Solar panels first, shore power second, no switches.

I'm full time plugged into an RV park's shore power in California.  The prices of electricity keep rising and I'd like to offset the price of electricity from the shore power with an array of solar panels placed on the roof of my 5er, like a grid-tie... skipping the batteries if possible.  My 110v outlets only work on shore power currently.   

I'd like to have power used from solar panels first and then use power from the shore power if the panels aren't enough. I don't want any manual switches or pulling chords, it should be self regulating. Let's keep this thread focused on the how-to rather than numbers.

I did see these units, but I'm not confident in the workmanship: Grid Tie Inverter https://shorturl.at/fLSU9

Kevin Means, a member here just did a grid tie on his California home. There's a lot more to it than getting equipment and hooking it up.

Grid tie requires a permit and I can?t imagine the utility would let an RV in a park grid tie

This is a really complicated issue because of the differences in residential Solar and Battery based Solar.

Not to mention the legal complication of such issues as leasing equipment, ownership, buy back rates, and what happens if you sell the domicile that has the solar installation.

I would say that the most important consideration in the scenario that you presented would be to carefully manage consumption on a traditional RV Solar setup and then only use the A/C connection of you have to.

That barely scratches the surface of the subjects that are involved in this discussion.

Grid-tie solar is complicated, since you're feeding power back into the grid you need regulatory permission and safety devices to make it work.  It will be complicated if not impossible to get a grid-tied system approved for a potentially mobile device like an RV that's not permanently connected to the grid but connects via a removable plug and socket.

Your most practical alternative is to set your RV up to be self-contained, like people who boondock using solar power without an electrical connection.  The solar panels charge a battery, then as needed an inverter changes the 12 volt DC battery voltage into 120 VAC to feed your outlets.

So yes,you'll need one or more batteries as a place to store the surplus solar power until you can use it.

The difference between what you want to do and someone who is boondocking is solar doesn't have to supply 100% of your power, if you use more than what the solar panels can supply, the excess will come from the grid via the 12 volt converter.  But you'll only pull power from the grid when your demand is over and above what the solar panels can supply.

baywardboondocker said:

I'm full time plugged into an RV park's shore power in California.  The prices of electricity keep rising and I'd like to offset the price of electricity from the shore power with an array of solar panels placed on the roof of my 5er, like a grid-tie... skipping the batteries if possible.  My 110v outlets only work on shore power currently.   

I'd like to have power used from solar panels first and then use power from the shore power if the panels aren't enough. I don't want any manual switches or pulling chords, it should be self regulating. Let's keep this thread focused on the how-to rather than numbers.

I did see these units, but I'm not confident in the workmanship: Grid Tie Inverter https://shorturl.at/fLSU9

Click to expand...

well, the "how to" is called a "grid tie zero export controller".. however, no POCO will endorse such a thing and paid for politics has ensured that you can't do it without jumping through hoops and performing fellatio on those that make the laws. POCO's are in the business of making money and for you to do something like this "on grid" is alien to them. grid tie Net metering is common in a lot of states but the equipment required must be approved and installation has to be done by licensed electricians.  also, the POCO will charge you a monthly fee for this "privilege" especially in CA.

here are some numbers you didn't want to see..

let's say you buy 2000 watts of solar.
in SoCal you will generate a yearly average of typically 5.4 sun hours per day. so over a year
you could generate 365 days x 2000 Watts x 5.4 hours = 3942 kW/hrs of energy best case.

if you currently pay 16 cents per kW/hr then you will generate 3942 x 0.16 =  $630 per year revenue
so at $2 per watt install it's 6 years before you break even. that does not include the POCO fee, even if you can get this approved.

grid tie works best with larger arrays and high cost areas like Hawaii..

having said that, there are some non approved grid tie inverters sold from China, they are illegal for use in the US, in fact most of the western world ! they do work quite well ( I have tested one out of curiosity ) but they lack the necessary safety mechanisms
to protect your house/RV from burning down.

sorry for the bad news..

Hi thanks for the responses. Not what I wanted to hear of course. 

They did just update all the power meters in our park with the new fangled digital ones, so I'm sure it can handle back feeding (without sparks flying, at least).

I'm surprised no-one has had experience with one of these in an RV.  It literally looks as simple as plugging the solar grid into these stackable grid tie inverters and then plugging those into a 100v outlet in the RV. 

If anything can be said, there seems to be a severe lack of any blog postings or youtube videos sharing the results of using these devices.  The few I have seen for residential seem to be really positive.

https://www.amazon.com/Inverter-Stackable-DC20-45V-AC90-140V-Output/dp/B07281BDDY/ref=sr_1_8?s=lawn-garden&ie=UTF8&qid=1530769955&sr=1-8&keywords=grid+tie+inverter

BTW, my monthly power bill here in CA is in excess of $200 a month, and I don't even use air conditioning.  So anything I can do to lessen the bill with my own equipment is going to pay for itself faster in this region.

All I can say is be careful.

Before you just plug it in get a qualified opinion locally.

That piece of equipment is not the solution for your power needs.

baywardboondocker said:

Hi thanks for the responses. Not what I wanted to hear of course. 

They did just update all the power meters in our park with the new fangled digital ones, so I'm sure it can handle back feeding (without sparks flying, at least).

Click to expand...

yes, ironically the older mechanical meters were unable to detect back feeding from "guerilla" solar installations and so the POCO's updated
their systems. the new digital meter can and will inform the POCO of every Watt back fed and they will come after you with a vengeance if
you do not have a net metering agreement, they have to re-program the meter to measure your generation.

If anything can be said, there seems to be a severe lack of any blog postings or youtube videos sharing the results of using these devices. 
I'm surprised no-one has had experience with one of these in an RV.  It literally looks as simple as plugging the solar grid into these stackable grid tie inverters and then plugging those into a 100v outlet in the RV. 

Click to expand...

I for one would not advertise illegal activity on public media.. yes, they are simple and work but it's only a matter of time before you are detected.
and from the POCO's point of view, you have "stolen" their income as ridiculous as that sounds, they have deep pockets for lawyers and WILL at the very least disconnect you.

BTW, my monthly power bill here in CA is in excess of $200 a month, and I don't even use air conditioning.  So anything I can do to lessen the bill with my own equipment is going to pay for itself faster in this region.

Click to expand...

that seems rather high. I have a 2600 sq ft house in SoTX and with a/c my last bill was $183
may I ask what you pay per kW/hr and where your consumption goes ?

By law, the power companies have to buy your power. That part sounds good.

Unfortunately the wholesale rate you get and the regulations you have to meet can be an issue. That is why many advise being self contained, unless your solar set up results in significant savings.

As always, when you do the math, thing do not always seem so rosy.   

baywardboondocker said:

I'm full time plugged into an RV park's shore power in California.  The prices of electricity keep rising and I'd like to offset the price of electricity from the shore power with an array of solar panels placed on the roof of my 5er, like a grid-tie... skipping the batteries if possible.  My 110v outlets only work on shore power currently.   

I'd like to have power used from solar panels first and then use power from the shore power if the panels aren't enough. I don't want any manual switches or pulling chords, it should be self regulating. Let's keep this thread focused on the how-to rather than numbers.

I did see these units, but I'm not confident in the workmanship: Grid Tie Inverter https://shorturl.at/fLSU9

Click to expand...

You can use a Hybrid inverter charger like the Victron 3000:  https://www.solar-electric.com/victron-energy-multiplus-inverter-12-3000-120.html?gclid=EAIaIQobChMIka-GzNyI3AIVSj0MCh10Ww08EAQYASABEgIb-fD_BwE 

A hybrid inverter can be set to take power from the solar panels and batteries and then from shore power. 

Here is a report from a couple in a RV who uses a hybrid inverter to do something like what you want.  Granted it is not exactly what you are doing, but if you want to take the time to do the research and design a system you may get what you want. 

However when you figure in the cost of all the solar panels, inverters, batteries it will take many years to recoup the initial cost. 

baywardboondocker said:

I'm full time plugged into an RV park's shore power in California.  The prices of electricity keep rising and I'd like to offset the price of electricity from the shore power with an array of solar panels placed on the roof of my 5er, like a grid-tie... skipping the batteries if possible.  My 110v outlets only work on shore power currently.   

I'd like to have power used from solar panels first and then use power from the shore power if the panels aren't enough. I don't want any manual switches or pulling chords, it should be self regulating. Let's keep this thread focused on the how-to rather than numbers.

I did see these units, but I'm not confident in the workmanship: Grid Tie Inverter https://shorturl.at/fLSU9

Click to expand...

There are a number of companies who will install a solar grid tie system for a house.  Probably takes 15-30 years to get your initial investment back though. 

I appreciate the responses.  Essentially, all I want is a big diode on the shore power cord to stop back feeding.  It seems we are over thinking this. I don't want any backfeed into the power company's grid.  I'm surprised something like this doesn't exist.

@AStravelers  thanks for turning me onto the Victron; I'll research that.

@SolarMan I'm in the Bay Area and they do tiered billing and most of my charges fall under the highest tier which is billed at kWh @ $0.27993.    Subsidizing the sanctuary city herion needles program and schooling our new American's from the south isn't cheap! just kidding. kinda sorta.  It's crazy here and I want to get out, but that's another topic.

My electric bill says we used: 603 kWh last month.  That was with no air conditioner and me manually switching off the electric water heater at night.  It may be possible that we have a runaway appliance.. How does that kWh rating look to you guys?  I'm suspicious of the fridge.. it seems to always be one and I have it set at 4 out of 10.

Anything I can do to get this bill down at this point. 

If you're paying 28 cents per KwH, you'll save significant money if you use propane instead of electricity wherever you can.  Switch the water heater and refrigerator to gas instead of electricity.  That's probably 1/2 or more of your total electric bill and may be enough of a reduction to keep you in a lower tier.

The break-even point for determining which energy source is the most cost-effective is about 20:1.  That is, propane is cheaper as long as it's cost per gallon is less than 20 times the cost per KwH of electricity.

BTW, I show your true electric cost as 33 cents per KwH ($200 / 603 KwH = $0.331).  The extra is probably the taxes and fees tacked onto the electric bill.

At 33 cents per KwH, the savings are even more dramatic.  Propane would have to cost $6.60 per gallon to equal the cost of electricity.  I don't know about the Bay Area (I haven't been there for a while) but around here propane is about $3 a gallon.

Of course, this means you'll have to refill the propane tank regularly.  If you replaced 100% of your electric usage with propane, you'll go through about 20 gallons a month.  Eliminate half of your electric usage and you'll use 10 gallons a month of propane.

Switch the refrigerator and water heater to gas, and only turn on the water heater when you need hot water.  If you leave it on all the time it just wastes energy heating water you aren't using.  I turn my water heater about 20 minutes before my morning shower, then turn it off when I'm done.  It stores enough hot water for dish washing, etc. until the next morning.

baywardboondocker said:

I appreciate the responses.  Essentially, all I want is a big diode on the shore power cord to stop back feeding.  It seems we are over thinking this. I don't want any backfeed into the power company's grid.  I'm surprised something like this doesn't exist.

Click to expand...

The problem is you have to use exactly as much power as the solar panels are producing at any given moment unless you have a place to store the excess for later use, either in a battery or by backfeeding it into the grid.  If you use less power than the panels are producing, the excess just goes to waste, i.e. it disappears.

as Lou says.. heat and fridge with propane is your best bet.
average of 33 cents/kW is high

you need to do a power audit and establish what is consuming so much power..

a fridge on 120 V will consume about 300 W so 300 x 24 hrs is 7.2 kW/hrs..
a 1500 W water heater could consume 10 kW/hr a day

you have 600 kW/hrs  per month so that's an ave of 600/30 = 20 kW/hrs per day.
what is using 12.8 kW/hrs in a day assuming your fridge is on 24/7 ?

that's an ave of 533 W per hour..

could you have a bad battery and the converter is charging 24/7 ?

time to start fishing for the power hog..