Hybrid Solar / Shore Power Solution Wanted

[airmon]

I don't know of any existing products that do what you want, but it would be pretty easy for someone to rig up an automatic switch that would switch shore power on or off based on certain criteria.


Use a Xantrex LinkPRO power meter to monitor battery state. It can be set to monitor either voltage and state of charge, triggering an alarm and a relay when the power gets below the set point.

If, for instance, you set the LinkPRO to turn on your shore power when the batteries were 30% discharged, as long as there was enough solar power coming in to keep the batteries charged, your shore power would be off. Once the SoC dipped below your set point, shore power would turn on, supplying power and charging your batteries. Additionally, you could set the voltage alarm fairly high ( 11.5V? ) so if you turned on a large drain, like using a microwave oven on the inverter, shore power would also kick on, even if SoC was high.

Use a few solid state relays to control the incoming power, like these - High Performance Solid State Relays
No moving parts, handles 50A and can be triggered by anywhere from 3-36V, with triggering current low enough that the LinkPRO's relay output can handle two of them, one for each leg of the 50A plug.

You could add an override switch that would manually turn the power on as well.

The practical result is similar to what you wanted.

In my RV, when plugged in, the inverter/charger passes-through power to all of the interior outlets. When there is no shore power, the inverter makes power for all of them from the house batteries. The water heater and A/C are directly connected to the shore power.

If it were me ( and now that I thought this idea up, it might be... ) I'd wire it
so only the inverter/charger gets turned off. That way, the appliances that can't be solar in my RV ( water heater, A/C ) are never switched off, but in temperate weather all the little stuff can run off solar will, as long as there's an adequate battery charge.


The LinkPRO instructions are here if you want to see how to set it up-http://xantrex.com/documents/Accesso...-01_rev-C).pdf
Check out section F2 for battery alarm specs.

[terry735001]

like every one says you need a grid-tie inverter like what i have

my RV well send power back in to grid

and giving its on a RV or some thing that moves you get to pass alot of the red tap the power Co well make you do

i do it here in FL on a 24v DC SW inverter

[pasdad1]

You would need to be certain your system didn't "back feed" the campground electrical system during a power outage. Could kill the electrician trying to make repairs, thinking the power was "off".

[Reed Cundiff]

Airmon has some good ideas as usual but we (our son) handled it differently

We can use line power either of two ways

1. The 50 amp system is tied only to the alternating power (110 V) system. The original converter has been removed from the system. This basically means micro wave, a/c, water heater if we ever did use it. It does not power the battery suite. Tossed the 50 amp cable a year ago and may toss the 30 amp replacement as we have not used it in 13 months except to test the system.

2. We burned out microwaves in lower Baja and in Yucatan. The power can be really dirty as one guy checked the power in Yucatan and it bounced from 85 to 145 V. We had a surge protector but it turned things off more than they were on. Son came down with family to spend a week with us on beach and brought down a battery charger. The 110 went through charger to batteries (than a suite of four glass mats) to inverter (2.5 kW PSW) to system. Things worked great.

He then did the same thing in design and fabrication for current system. A 15 amp cord goes to the battery chargers to the 48 V nominal battery suite (9.6 k-hr LFP) and then through 4.0 PSW inverter and converter to 12 V system. This has worked well the two times we used it in 101 F heat.

I doubt that anything would backfeed the system as Pasdad1 has noted might happen with other concepts

Reed and Elaine

[airmon]

We do something similar on occasion by flipping the breaker that powers the inverter ( passed through to almost all the outlets in the RV ) and run on battery/solar power alone.

Mostly we've done it when we're driveway surfing and pulling power on an extension cord and have a big voltage drop when we use the microwave, which then fails to work well. So we switch off power to the inverter at the breaker in the 120V box.
So we disconnect, draw 11A from the inverter ( and 125A from the batteries ) for a few minutes. We reconnect when we're done heating something and let the extension cord recharge the house batteries - the charger side of the inverter draws at most about 8A.

We've also flipped the incoming breakers and disconnected the whole RV when there's a serious thunderstorm, just to prevent surges.

[SteveUpp]

I found a partial solution to my problem. I was reading Technomadia this morning and came across an article on a Boosted Inverters. After reading his article and then looking closer at the MSH-M series of Inverters from Magnum Energy I think I have found a partial solution.

The MSH-M inverter is a hybrid inverter that will use battery power to boost the incoming AC from shore power to power loads in the RV when the incoming AC is insufficient by itself. But that is only one mode that the Inverter supports. The second mode applies to the situation I was asking about. The second mode is called "Load Support VDC" in which the an external DC source (e.g. Solar) is providing more current than is needed to charge the batteries. When this condition is detected, the inverter automatically uses this excess DC current as power to supply the AC inverter thereby decreasing shore power usage.

So in effect, when the battery bank is fully charged and there is excess solar energy available, the Hybrid Inverter will pull current from the Solar Charge controller to supply the AC loads in the RV, until the solar capacity is insufficient to meet the AC load, at which time the shore AC power is 'added' in.

Very cool! The MSH series inverters are physically the same as the MS series which is common in many MHs these days. If you have solar now in an RV that has an Magnum Energy MS series inverter then switching to an MSH series inverter allows you to utilize less shore power and improve your green power usage with very little work. I wonder if there's a market for used MS series inverters

[Gocoffeer]

Steve: I used the VSHEETS suggested install. Vince was kind enough to help motivate me throughout my entire install process and I completed the solar and wiring portion of the project. What I have done a bit differently from the norm...I installed a complete parallel system and separated the solar (as you have suggested) from the RVs wiring. It is a complete pain in the rump to install a new wiring system and additional duplex receptacles but it is doable. Microwave,,,refrig,,,TV and electronics,,,and some additional bedroom and front end boxes were added. I have a 3000w Pure Sine inverter and several smaller inverters that run different systems as needed. As the day grows shorter as winter approaches... I get to see how much a 500w solar unit can really handle...