The electrical guts of the House system

Airedrifter said:

After a month with a single 150watt solar panel, I can categorically say that a single panel is not worth the effort, for my uses.

It gets complicated in that the Ctek charge controller I use has a complicated charging routine -- particularly from 90% to 100% of the battery bank capacity. As it is the charge controller that dictates when to use the electrical sources, I find that the solar panel is only contributing about 10 AH a day. On a 400AH battery bank, that's not a lot. I suppose that it would power led lights and charge a phone, but it had little contribution to the powering the fridge or microwave.

It's been an interesting learning process and I now know a good bit more about monitoring an electrical system. However, for my purposes -- where most of the roof area is used by a platform rack -- solar is meh...

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orton said:

You have covered the problem. 150 watts is not enough and you need the roof space to install the correct size.

I have a single 300 watt panel with a MPPT controller and it provides all the power I need. Do have a backup charging method if weather conditions force its use which is almost never. Of course it depends on where you live and your power usage. Solar panels are not too useful when covered by a foot of snow.

I have a 85 liter refrigerator, a microwave and the usual LED lights and water pump. Highly recommend a "state of charge" meter so you know what SOC the house battery is at.

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orton said:

A little background:

Originally installed a 135 watt panel on the sold 08 Sprinter because that was the largest panel size that could be shipped UPS to avoid high shipping costs. That panel would almost keep up with my power needs if weather was full sunlight.

Removed that panel and installed a 205 watt single panel. That panel would keep up with my electrical usage in good weather.

Sold Sprinter after 5 years and started a second conversion. Transit has the same physical size panel but it is rated at 300 watts. Used the same electrical components as the Sprinter had. Single 255 amp-hr Lifeline 8D AGM battery, Magnum Energy MMS1012 inverter/charger/transfer switch and a 15 amp Morningstar Sunsaver MPPT solar controller. Same results in the Transit that I had in the Sprinter. Almost no need to use any charging other than the solar panel.

I do not directly connect the house battery to the vehicle battery for charging for a number of reasons. I do have two backup methods of charging. I can use the house inverter/charger to charge from shore power or from "shore power" from a 1000 watt inverter powered by the Transit 12 volt system. Have not used either backup yet on the Transit. In fact just completed the wiring so I can now do that if I ever need it.

My normal SOC overnight was 93% in the morning with the Sprinter. Sprinter had a 80 liter Dometic compressor type front opening refrigerator. Bought a Vitrifrigo 85 liter front opening refrigerator for the new Transit build. It has the same compressor but instead of a coil on the back of the refrigerator it has a radiator and small fan similar to what chest type refrigerators use. Now my SOC in the morning is 95% to 96%. Apparently the different design uses less power.

My refrigerator install is different than a lot of conversions. I make the cabinet larger so I can add additional polyiso insulation around the refrigerator. Transit has 3" additional insulation on top, bottom and the sides. Since coil is not on the back I glued 2" of closed cell foam on back of the VItrifrigo. I also have a 4" square hole in the van floor directly behind and below the refrigerator. Cooler air flows through the floor hole to the refrigerator and out the unpowered open Maxxair roof vent. In addition I do not heat the van at night. I let van interior get cold at night and I stay warm with a 12 volt heating pad. Refrigerator runs less in a cold van. When I used the 600 watt (1140 watt actual) microwave in the Sprinter it used 1% of my battery capacity for every two minutes of use. Bought different brand 600 watt microwave for the Transit. Almost identical microwave but it only draws 950 watts. Think they were both manufactured my same company with different brands but new one has been improved.

So I do have a few years worth of using the systems.

Last August I spent 5 days in Monterey with 75% overcast sky's. Pulled into my driveway after the 5 days at 100% SOC. No charging other than solar. In October spent 5 days camping in Paradise Ca. Parked in a total shade location. Did take one ride with the group when van was in the sun for several hours. Got down to 83% SOC. Could have used the vehicle powered inverter to charge but it was not yet wired. Last day it rained and on the drive home it rained. Turned off the refrigerator when I got home. Took 6 days to get back to 100% SOC in rainy weather. It gained about 2-3% each day in the rain.

As I said before we all have different weather and use different amounts of power. So the results will be different for each of us. I do know the single 300 watt solar panel does work for my application.

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Airedrifter said:

So, I went on a 10 day trip. 1701 miles.

This was a typical river/outdoor type trip for us with the bonus of an eclipse. There was me, my wife, my 13yr old son, and 2 of his friends. We were on 3 different rivers on 4 different days, we had 3 serious hikes and one nice stroll in Joyce Kilmer, we stayed in a hotel 2 nights, we stayed in our friends' driveway 2 nights, 3 nights in campgrounds (one with power), and three nights in the boonies without any amenities.

The boys (and I) were tough on the electrical system. (the solar panel got it's first walk on -- no damage). The boys had lots of "electronics" that need charging and they got 3 hours a day of game time on the game console. At the eclipse site, we had a bunch (maybe 10) of people using the various charging stations. And the dimmable rack lights were a big hit. Everyday, excepting one day at our friend's, the van moved. The battery bank stayed above 70% most all the time, though the Sunday night before the Eclipse, after only a little driving on Saturday and no charge excepting some sun, the batteries dropped to 48%. I started with 400ah of battery bank, but in loading for the trip, I just didn't like how the new batteries got in the way and didn't have time to remount them, so we only took 200ah. The 400 would have given us plenty of reserve so as to make charging a non-issue.

I'm guessing that we used about 60ah a day. The one day we had the battery bank run down some and parked it in bright sun, the solar panel contributed 22ah! That's an installation record. I'd say the solar panel averaged a bit over 10ah of daily contribution. I saw several at 6 or 7 and several at 12 to 14. (I note that the Ctek blends the solar panel charge with either shore power or alternator power. The day we got 22ah from the solar panel was a day we drove over 300 miles.) I have a 100 ah battery in our adventure trailer. I use it to run blowers for the rafts and a fairly elaborate indoor and outdoor lighting system in the trailer. The trailer battery has a Ctek 7amp ac charger. One day, we charged it from the van inverter.

All in all we're happy. I see a need to do some work on changing and incorporating the OEM dome lights into our switch panels. It will be a good lesson in switch logic.

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