solar on/off grid installation

[dabedwe]

I just bought a nice pull behind camper and would like to install some solar panels on it to make it more self contained as well as tie the system into my home when it is just parked. I have tried to find a video online or even a diagram explaining how to wire this up, but all i can find is off grid installation information for campers and rv's. I want to be able to plug my camper into shore power and still run the solar set up when that is not available. Additionally, i would like to use the panels as a tie in grid system for my house when i am not on the road. I am not sure if i need to buy a separate inverter and install a switch that will cut the power to the camper when i plug the solar panels into my house outlet to feed my home system. I plan on buying an mppt charge controller and 400 to 500 watts of solar panels.

Can i just connect the load to the ac input in on my camper fuse box? i do have a free breaker slot available that i could connect the load to if that will work. If so, can I still plug the camper into shore power while the solar system is running? If i use the free breaker slot, i could just flip the breaker before i plug the camper into shore power if i need to. Additionally, if the breaker slot installation will work, can i use the existing shore plug to feed the power to my house or do i need to cut the feed (basic switch) going to the trailer charge controller from the solar panels, connect them to a second inverter, and then run a new plug from that inverter to plug into my home outlet for tie in use? If i can connect the load to a breaker in the camper fuse box, would i need a separate inverter or could i just run a second load wire with a plug from the charge controller to feed it back to the grid?

I realize there is a lot of questions here. depending on how i need to install this system may make some of them irrelevant. However, I would appreciate any advice on this.

[dabedwe]

JiminDenver wrote:
I have to ask what is the 1000 BTU air conditioner? I use our solar to run a 5000 BTU A/C pulling 450w.

It is a American Comfort ACW100 1,000 BTU Portable Personal Air Conditioner. they actually discontinued them, but mine works great. You can only use it in a very small space, which is probably why they were discontinued. They are perfect for small campers. You still might be able to pick one up if you look around on the internet. My camper is only 14', so I do not need much to cool it down.

[westend]

I had to look it up, too, Jim----personal space air conditioner

[JiminDenver]

I have to ask what is the 1000 BTU air conditioner? I use our solar to run a 5000 BTU A/C pulling 450w.

[westend]

Yes, as long as you have at least 250 AH of batteries to store the charge.

[dabedwe]

To really hit on specific advice, share what you have now and how you use your RV.

right now power really is not an issue. the places i have traveled have power hook ups. However, there are some places i want to travel were i will not have an external power source available. With the panel array that i am looking to purchase, I am sure i can get by with 3 or 4 batteries. I do have a 1000 btu portable air conditioner that uses 250 watts. I would not use this often, but i would like to have the option if i find myself in a place with no power hook ups. I might only find myself in this type of scenario once or twice a year and just for 2 or 3 days. I do have a 24" flat screen tv in my camper, but i also have a nice laptop that i can use when if power is an issue. I have limited space on my roof. My camper is only 14' and i have a 8000btu ac, antenna, bathroom fan, and a few other things on the roof. do you think 400 or 500 watts of panels would charge enough batteries to run a 1000 btu 250 watt ac for 6 hours at night? other than the ac, i would only need panels to run lights, a radio, charge a cell phone or laptop, maybe run the tv occasionally, and stay in when the power goes out in my house (i live in the midwest and it happens multiple times a year).

[westend]

i do have a converter in the camper that converts dc to ac. It is just a standard camper converter system.

A standard RV converter converts AC to DC. 120V-> (nominal) 12V. Progressive Dynamics is a well respected brand name for RV converters. I have one that is still operating well at 44 yrs. old.

To really hit on specific advice, share what you have now and how you use your RV. Calculations of power use is especially helpful.

Typically, the output of the solar controller is fed into the batteries, directly. Since even a modest system is producing 20+ amps at 14V or so, cable dimensions should be on the larger side. I often suggest to upgrade the onboard converter wiring to the battery at the same time solar is installed. For those using solar, some also use a generator and squeezing the most out of generator run time with just a cable replacement makes economic sense.

Here is a list of Forum member solar installations There are many good ideas pictured and explained in the threads.

[dabedwe]

Gavin60 wrote:
The Enphase system is all plug and play.

I like the idea of the Enphase system. I have read that linked panels can all go down if one gets some shade. I assume you can also run into problems if you have some kind of defect with a panel. I am definitely going to take this into consideration when i purchase home systems. thanks for the info!

[dabedwe]

I appreciate all the feedback that i have received on this post. When i first decided that i wanted to do a solar system for my camper, i assumed that the mppt charge controller load output was ac. I did not realize that you needed an inverter. from the cheap full systems i have seen, the inverter is left out. I guess these are strictly for off grid installations only. I definitely want some decent equipment. I only asked about hooking the load from the charge controller to an ac breaker due to the fact that i assumed the load was ac. Since the load is dc, i think connecting it to the dc side (fuse box) would be more beneficial now. there is no reason to convert 12v to ac and then back to dc. most of the equipment i have is ac/dc. the air conditioner unit and the microwave are the only thing that runs strictly off ac power. i do have a converter in the camper that converts dc to ac. It is just a standard camper converter system. I have been thinking of replacing the whole unit with something better (if anyone has suggestions for better quality replacement unit let me know). So now that i have been enlightened. Sould i hook to the load off the mppt charge controller to the dc inputs on the fuse box or should i forget that setup completely and just connect the new battery bank that is connected to the mppt charge controller dc output in a series with the original battery that is on the camper? Just connecting the new batteries from the charge controller to the old battery would actually simplify things and may be the best option for me. I now feel like i have been making this installation more complicated than it really needs to be 🙂

[reed_cundiff]

We have a LFP battery suite. LFP should not remain at high float for extended periods of time (3.4 V per cell) and keeping an LFP suite on continuous charge from line power will degrade the cells. Chris of Technomadia candidly writes about the problems they had with his in his write-up of 3.5 years of LFP usage.

For this reason our son designed and fabricated our system so that the original 50 amp inlet system is isolated from the battery charging system. The 50 amp system (which we have not used in two years) will only run the AC appliances: hot water, micro-wave, air conditioner. The original OPM converter is only used to supply power from the battery suite via the 508 W Mean Well 48 to 12 V converter. We have tossed the 50 amp cable and its replacement 30 amp cable since we have not used either in two years except to trial the system.

The battery suite can be charged via a 1.5 kW battery charger and a 15 amp (120 V) extension cord. We have used this once when it was 103 at an RV park in Spokane (were visiting relatives and no place to boondock) and we were in the shade and really wanted a/c.

Daughter has about 6 or 7 kW of solar, brother-in-law has around 3.1 kW and son has around 5 or 6 kW of solar.
Reed and Elaine

[Crazy_Ray]

Roy when are you going to get your Solar? What brand are you looking for? I waited 5 years, bought 1 panel at a time and have ended up with over 500 watts. Love my solar. :B

[RoyB]

I have a so called duty 600WATT PURE SINE WAVE INVERTER off my battery bank. I went the simple way and run two extension cords from the 600WATT INVERTER with one multi-head receptacle going to the home entertainment area and the other multi-head receptacle going to the bedroom area. This is always ON when we are camping.

When I finally get my SOLAR PANELS installed they are only considered to just charge my batteries in high sun to keep me from having to run my 2KW Generator so much doing the morning re-charge of the batteries.

I went the baby steps way learning how to live off the batteries and how much capacity I really need to do our style of camping off the power grid.

Now that we are very successful now doing this I am ready to add solar panels to improve on it. Solar Panels and Generators here on the East side of the USA has to be considered differently than what the West Side of US folks have to deal with. We generally have less HIGH SUN and definitely have to deal with GENERATOR RUN TIME restrictions just about everywhere we go... Not that many DISPERSED camping areas near us...

Roy Ken

[KD4UPL]

I install both off grid and on grid solar systems for a living. What you want to do is not advisable, not very easy to achieve, and likely will take many many years to recoup the costs involved.
To legally connect a grid interactive solar system in your home you need to sign up for "net metering" with your power company. They will likely will require an AC disconnect switch near your meter that meets their specification. You will also need to have your installation permitted and inspected by the local jurisdiction. You will need to use UL listed equipment that is certified for grid interaction. Many power companies require that a licensed master electrician sign off on the installation on their paperwork.
Are there lots of people who set up illegal grid tie solar systems without doing all of this? Yes. Could they potentially kill a lineman with their system? Yes. Transformers on power poles work both ways. If the line in front of your house is 24,000 volts the transformer steps it down to 240v for your house. If your solar system is feeding 240v into a dead power grid the transformer will turn it into 24,000 volts and send it out on the lines.

In your RV, no you can't connect the charge controller to the AC breaker panel. Charge controllers output is DC and needs to be hooked to a battery bank. You would then connect your battery bank to your AC panel thru an off grid inverter.

If you really want to make the sytem work both ways the best way is to install 2 60 cell panels on your RV. Their Vmp will be around 30 V DC. This will require an MPPT charge controller in the RV. You would also need 2 micro inverters like an M250 from Enphase. You would need a way to have the panels feed the MPPT charge controller when camping and the Enphase inverters while parked. This would require a 4 pole double throw switch arrangement. The output of the micro inverters would need to travel thru a completely separate 240v circuit that would leave your camper, go thru the power company disconnect, and tie into a back-fed breaker in your home's panel.
I find it hard to believe such an arrangement would be very easy to get permitted and inspected but it may be possible.
When all is said and done, if you had 500 watts of solar mounted flat on your camper and tied to the grid every sunny minute of the year you would make about $75 dollars of electricity per year, depending on your power rate.

[JiminDenver]

First thing is call the power company and see if they accept grid tied and how they handle it. Most importantly what fees and rates do they charge people with solar. It may decades to recover the cost of hooking it up with as little power that you will be producing.

I also think that you will find they want a permanent installation and will not be interested in panels on a RV.

Another way of doing it would be to plug a extension cord into your RV inverter and run things in your house. I could set my 750w system up here at the house and run my fridge off of it. That would put a dent in our power bill. Unfortunately it would also be cycling my battery bank daily and I would have to save enough on bill to replace them faster than usual.

So check into it and see if it feasible. Solar on a RV is wonderful and worth every penny just to not listen to a generator. Grid tied can be complicated and expensive.

[azrving]

Gavin, love your story and I'll check out micro sometime. Thanks

If I wanted to use my rv solar system I think I would run an extension cord into my house in a neat manner and maybe power the frig or something and keep it real simple. 520 watts is great on my rv but I cant see it doing much for my house.