 8,000 BTU window A/C with soft start, mounted high inside and vented. This will be the heaviest demand for maybe 4 months of the year. The upside is that when the A/C is needed, the sun will also be shining.

I am not interested in boondocking so we will be driving 2-4 hours most days. Do some sightseeing, fishing or golfing. Find an over night parking spot, rinse and repeat. As required, we will stop in a caravan park for a recharge, water and laundry. I apologise for the ramble, I think it will help.

I am proposing 3 x 370 w panels on the roof. That is the practical roof real estate. I am proposing a 24v 280AH battery made from 8 280AH LiFePO4 cells. This will then have a 24v to 12v convertor for the 12v loads and a 2000 W or 3000 W 24v t0 240v inverter. This may also have a charger.

I do not propose at this stage to consider running off the chassis alternator.

Should there be a shortfall in solar input, I can add another panel at a higher level over the exhaust fan (or even relocate the fan). I can also set up to deploy 2 panels from under the original three panels. Thus we can have 3,4,5 or 6 panels if required. If there is a shortfall in battery capacity, we can add another 24v 280AH battery. (increase to 48V ??)
The extra 2 panels deployed from under the main panels seem to be practicable as an awning on the side of the van. Thus we are better to consider 3 panels then 5 panels and 6 panels if required.

The battery will be the 280AH cells as detailed on this forum. The solar panels will be Solaria PowerXT-370R-PD monocrystalline silicon panels. 48.3v @9.2A. Max 54.3v @15A. https://static1.squarespace.com/sta...00115/Datasheet_PowerXT_Resi-370PD_Rev_04.pdf

What I need is the simplest, safest, cost effective and reliable means to get the solar power into the battery and then out into the house 12v and 240v circuits.

Could this PIP 3024GK do the job? https://www.mppsolar.com/v3/pip-gk-series/

I will take all advice.

Thanks Beton

 

[beton]

Solar panel layout. By using the two slide out panels on actuators, I get an extra 2 panels and an awning. I will need some advice on the best way to connect to the SCC.

 

[HRTKD]

I am not interested in boondocking so we will be driving 2-4 hours most days. Do some sightseeing, fishing or golfing. Find an over night parking spot, rinse and repeat. As required, we will stop in a caravan park for a recharge, water and laundry.

That sounds like boondocking to me. I don't understand why you say you're not interested in boondocking.

The air conditioning is going to be the biggest energy hog in terms of daily consumption. The induction stove would come in a close second. I would start with the air conditioner's watt hour consumption and design the rest of the system to support that. I haven't run your numbers but I'm not convinced that 3 x 370w panels is going to be enough. Your additional panels, in whatever deployment you come up with, are going to be needed.

 

[beton]

That sounds like boondocking to me. I don't understand why you say you're not interested in boondocking.

The air conditioning is going to be the biggest energy hog in terms of daily consumption. The induction stove would come in a close second. I would start with the air conditioner's watt hour consumption and design the rest of the system to support that. I haven't run your numbers but I'm not convinced that 3 x 370w panels is going to be enough. Your additional panels, in whatever deployment you come up with, are going to be needed.

Thanks HRTKD. That is a conclusion that I came to and added the extra panels. If we park up at noon on a hot day, we would need to run the A/C and top up the batteries. As the sun goes down less power will be available for the batteries. Eventually there will be a draw on the batteries and we may have 5-6 hours available to run the A/C if required. In most places the ambient temperature drops rapidly once the sun goes down.

I do have some concern where there is high humidity. However these places have survived and continued to survive with fans. I will add another battery should there be a proven need and make provision to do so. At present I do not see the need or the cost.

I will do a detailed power audit as I progress. My first task is to work through that it is doable and how to do it.

I see boondocking as parking up in one spot for an extended time. I prefer to go and see and then leave.

 

[HRTKD]

"Boondocking" to me is camping without utilities, usually in dispersed camping situations. The time spent there isn't something I considered in the term.

I looked at putting in an induction cooktop. I probably have the battery capacity (560 Ah) to support that. However, my voltage (12v) doesn't lend itself to the amperage that an induction cooktop can pull. I would need at least a very high quality 2000 watt inverter, probably 3000 watt. My puny 1000 watt inverter would never work.

 

[beton]

"Boondocking" to me is camping without utilities, usually in dispersed camping situations. The time spent there isn't something I considered in the term.

I looked at putting in an induction cooktop. I probably have the battery capacity (560 Ah) to support that. However, my voltage (12v) doesn't lend itself to the amperage that an induction cooktop can pull. I would need at least a very high quality 2000 watt inverter, probably 3000 watt. My puny 1000 watt inverter would never work.

I worked on self lock storage facilities going back into the 1970s. It was basically the birth of them in Western Australia. The feedback which still applies today was that people retire and decide to do the "lap of honour" IE tour around Australia. They buy a caravan and upgrade to a bigger vehicle to pull it. They rent a big storage unit and give themselves 12 months. They move their furniture out of the home and rent it out. After 12 months they come back and sell half their furniture and reduce the size of the storage unit. After another 12 months they return and cull more stuff until they only have quarter the storage space.

An overwhelming response was that with the pension, what little savings and the rent from the house, they could have a good retirement on the road. That was incumbent on finding places that they could park up for weeks or months at a time without camping fees. In a numerous amount of cases they could not move until they got their next pension check in order to pay for fuel.

In a majority of cases people were trapped into staying on the road because they could not survive just on the pension if they returned. Most started out with an expected 12 months. On average they were on the road for 4 to 6 years, only returning because of health of one or both partners.

Boondocking to me is these extended stays in these free camping spots.

For me I see the necessity of the A/C. Therefore I must have the capacity and equipment to run the A/C. The amount of time that the A/C will actually be used is small. I worked most my life in the the heat. In the bush, in the north west, in the desert, in Perth in the summer heat. Any touring will be based on avoiding the heat. Most meals can be done in a short time frame. Where there is a conflict for power, there are public BBQs, portable BBQs for external use, campfires and common kitchens in caravan parks. Otherwise there is more than enough power available to have a gas free van.

 

[beton]

This is the point where I need the expertise and experience of the forum members. Any help is appreciated. If my thinking is off the mark we can always change it.

My objective is cool my proposed campervan. I am aiming at 5-6 hours of cooling when required. I will take what we can get. I will also have an induction cooktop and the usual power requirements.

My second objective is to keep within a budget circa $5,000. The reason for this is that my principal usage is 2 years fulltime and thereafter the vehicle will be sold, given to the family or just short term use. Any buyer is not going to pay for a high spec build.

At present I have put having power from the alternator off the table. Although we plan to drive most days, the charge rate is small without going to additional equipment. A generator is not an option and the option of shore power is there, I do not want to depend on it.

Thus the decision to date is to totally solar. I have decided on using Solaria PowerXT- 370R-PD panels.

These fit well on the roof. I can put 3 on the roof. These will not produce enough power. Thus I have worked out a way to get 2 additional panel to sit under the main 3 panels. 3 panels under is a bit too challenging. This will give us 3 permanent panels and an additional 2 temporary panels. The temporary panels will also act as an awning. The permanent 3 panels will tilt to take advantage of the early morning and late afternoon sun.

The specs for the panels are

Solaria PowerXT- 370R-PD

Max Power (Pmax) [W] 370

Efficiency [%] 20.5

Open Circuit Voltage (Voc) [V] 48.3

Short Circuit Current (Isc) [A] 9.60

Max Power Voltage (Vmp) [V] 40.2

Max Power Current (Imp) [A] 9.20

Power Tolerance [%] -0/+3

Temperature Characteristics

NOCT	[ºC]	45 +/-2
Temp. Coeff. of Pmax	[% / ºC]	-0.39
Temp. Coeff. of Voc	[% / ºC]	-0.29
Temp. Coeff. of Isc	[% / ºC]	0.04

The battery will be a DIY 24v 280AH using 8 EVE cells or similar popular on this forum. At full charge late into the day this will give 7-8 hours of A/C at 600W.

On typical hot day, we would get up, breakfast, go for a walk, pack and drive somewhere to sightsee. Then drive to an overnight location and relax. This would give a couple of hours of early morning sun with 5 panels. Then we will have 3-4 hours with on 3 panels in the sun. Then we will 4-5 hours in full sun with all 5 panels receiving sun. During this period the A/C would be on. The solar output with the 5 panels will be sufficient to run the A/C and continue to top up the batteries as well as normal loads. There will also be power available for cooking. Come late afternoon there would be a full battery and 4200 watts available for running the A/C.

The A/C will be a 6,000 or 8,000 BTU window type A/C. This will be mounted inside the van just below the ceiling and have a ducted inlet and vented outlet to serve the normal exterior area. The van will be well insulated with minimal thermal bridges. Any rear windows will be double glazed. There will be a shade to cover the cab area to reduce the thermal load coming in the windscreen. The unit will be the best energy efficiency available and have a manual soft start.

I am confident that this will work and that we can work with it. The question is how do we get the power from the panels into the battery and then into the 12v loads and into the 240v loads? This where I ask of your expertise and experience.

Into the 12v loads will need a 24v-12v convertor. I am open to suggestion.

Into the 240v loads will need an inverter (an inverter charger will allow shore power option). This will need to be at least 2000w most likely 2400w or 3000 w. Again open to advice.

The main sticking point is the solar charge controller. My research says that I need a 100/85 MPPT unit. The Victron unit is nearly $AUD 1,000 by the time I get it to Australia. I still need an inverter. I compare this to the MPP Solar PIP 3024GK which I can get delivered for $610.



I am not trying to be cheap here. I can see that a Rolls Royce will get me to my destination. So can a Mini Minor. Something in between may be more practicable.

The SCC is based on the input and the output. The input is based on how the array is presented. We have 5 panels. These are in two groupings. 3 only or 3 plus 2 totalling 5.

I cannot see the 5 panels in series. I cannot see the panels in a series of 3 and a series of 2 which are then joined in parallel. This leaves the 5 in parallel. Unless there is another way to do it.

Each panel in cold weather will max at 54.3V and 15A per online calculator. This makes 55v going in and 75A coming out.

Attached the panel array and the panels in parallel.

 

[HRTKD]

The power doesn't have to go into the battery. The solar charge controller dumps power into the system via a set of common bus bars. The inverter is connected to those common bus bars as are the batteries and everything else. If the batteries are full, they won't see any of the power the solar charge controller is providing, the power will all go to the inverter. If there aren't enough watts coming into the system from the solar charge controller then the remaining watts needed will be supplemented from the battery bank.

You could use two solar charge controllers. 3s panels on one SCC and 2s on the other SCC. More expense, of course, but you may get by with two smaller controllers instead of one larger one.

 

[DJSmiley]

For the solar controller, you can look into EPever. The ET4415BND is for example a 45A controller, with a PV input of 150V max.
With 3x370 = 1110W you're at 46A max, but that's in optimum situation, and only a (very small) part of the day. Also, I expect the panels are likely to be flat mounted, not at the optimum angle, so depending on the location they will reach 80-90% of its rated 370W at max.

So with a 45A charger you're good to go, and it's likely it will be <40A about 95% of the time.

Its a lot cheaper, about 300-400 USD.

For the inverter, that MPP PIP looks like a regular household solar thing, so it's supposed to be directly connected to the grid. Many of those require a grid to even power on (they won't power on standalone). Not sure about that specific one tho.

 

[beton]

Thanks HRTKD and DJSmiley. This is info that I am looking for. It comes down being pointed in the right direction and we may have to use a bit of management. Whereas a lot of info points to the largest case. Very few places in Australia are below zero C at 7 AM even in the middle of winter.


I can start with this. I will have a look tomorrow.

 

[Solarfun4jim]

You are lucky to get three 370W panels onto your available roofspace. Because my VW crafter coach narrows at the top so much, the over hang is too much when these panels are mounted across the vehicle...i had to settle on just 2x 370 panels re orientated. :-(
Thought for a long time at doing similar 2 + 2 panels below, but the weight cost was going to be too much to make it sturdy enough.
I opted for victron gear from the off and i wanted longevity out of the products....do not want to be re-visiting this stuff, 5 years down the road. xuba 280's and chargery BMS to disconnect the victrons if anything goes out of whack.

Very interesting and good luck with the build.

 

[beton]

The panels are 64 in x 44 in. 64 in is just over the roof rack rails. They say 150LBs capacity. The panels are the only thing going up there.

 

[Solarfun4jim]

The panels are 64 in x 44 in. 64 in is just over the roof rack rails. They say 150LBs capacity. The panels are the only thing going up there.

Yeah, your promaster is much better in that respect.... much squarer shaped vehicle....mine curves in a lot at the top.
As regards weight, i tend toward over engineer everything for safety, and thus by the time i allowed for substantial 'c-section' runners etc, it just didn't seem worth the risk/weight cost.
I'm just 'over' safety conscious on my particular set up, but i wouldn't mind viewing your finished set up with the two layers of panels, once you have it finished.
I'll be doing minimal work to my build over the winter...too damp and cold here, so will tackle it in spring once temps come up. If i glean anything from your build, i might even reconsider my options on the roof. Fortunately i got a bigger SCC to give me expandability options.

 

[Hedges]

PIP GK says:

"Operating/Storage Temp. 0°C ~ 50°C / -15°C~ 60°C
Operating Humidity 20~90%RH Non-Condensing"

Everyone says "non-condensing". If humid air reaches a cool circuit board, it will condense.
If the board isn't either in a sealed volume or conformally coated, it needs to warm up before being exposed to humidity, or dry out again before power is applied. We use dry air during temperature cycling tests to avoid condensation.

Some of MPP's products (charge controllers) say 100% RH, non-condensing. Still for indoor use. Could be just the spec of another product they acquired.

https://www.mppsolar.com/v3/catalogs/PCM3012_3024.pdf

Inside a house which is climate-controlled around the clock, electronics doesn't see such a bad environment (unless in the bathroom when someone's taking a shower.) For mobile use, I think it needs to be designed and tested for wet conditions.


Powering A/C from rooftop panels means parking in the sun, which adds considerable heat load.
Two pull-out panels as awnings provide some shade, but most of the vehicle is exposed directly to the sun. I also feel a lot of heat standing under my ground-mount arrays.

Maybe additional reflective awnings.
Ideally panels would be deployed in the sun while you park in the shade But that requires a trailer or dolly, and ballast to keep them from blowing over.
PV panels on a tow vehicle and detachable camper or trailer/5th wheel would be one way.
But with your van conversion, I guess you just have to park in the sun and try to shade the vehicle.
Consider having the movable panels on a dolly instead of pull-out on the roof.

Some glaziers have a rack for glass on the side of a van. You could carry panels that way.

 

[Reed Cole]

It kind of makes sense to have two different vans for Australia and Canada since the climates are so different. Good luck with the project.

I live in a temperate climate so it's not too hard to keep my Promaster warm or cool, usually. But if I were more concerned I would have a well insulated curtain or partition separating the cab from the living area and have my sleeping area be able to be partitioned off and insulated as well. I have the same size van and it's quite voluminous.

 

[beton]

Thanks Hedges and Reed Cole. I had considered the heat from the panels. A van is essentially a tin box that will attract and concentrate solar heat. Hence I will be ensuring good insulation and eliminating thermal bridges. I will be elevating the panels above the roof. At least 4 inches, possibly 6 inches. The panels will transfer heat, I have no doubt on that. I am hoping that there will be some dissipation before hitting the vehicle. More so I have yet to see a vanner complain about the heat of their panels onto the roof.
The awning is a different kettle of fish. There will be some heat at the door. If this is a problem, then it is already too hot and the door is shut and the A/C will be cranking. The awning is only 4 foot wide. Not a true camping awning. The principal use is for extra solar. Its secondary use is as a bit of shelter, especially if we are stopping briefly. If I require shade to sit, cook or eat outside, then I will break out a cafe style umbrella.

I like your comment on the condensing. You brought it back to my mind. Humidity is on the forefront of my mind. A moist heat is unbearable while a dry heat is bearable. It is the reason for the 5 panels instead of 4. We need the fan. We will actively be keeping humidity and condensation down in the van. A sack of desiccant will be in the electrical box.

We move forward. I think the toughest part was sorting out how to get the power from the solar into battery. If we can do this with a 45A and a 30A SCC then we are over a hurdle. Then we need to tackle the inverter/charger. This needs to be 24V-240V maybe 2400 W.

I have revised my sketch.
Thanks Beton

 

[Hedges]

You wrote "V" next to the sum of watts by the panels.

45A max next to three panels in series, 30A max next to two? Oh, amperage out of the charge controller. 45A is max (or "nominal"?) for that model. Use a breaker (and wire size) for 25% higher, maybe 60A between charge controller and battery. Except, some brands (Outback, I think) do say no need to oversize.

PV 9.60A Isc, Size fuse or breaker at least 1.56x that (about 15A) so that at better than 100% sun (extra light from clouds) it still doesn't nuisance trip. Just use the value shown on panel label, which is probably 20A. Doesn't actually need over current protection, but breaker is convenient to disconnect.

Of course IR drop in cables to inverter are what matter the most, so make as short as possible.
3000W/24V = 125A, but will be higher at low battery voltage, higher due to inverter inefficiency. Then add 25%. Outback has some breakers around 175A that might work. If inverter has a shutoff control and switch isn't needed, class T fuse is another option.

 

[beton]

Thanks. I will digest tomorrow.

 

[owenfi]

I'm interested in doing a similar design.

I left a comment here (Oct 2, lots of scrolling/loading required) and Nate replied that it's probably best to use 2 charge controllers. If you have a set of 3 showing always and 2 sometimes, then dual MPPT seem like it could save money vs one extra large capacity / there could be performance benefits. I haven't run the numbers yet though.

 

[Hedges]

His experience was that series produced way more power than parallel on bad days, because voltage from 12V panels was too low to charge 12V battery. If 24V panels, that wouldn't have been a problem.
So long as diodes work, series wiring works great. I would use one MPPT charge controller of suitable voltage rating.

It did say, "Regardless of voltage, though, when working with solar panels, it’s a good idea to cover them up or flip them over when possible so they are ‘off’."
I would say, "Don't bet your life on that". It would only take 0.5% of full output from a string of panels to electrocute you. Light passing through cardboard, backside of panel, or reflected light may be sufficient.
MC connectors are touch-safe (but disconnect only with no current flow). Then you can work on the wiring. (covering all panels would drop current low enough to disconnect without burning connectors, just not low enough for safe voltage to touch)

 

[beton]

Hectic weekend. Couple of golf days. Thanks owenfi for directing to Nate. I had seen his work before. I however clicked on his mismatched panels article and he did highlight an issue. Hedges, thanks, has pointed out a bit more to the story. Nate has implied that the 3 series, when paired with the 2 series will act as the 2 series. And as Hedges states any light, no matter how it gets there will activate the lower set of panels.
Thus a 3 plus 2 will be inefficient and the similar as a 2 plus 2.

Which brings to two adages. Never buy a semi trailer for parcel delivery. (Never over design). You can never get value from the area down the side of your house. (Don't waste space).

5 panels in series will not work ( need a real big MPPT). I cannot effectively add another panel to the top of the van. I will need to do an audit of my expected power usage. This will need to be in 2 parts, (1) normal everyday usage and (2) expected A/C usage including time frame. I suspect that 2 by 370w panels will well and truly cover the normal daily usage. I also know that heat is not intermittent. So I will have to allow for the A/C usage be recovered every day.

Fortunately when the A/C is needed, the sun will be shining and the panels will be functioning very well. I am left with having a 2 x 2 system which is easy to install, or a 3 x 3 system which is capable of being done but awkward.

To date I have looked at other peoples A/C accounts. These are few and varied. I have allowed for a 8,000 BTU unit consuming 600wh to cover with the electrical design. A 5,000 BTU A/C is okay to cool the van but you need to be conservative with the use. You need to keep the doors and windows closed and full insulation which we will have and do. 6,000 Btu will be sufficient. The units have to be soft start and manual models. The units will cycle and not average 600whs.

Then it will come down to power management. I will need to get a daily solar production for summer at an average Australian latitude. Then chart the hourly expected solar production. Then apply an average daily power usage to see sunup to 8 AM will full deployment, 4 hours of travel etc with only the top panels operating followed by 3 hours of full sun and 3 hours decreasing to dusk of full deployment. This later period of full deployment will need to cater for normal daily loads for that time, run the A/C and also charge the battery.

Hopefully the 2 x 2 will suffice.

 

[beton]

I just searched and got this for Perth where I live. This is annualized. I will try to get a summer to winter comparison (I did see below). A very rough calculation only gives an average 4,500 watts per day. This may be over 7,000 watts in summer when the A/C is needed. More precise work require.

How many hours a day will my solar​

make decent power?​

Solar on a North facing Perth roof makes 86% of its power between 10am and 5pm (a 7 hour window)

and 55% of its power between 11am and 3pm (a 4 hour window).

Therefore, as the trick is to use the power not sell it, make sure your

pool pump, air con etc are running between 10am and 5pm !!


See a 3kW system example below...

 

[Freep]

Beton, have you looked at slide in truck campers?

 

[beton]

No. In what manner? The sliding mechanism? The slide out panels will need drawer slides to work. They need to slide out clear to avoid shading. 48 inch works. and will need 4 for 2 panels. 60 inch will not slide clear if you can get them to do the job. Then you are up to 72 inches and sticking out. The slides will need to be SS.

Our objective is to get a sound result at an economical price point as opposed to cheap crap at a bargain price or a Rolls Royce system brought on an unlimited budget.

 

[Freep]

No. In what manner? The sliding mechanism? The slide out panels will need drawer slides to work. They need to slide out clear to avoid shading. 48 inch works. and will need 4 for 2 panels. 60 inch will not slide clear if you can get them to do the job. Then you are up to 72 inches and sticking out. The slides will need to be SS.

Our objective is to get a sound result at an economical price point as opposed to cheap crap at a bargain price or a Rolls Royce system brought on an unlimited budget.

We looked at trailers and fifth wheels(caravans) as well as vans before settling on a truck camper and we are incredibly happy with our choice. It has more room than a van, with a shower and toilet, I can stand up inside and I can drop the camper and use just the truck. Plus no towing. Also, since the truck is 4WD we can go a lot of places we normally wouldn't have.

Truck Campers In Australia - Truck Camper Magazine

Garry Davis of Truck Campers Australia reveals the unique Northern Lite models he imports and the lazy axle most Australian trucks require.

www.truckcampermagazine.com