Help me move into my new home

[mountkay]

Hello!

(Mods feel free to move this to a different thread category if it seems like it belongs somewhere else).

I am moving into a new home on my property finally after living off-grid on the property in a camper for 8 years.



I’m keeping my new home off-grid.

I had a solar engineer help me with plans for the wiring and ground mounted panels so I can make sure I pass inspection.

I got the ground mounted system all set up with the help of friends and family.


6.8KW (20x 340w Seraphim Panels). Iron Ridge racking.

I purchased a 6.5KW EG4 inverter, and (2x) 5KW 48v EG4 batteries.

I was planning on keeping my system at 120v.

Unfortunately I decided to go with a 240v well pump; I figured I could use a transformer or voltage converter for just that one appliance and I would be fine.

But… I just found out my water heater is also 240v… and it uses 3-4KW. They told me it was 120v (I got a manufactured home)… so it seems using a transformer is no longer a feasible idea.

Rather than spend time and money changing to a propane heater and still getting a transformer for the well pump, I think I would rather get another 6.5KW EG4 inverter so I can just make 240v split phase.

What do you think?

Here is the wiring diagram I received from the solar engineer:

(It’s for the 120v system I originally planned on doing)

Sorry, it’s split into multiple pictures so it shows up clearer.



Can you spot any mistakes?

My next questions to him will be about the ground wire coming from the panels into the house to the inverter… I don’t know where I would attach it to the inverter.

Also I don’t understand where I would run a ground wire from the inverter to the battery bank.

Also he has me putting 2 strings of panels into parallel. But, the panels are 9.02 ImpA and the inverter says it can only handle 18 ImpA… (so it would go over current at full sun? Maybe he just expects this never to happen as it’s rare the panels will be at full strength?)


So I decided to draw up my own wire diagram based on what it might look like as a 240v system with a second 6.5KW inverter.



How does it look?

I just brought the ground from the solar panel rack past the inverter and straight to the sub panel.

No ground going to the batteries…

And rather than put 2 stings of panels in parallel I just put one PV string to the 2nd inverter (it would still be good to know if (2x) 9.02 ImpA stings in parallel would be okay for this inverter rated at 18 ImpA).

Also, I know in Wills video on this 240v system he has the grounds and neutrals on the same bus bar in the sub panel. I didn’t do it this way because idk if it will pass inspection, or if separate bars are required if I have the generator hooked in there.

I didn’t put the generator backup in, as I’m not sure how it would work because it only makes 120v. I believe in the original 120v plan he has it connected to a muli-tap connector so it split and could power the house directly, or power the inverter.

I’m guessing if I switch to 240v I can no longer have it connected to the sub panel… and will have to connect it directly to an input on one of the inverters…

Will it work putting a 120v input to an inverter if it’s set up to output 240v?

This would allow me to charge the batteries if there’s not enough sunlight, but it wouldn’t help me if one the inverters broke….

It would probably be better to have it wired into the sub panel AND inverter if that’s possible.

Also, does anyone know a good replacement for the battery bus bars? Wills recommended link is out of stock. (I’ll try to search this in the forums, I cant be the first to have asked).

<3 Anyway if you’ve read this far, I hope you enjoyed my story. I’ve been a huge fan of Will for many years, I don’t know why I didn’t join here sooner. He is very inspiring (Thanks Will!) And thank you for any responses. It’s much appreciated. I can’t wait to live in a house again after roughing it for so many years.

Since you made it this far, here’s a bonus picture of me and my buddies 3rd year off-grid small scale farm (solar panels on the roof of the small shed there + LFP in the shed for watering, separate solar well pump system not pictured).

 

[Hedges]

Connect your water heater to 120V, and it will use 1/4 the power, take 4x as long.
(assuming that is a resistance heater, not heat-pump)

Some inverters will take single phase input and create the missing phases. If they can't synchronize and add their own amps to the input AC amps, only switch between AC input and inverter, they're not going to be able to do that. Have to read the manual, and try it.

If your generator has ungrounded neutral, then grounding neutral at breaker panel would be the thing to do. Separate busbars and a screw to join them is good.

I think code calls for grounding 48V batteries. But make sure that isn't a problem for the equipment.

It take a lot of solar to power electric heating (and pumping). But total power consumed by water heater may not be that much, depends on usage. Winter, sometimes not much sun. All you can do is estimate production/consumption, and have backup generator.

Well pump takes starting surge, typically 5x running. Inverter has to supply that, as do batteries.

Do you have a precharge circuit, or are the battery & inverter supposed to start up together fine, already have something built in?

 

[brum]

I would keep the 240V water heater and run it at 120V. More time to heat up the water, but with lower losses due to the lower current. This will improve the overall system efficiency.

I was using solar power for a while to heat up the water heater. It had 3x3kW heating elements. The wiring was modified so I run 2 or 3 of them in series. Two in a series result in 1.5kW power, and 3 in a series - 1kW power. This allowed me to spread the load over a larger time window and maximize sun consumption (grid-tie system, no batteries).

 

[peakbagger]

FWIW, if you are in upper state NY and depending on your ground mount panels, get the lower edge much high off the ground and at a steeper angle of tilt. Snow landing on the panels will slide down and form a frozen lump covering the lower edge of the lower panels. The lump sill be higher than the surrounding snow. Steeper angle panels in winter means more output due to better angle with the sun and more importantly better reflection off the snow.

I have an adjustable pole mounted array I built years ago for smaller panels. I got a deal on larger panels and rebuilt the array for the larger panels and the trade off is the lower edge is about 2 feet off the ground with the array at 30 degrees. I have to run my snow blower in front of the array to keep the "lump" from covering the lower edge of my panels.

WIth respect to the well pump, if its standard multistage centrifugal deep well pump, you may be able to convert it to variable speed drive if you have an external capacitor (the capacitor is up above ground rather than built into the pump. That cuts the startup surge of the pump to zero (and extends pump life). Franklin Electric sells a conversion device called a "monodrive".

With respect to hot water, there reportedly are heat pump hot water heaters being built for 120 volts. I dont need one so havent taken the time to search for them. The draw about 1/3rd the power as resistance type heater and you may be able to get an incentive to install one.

 

[rancher1913]

switch out the water heater to propane, it will pay for itself quick considering the cost of the 240 system as well as the constant drain on the solar system. switch out the well to a dc pump to a surface tank and then install a dc pressure pump to supply house.

 

[Hedges]

Propane takes load off the electrical system, but is a cost and can run out.
Do you have surplus power from PV, after batteries full? If so, water heater can be your dump load.

I've read mixed things about soft-starting deep well pumps.
Grundfos sells them, including PV direct. Some people had failures, which installer blamed on grit.
But another poster said deep well pumps run on a water bearing, and slow start increases wear vs. slamming to full speed as an induction motor getting line voltage & frequency.

If you can start the pump by inverter, I think you're better off having a large above-ground tank and running the pump for an extended time while getting full sun. If there is another large load like water heater, wire the pump switch to open a load-shed relay disconnecting the other load.

At $1300 for the inverter, yeah, buy two.
120V output, so if you wire your place for 120/240V, consider doing it so you can connect 120V to both phases if one inverter is out of service. (make sure neutral current is OK, don't share one neutral between L1 and L2 for two branch circuits.)

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[mountkay]

Connect your water heater to 120V

I would keep the 240V water heater and run it at 120V.

Thanks for the recommendations on this. I will see if I can wire it for 120v. Can you do this with any water heater? I see the manual has a diagram for 120v, but I thought it was just to encompass all of their models. I will definitely wire for 120v if possible.

Some inverters will take single phase input and create the missing phases

I’ll look around to see if this is possible for my inverter. Thanks!

I think code calls for grounding 48V batteries

I see the manual for the battery talks about grounding them. I’m not sure how that will work, but I’ll make sure to do it.

Well pump takes starting surge, typically 5x running. Inverter has to supply that, as do batteries

you may be able to convert it to variable speed drive if you have an external capacitor

I've read mixed things about soft-starting deep well pumps.

Here are the well pump specs. LRA is “locked rotor amperage” that’s the starting amps. 230v x 18a is 4140w.
I don’t have a pre charge circuit. It looks like they cost more than another inverter will cost. And with a 2nd inverter I will have 26KW surge wattage. Plenty for the pump and water heater.

switch out the water heater to propane, it will pay for itself quick considering the cost of the 240 system

Propane takes load off the electrical system, but is a cost and can run out.

If I was to switch to a propane heater I would probably want an on demand one. Seems like they are $900. And then I have to do the install, make holes in the house for venting.
I’m good at living with the cycles of the sun so I think I will be good to shower and do laundry when the sun is shining and be ok with the electric heater.

switch out the well to a dc pump to a surface tank and then install a dc pressure pump to supply house.

I think you're better off having a large above-ground tank

I think for the price of a tank and the work to dig the hole and installation, I would just be better off getting another inverter.
I’m on top of a hill so there’s rock like 4ft down. And with freezing weather I would definitely have to bury an external tank.

Snow landing on the panels will slide down and form a frozen lump

array at 30 degrees

I will definitely have to worry about this. The array is already finished though. So I can’t change it.
I made a line graph using PVWatts calculator and decided 55deg would be best for me. Only problem is this ground mount racking (IronRidge) can only go to 45deg. And at 45deg I need 2x as much poles and concrete as 40deg, increasing the cost greatly. I had no idea how much the ground mounting would cost. In total it was probably $5k. More than what I paid for the panels ($3k). I went with 40deg for my array.

KW/month/ degree of array


Total KW/ year / degree of array


Thanks for the information and suggestions everyone!!!!

 

[iwasforcedtopickausername]

You can easily change out the heating elements in most hot water heaters. As has been said, running 120V to it is probably just fine. But if you want to be more efficient, you could have a few panels dedicated to running the hot water heater directly, bypassing batteries and all. May or may not give you enough hot water, but does lower current needs considerably.

I do recommend propane if it's an option. You could plumb it so you can use electric or propane, switching over a couple valves to one or the other.

You're probably going to have a tough time with snow. That array is not very high off the ground. At 40 degrees, snow shedding may be tricky at times, but I get that mounting the panels is a pain. You'll have great output whenever there's no snow.

 

[brum]

Thanks for the recommendations on this. I will see if I can wire it for 120v. Can you do this with any water heater? I see the manual has a diagram for 120v, but I thought it was just to encompass all of their models. I will definitely wire for 120v if possible.

In most cases - yes. The only case when this may not work is if you have a water heater with digital control (microprocessor, display).

For a plain old mechanical water heater (with bimetal thermostat) you can plug any 240V AC heater directly at 120V AC. The downside is that heating power will drop 4 times, but this in some cases is an advantage. Photovoltaics is one of the cases.

If solar power is not enough I would consider an LNG or LPG water heater. A month ago we were installing a heat pump and we were left without hot water for a few days. With 3 kids! The old camping LPG water heater saved the day .

 

[Nobodybusiness]

Connect your water heater to 120V, and it will use 1/4 the power, take 4x as long.
(assuming that is a resistance heater, not heat-pump)

Some inverters will take single phase input and create the missing phases. If they can't synchronize and add their own amps to the input AC amps, only switch between AC input and inverter, they're not going to be able to do that. Have to read the manual, and try it.

If your generator has ungrounded neutral, then grounding neutral at breaker panel would be the thing to do. Separate busbars and a screw to join them is good.

I think code calls for grounding 48V batteries. But make sure that isn't a problem for the equipment.

It take a lot of solar to power electric heating (and pumping). But total power consumed by water heater may not be that much, depends on usage. Winter, sometimes not much sun. All you can do is estimate production/consumption, and have backup generator.

Well pump takes starting surge, typically 5x running. Inverter has to supply that, as do batteries.

Do you have a precharge circuit, or are the battery & inverter supposed to start up together fine, already have something built in?

No kidding? I wasn’t aware of that.

Do you know specifically which inverters will take 120 and produce missing phase?

 

[Hedges]

Many inverters have a transfer switch, either inverter from battery or pass through from grid, but not both.
Obviously, even if a stacked pair of 120V inverters, those won't pass through one 120V phase and make the second phase (might be possible if they designed for that purpose, but not aware of any.)

Sunny Island (as in my Avatar) does do it. These are grid-interactive inverters, able to take AC from the grid and add power inverting from battery, for instance to limit input current to 10A or so while providing 50A on the output.

Possibly other stackable 120V grid-interactive inverters can do this, Outback for instance.

With multiple inverters connected for 120/240V split-phase or 120/208Y 3-phase, when grid AC is present for master, it will synchronize and connect. If the slaves don't also see correct voltage and frequency, they don't connect, rather continue making AC at 180 degrees (or 120 & 240) relative to what master sees.

I have a 3-phase setup as well, with one phase of grid connected. When PV into Sunny TriPower delivers balanced 3-phase power to Sunny Island, two inverters suck that down to battery and one inverter takes it off battery, adds to the first phase, backfeeding grid. When grid is disconnected the three operate as an off-grid system. (Power handling is limited to 56A x 120V = 6.7kW on-grid. If I get curtailment working, should be able to export-limit to that figure. For now that is the PV limit.)

3-Phase SMA Sunny Island (15kW) + Sunny TriPower (30kW)

Showing a work-in-progress assembling 3-phase SMA system. 3x SI-5048-US are configured for 3-phase and produce 120/208Y, rated 15 kW continuous. Sunny TriPower 30000TL-US-10 is 480V delta (or 277/480Y), rated 30 kW. TriPower combiner box will be used, but for now just one string being connected...

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