Solar question

calewjohnson · 09-05-2015, 11:03 AM

For those with solar installed, if I am connected to shore power and can produce enough solar power to run the trailer during the day, are the systems smart enough to do this (like a residential install) or is it split as shore power only and solar only?

Thanks,
Cale

**wahoonc** · 09-05-2015, 03:42 PM

Most of the installations I have seen aren't that smart. Easy way out would be to flip the breaker for the converter.

Aaron

**wahoonc** · 09-05-2015, 04:50 PM

I have seen some pretty involved installations on things like buses with big inverters and auto disconnects, but they were running huge battery banks. On most RV's that I have dealt with; the typical install is a 12v solar array ~100-200 watts that charge up a dual battery setup. If you plug into power the converter and the solar charger top the batteries up until they both go to float mode.

What would make a slick circuit would be some sort of photocell controlled relay that would cut the control circuit of the converter while the solar panel was active.

My typical system is 160/200 watts, 30 amp controller and dual deep cycle batteries.

On the next planned go around... the RV will most likely come with 160 watts installed, then I am going to add an adapter to be able to plug my 100 watt portable unit in. On a sunny day in the winter I will charge back up quicker, on a hot summer day, I can park in the shade and still charge back up. Best of both worlds!

Aaron

sundancer 87 · 09-05-2015, 05:54 PM

Quote:

Originally Posted by wahoonc

I have seen some pretty involved installations on things like buses with big inverters and auto disconnects, but they were running huge battery banks. On most RV's that I have dealt with; the typical install is a 12v solar array ~100-200 watts that charge up a dual battery setup. If you plug into power the converter and the solar charger top the batteries up until they both go to float mode.

What would make a slick circuit would be some sort of photocell controlled relay that would cut the control circuit of the converter while the solar panel was active.

My typical system is 160/200 watts, 30 amp controller and dual deep cycle batteries.

On the next planned go around... the RV will most likely come with 160 watts installed, then I am going to add an adapter to be able to plug my 100 watt portable unit in. On a sunny day in the winter I will charge back up quicker, on a hot summer day, I can park in the shade and still charge back up. Best of both worlds!

Aaron

When you get ready for the photo cell relay scheme let me know, I'll build it for you.

MartyG · 09-06-2015, 01:17 AM

Quote:

Originally Posted by wahoonc

What would make a slick circuit would be some sort of photocell controlled relay that would cut the control circuit of the converter while the solar panel was active.
Aaron

Aaron, I don't know too much about solar outputs, but wouldn't the reverse work better, i.e. a relay is held open by 120VAC, but closes upon lack of shore/generator power to allow the solar output to flow to the batteries? It seems, because of the regulation of the converter, that it's controlled output would better serve the batteries when available. When not available, the solar output, variable by nature of lighting, clouds, etc, would be used. Your thoughts?

**wahoonc** · 09-06-2015, 01:22 AM

Quote:

Originally Posted by MartyG

Aaron, I don't know too much about solar outputs, but wouldn't the reverse work better, i.e. a relay is held open by 120VAC, but closes upon lack of shore/generator power to allow the solar output to flow to the batteries? It seems, because of the regulation of the converter, that it's controlled output would better serve the batteries when available. When not available, the solar output, variable by nature of lighting, clouds, etc, would be used. Your thoughts?

The solar controllers that I have dealt with in my RV's actually seem to do a better job than many converters on taking care of the batteries. I have seen converters crap out on short notice and boil a set of batteries dry in a matter of hours. Never seen that issue with a Solar controller. I have had a few that didn't want to maintain set points, but they seemed to fail in the the other direction, and not provide enough power to keep the batteries up. IMHO I would prefer the solar to be the default during daylight hours.

Aaron

VCToyhauler · 09-06-2015, 01:57 AM

It can be done but you have to provide the "smarts"... I had an RV electrician set up a sub panel to isolate the inverter so it could be turned off, and not break or feed back when gen/shore is available, yet can run everything from stored solar power (except A/C) when gen/shore is not available. I was not able to find a plug and play solar-to-inverter-to-panel solution that would play nice with the stock transfer switch. All worth doing an results in less gen & gas use. Also less propane use, if you put the fridge on A/C when you are shedding excess solar power. Just be sure to switch fridge back to LP before dark, and always have a spare battery to start the gen just in case.

MartyG · 09-06-2015, 04:24 AM

Quote:

Originally Posted by wahoonc

The solar controllers that I have dealt with in my RV's actually seem to do a better job than many converters on taking care of the batteries. I have seen converters crap out on short notice and boil a set of batteries dry in a matter of hours. Never seen that issue with a Solar controller. I have had a few that didn't want to maintain set points, but they seemed to fail in the the other direction, and not provide enough power to keep the batteries up. IMHO I would prefer the solar to be the default during daylight hours.

Aaron

Thanks! I figured you'd have an informed answer!

Marty

**wahoonc** · 09-06-2015, 11:47 AM

For the smaller, simple trailers like mine.

All you really need to do is walk over to the all-in-one converter control center and switch the converter off at the breaker panel. That might be the easiest method, run a switch to cut power to the converter.

I know the PD I just got has the ability to allow power to the battery or not via the battery disconnect switch depending on how it is wired up. Maybe that circuit could be utilized too.

Aaron

calewjohnson · 09-06-2015, 12:18 PM

Thanks for the replies...I was thinking about all the open roof space, which one could nearly cover completely with panels. I figured doing so would allow for a lot of power to be produced. The one thing I did not think about was the AC. It may be a stretch to have enough batteries and solar to keep up with that power requirement.

Cale

**wahoonc** · 09-06-2015, 01:12 PM

Quote:

Originally Posted by calewjohnson

Thanks for the replies...I was thinking about all the open roof space, which one could nearly cover completely with panels. I figured doing so would allow for a lot of power to be produced. The one thing I did not think about was the AC. It may be a stretch to have enough batteries and solar to keep up with that power requirement.

Cale

I have not seen a solar power system that could run an A/C system for very long due to the massive wattage draw. Most solar systems are used by people that either dry camp/boondock or to keep batteries charged while in storage. However! I have a hybrid Ford Fusion that has an electric powered AC system on it that does operate on battery power. No clue on the specs of the system, just know that it works. There are much more efficient AC units than the current RV units. I know of more than one person that has ditched the roof tops in favor of the mini split units.

I recall one bus that had something like 2,000 watts of solar and a 16 battery bank to provide power. They also had a diesel generator...

You can do anything you want, all it takes is money and perseverance.

Aaron

ewarnerusa · 09-06-2015, 03:57 PM

No need to worry about multiple charging sources, they all play well together. Although the voltages that the various sources are applying may trick and undermine the others, no harm is done. Continuous solar input through a smart solar controller with proper voltage setpoints and temp compensation can do a fantastic job of keeping batteries healthy and fully charged all on its own.

I have my converter switched off at the breaker panel and actually haven't had it on in ages. It is our backup charging source.

calewjohnson · 09-07-2015, 01:23 AM

Thanks for the input...I was hoping that the system could be setup to use mainly solar and supplement t from shore power as needed, thus reducing our power bill. Aaron is right, anything can be done, however, I would blast through what little cargo weight I had left... Plus, I do not want to try to re-engineer what they could not put together correctly in the first place.

Cale

**wahoonc** · 09-07-2015, 01:32 AM

Quote:

Originally Posted by calewjohnson

Thanks for the input...I was hoping that the system could be setup to use mainly solar and supplement t from shore power as needed, thus reducing our power bill. Aaron is right, anything can be done, however, I would blast through what little cargo weight I had left... Plus, I do not want to try to re-engineer what they could not put together correctly in the first place.

Cale

Well if you run your fridge on propane and live without AC your power bill would go way down. But the last time I checked electricity was still cheaper than LP. In fact one of the much discussed winter "tips" is to use electric space heaters at the southern campgrounds instead of the LP furnace to save money. Apparently quite a few of those campgrounds don't have metered power.

Solar is great stuff, if it is set up properly and sized to meet your needs. But in does require lifestyle changes if you plan to use it as your main power source. For us, in the Deep South air conditioning is a necessity, not a luxury. So we camp where we have power to run it, when we need it.

Aaron

VCToyhauler · 09-09-2015, 02:40 AM

I have a fairly large solar setup, and it can run everything - except for A/C. Going in, that was a goal, but is not practical. If we need A/C, we fire up the gen. To run A/C off elec, I would have to double the inverter, charge controller, and batteries, and would still be limited in time.

donzinger · 09-09-2015, 07:51 AM

Quote:

Originally Posted by calewjohnson

Thanks for the input...I was hoping that the system could be setup to use mainly solar and supplement t from shore power as needed, thus reducing our power bill. Aaron is right, anything can be done, however, I would blast through what little cargo weight I had left... Plus, I do not want to try to re-engineer what they could not put together correctly in the first place.

Cale

Cale - I have a pretty decent solar/inverter setup. In my opinion, about the only thing it will do to supplement you is in charging the batteries and running the lights. Will it save you some coin? Yes. Enough to justify the install? Up to you. I mainly went with the solar setup because we dry camp a few times a year at NASCAR races and it is awesome to be run both refrigerators, the ice maker, fans, TV, satellite, stereo, etc all day long and refrigerators and fans through the night and still be able to make coffee in the morning before worrying about the batteries going dead before the sun takes over again. Only time we run the generator now is for AC on hot nights when too uncomfortable to sleep.

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