Overland Explorer Expedition Cabin on 2020 Ford F350

[Trail Talk]

Considering upgrading our solar input. While testing the hydronics heating this week, OEV took some data points for battery SOC over 48 hours at cabin temp of 20C/68F. Start was 7am on day 1. The overnight power drop was not recovered during the daytime hours under clear skies.



An interesting 2019 CBC story on the southern Yukon solar utility illustrated a huge drop in solar collection from Nov to Jan.



We have room for another two panels to double our solar collection...in theory. Would appreciate hearing the experience of fellow northerners using solar during the winter - should we expect to see worthwhile gains from expanding our capacity?

 

[IdaSHO]

Solar during the winter is a challenge, for sure.
Especially when the white stuff is coming down in buckets.

I would do some more tests, longer tests.

Id be willing to bet you will begin to see lower draws from the hydronic heating after a few days.
We see a significant drop in LP usage after a couple of days in our custom camper.

I attribute it to everything, especially the water tank(s) not just the air in the camper, finally being brought up to temp.
The mass of these items will help hold and maintain interior temps.
Lower the outside temp, the longer it will take to level off.

For this reason, we do not allow the cabin to drop below a certain temp when on the road in the winter.
A supplementary electric heater maintains temps while on the road.

Still, a bit more solar and/or alternate methods of charging are rarely a bad thing.

 

[gregmchugh]

We have 720 AH of lithium batteries and 1000 watts of solar. Using the rule of thumb of 25-35 AH of battery charge per 100 watts of solar panels, we should get 250-350 AH of solar charging and this is what we get until we get into winter or extended cloudy weather. At the moment in Southern Michigan, with very little sun and getting very little solar charging. We need to supplement it with running our generator every day. We keep the cabin in the 68-70 deg F range during the day and 60-65 deg F range at night.

 

[Trail Talk]

For this reason, we do not allow the cabin to drop below a certain temp when on the road in the winter.

For sure! One of the features of this hydronics set-up is the option to route engine coolant to the cabin while driving. We do use an electric heater with "frost" setting to keep the cabin above freezing while in storage on shore power. The heater was originally developed for calf pens

 

[IdaSHO]

I figured as much. And with it plumbed to operate and regulate temps while driving/running, you're test results will be skewed further.

You might be surprised how LITTLE energy it will use overnight if you roll into camp with it up to temp already.

Still, worst case tests do have their place. Just remember that they are worst case, and not typical.
I aim for a comfortable spot in between worst case and typical with regards to tests like this.

 

[Trail Talk]

We need to supplement it with running our generator every day. We keep the cabin in the 68-70 deg F range during the day and 60-65 deg F range at night.

Thanks for sharing your experience. We only have 340W of solar with room to double that. Considering your 1000W and still needing to run the genny in winter, I'm wondering if we should just go straight to generator power. Optionally, our dual alternators are configured to top up the cabin battery once the truck is fully charged, and one hour of running was sufficient to bring our SOC up from 50 to 65% during our last outing. So I suppose we already have a 445 cu in generator

 

[RAM5500 CAMPERTHING]

Thanks for sharing your experience. We only have 340W of solar with room to double that. Considering your 1000W and still needing to run the genny in winter, I'm wondering if we should just go straight to generator power. Optionally, our dual alternators are configured to top up the cabin battery once the truck is fully charged, and one hour of running was sufficient to bring our SOC up from 50 to 65% during our last outing. So I suppose we already have a 445 cu in generator

Which method is being used for this? How many amps roughly are be putting into the batteries while driving?

Im always looking for options to improve

Thanks

 

[Trail Talk]

Which method is being used for this? How many amps roughly are be putting into the batteries while driving?

Its some of OverlandEx's magic sauce. As I understand, an automatic relay directs the alternator's output to the house batts once the truck batts are fully charged. The same system also charges the truck from shore or solar power once the house batts are full.

 

[gregmchugh]

Thanks for sharing your experience. We only have 340W of solar with room to double that. Considering your 1000W and still needing to run the genny in winter, I'm wondering if we should just go straight to generator power. Optionally, our dual alternators are configured to top up the cabin battery once the truck is fully charged, and one hour of running was sufficient to bring our SOC up from 50 to 65% during our last outing. So I suppose we already have a 445 cu in generator

I would figure out your typical daily power requirements for the rest of the year when you get decent solar power and size your solar array to meet those needs, especially if you tend to stay in place at one spot for awhile. It is nice to not have to run a generator or engine. Assume 25-35 AH per day per 100 watts of solar and you should be good. As long as we are not using air conditioning we can go forever sitting in place with just solar power for most of the year unless we are located in the woods in the shade.

 

[Trail Talk]

Argh, I'm falling down the rabbit hole . This government graphic illustrates annual solar potential by region, using flat-mounted panels as we have on our unit. The band we are interested in configuring for is mid-green straddling the 60th parallel (80-100 kWh/kWp monthly).



When you drill down to the months of Nov/Dec/Jan, solar availability turns bleak. The same region drops into the range of 0-20 kWh/kWp per month!



Solar efficiency can be improved by optimally tilting the panels for latitude and positioning to face South, but that isn't very realistic for a camper unit on the move most days.

I did read an interesting university thesis which studied the effects of cloud and snow on solar panels in Halifax, a location well-known for both. They found that cloudiness decreased efficiency twice as much as snow cover.

Another study done by a local technical college measured the effects of panel tilt vs snow cover in my area. Six panel angles were studied, with a control set left alone and another cleared of snow frequently. While this study didn't include the horizontal position, the trends were useful, at least for the study locale of 53.5º North. They found less loss of efficiency when moving off ideal inclination towards the horizontal than towards the vertical.

All of this nerdiness aside, it seems that for our objective to travel North of 60 during winter, solar isn't feasible. I welcome other interpretations

 

[gregmchugh]

I think you have it right about winter solar in the north, no way to get around it...

 

[shirk]

How long do you plan to stay in one place?

How many days can you currently last on your current battery bank without recharge?

If you are frequently on the move charging off the alternator might negate the need for lots of solar.

 

[Chuck1]

For snow country i think it would be worth it to have tilting panels, far north like alaska the sun is only 6 degrees if i remember right.

if you tilt them to 90 degrees it keeps the snow from piling up on them, and lessens the need to brush them off.

 

[Trail Talk]

if you tilt them to 90 degrees it keeps the snow from piling up on them, and lessens the need to brush them off.

A formula for tilt angle that seems easy to remember is latitude +15º in winter and -15º in summer.

 

[Trail Talk]

If you are frequently on the move charging off the alternator might negate the need for lots of solar.

Yes, absolutely, we don't tend to stay in one place more than a couple of days unless for a specific objective. If I have the math right (2X 200 Ah batteries = 4800 Watt hours @12V) we should theoretically have 2400 Watt hours before taking the current battery bank to 50% SOC. Our only consumers when running dry during winter are the Webasto boiler/fans/circulation pump, 100L fridge, interior lights (LED), nespresso (guilty pleasure), iPad/iPhone recharging, and the trickle to various monitoring systems. Would like to add an induction cooktop as a back-up due to the loss of performance with our propane cooker in cold weather.

Our last two weekend outings didn't allow us to get a proper baseline but now the hydronics are sorted I expect much better performance. Will find out soon. Still, the science suggests we can't physically carry enough solar panels to compensate for diminishing solar radiation during a northern winter, which leaves the generator option.