# Untying a Grid Tied Solar system



## NMPRN (Dec 25, 2020)

I've got a 5kW grid tied 'cash cow' sitting on the roof that will be useless when the grid goes down.

I'm looking for a _simple,_ portable and _affordable_ way to be able to use some of the panels for basic needs when the grid goes down. I own the system but if I make ANY changes to it I'd need to renegotiate my contract with the power company, which I really don't want to do. I signed a sweetheart contract back during the obama days and the power company is looking for any excuse to force me into a less lucrative contract.

I'm not sure if I'm on the right track with this plan but I picked up a cheap MC4 connector kit and two spools of 10g wire. My plan is to make up some cables that will connect directly to the panels (bypass the grid tie inverters) and run down to a charge controller and batteries in the garage. I'll run the batteries into an inverter and run extension cords from there to the fridge etc. It won't be very efficient but it'll be simple and affordable. It'll also be portable -enough-. I've left room in the bug out truck for two panels, two batteries and a 20mm ammo can for the charge controller and inverter.

I haven't decided on batteries or a charge controller yet because I haven't decided on what my power requirements really are yet. The only things I NEED to power are the fridge and freezer for a couple of hours each day but I hate to be sitting in the dark wishing I'd built a bigger system.

Besides me not knowing my power requirements (yet), does anyone see any glaring problems with this plan? Anyone have a better idea given what I have to work with?


----------



## Back Pack Hack (Sep 15, 2016)

I'll bet there's language in your contract with the PoCo against doing what you're proposing.


----------



## NMPRN (Dec 25, 2020)

Back Pack Hack said:


> I'll bet there's language in your contract with the PoCo against doing what you're proposing.


I'll bet your right. I wouldn't have to hook it up unless the grid was down, when that happens I don't think they'll be too worried about me though.


----------



## paraquack (Mar 1, 2013)

You need to find out what the voltage of each panel is. When I did research, I found the panels to be used 
on my proposed system would be operating at 400+ volts DC into the grid tie inverter. I doubt you'll ever 
find a solar controller that handles any where near that voltage. So, once you know your individual panel 
output voltage, you need to rewire the panels into a system voltage you can work with. Purchase a solar 
controller of the approoriate voltage, batteries and then an inverter for that battery voltage of the size 
you'd need to operate your house. God luck, you'll need it!


----------



## MountainGirl (Oct 29, 2017)

paraquack said:


> You need to find out what the voltage of each panel is. When I did research, I found the panels to be used
> on my proposed system would be operating at 400+ volts DC into the grid tie inverter. I doubt you'll ever
> find a solar controller that handles any where near that voltage. So, once you know your individual panel
> output voltage, you need to rewire the panels into a system voltage you can work with. Purchase a solar
> ...


God luck is right, lol

It was really interesting to read about your proposed system; I wasn't aware of what the grid-tie setup was like and 400+ volts... that's pretty amazing but not unexpected. As you know, panels put out Watts not Volts, and it's the configuration of the system that governs whether it's whether the voltage is 6, 12, 24, 48... Ours is a 24 volt system; we have 2.5kw up the hill, and ample battery storage. The higher the system's voltage is the more expensive the Inverter is; it was nearly double between the 12 volt and 24 volt inverters... We could have gone with a 48 volt system - but $2,500 for the 24 volt inverter was all I had for that part of the project. Hope you don't have to pay for a 400 volt Inverter lol. You probably won't, they'll supply it for free to keep you tied up.

God luck to you too, & Happy New Year!


----------



## NMPRN (Dec 25, 2020)

My system uses 21 micro-inverters instead of 1 single-point inverter so I don't have any high voltage DC to deal with. 

At most I'd only use 4 of the panels (I can't afford the batteries to make it worthwhile to use mare panels). I'm only looking at 60 volts at 16 amps coming off the roof so a pretty humble MPPT charge controller should work. For what I need it's probably more realistic, and affordable, to only use two of the panels.

My thought is just an easy way to bypass the grid-tied inverters without cutting any cables or making any permanent changes to the system. ...if/when the grid power comes back on I can unplug my cables and plug the panels back into the inverters before the power company gestapo find out.


----------



## Elvis (Jun 22, 2018)

paraquack said:


> You need to find out what the voltage of each panel is. When I did research, I found the panels to be used
> on my proposed system would be operating at 400+ volts DC into the grid tie inverter. I doubt you'll ever
> find a solar controller that handles any where near that voltage.


While both Conext and Magnum both make inverters than can handle up to 600v input and connect it to 12v output I agree that they are too expensive for what @NMPRN is looking to do.

Most grid tie panels run at about 42v and most inexpensive (under $25) controllers can handle at least 100v input so technically you could wire 2 panels in series putting out about 84v and run them through an inexpensive PMW controller. 
But... PMW controllers are very inefficient with any voltage much over the battery's charging voltage. (MPPT controllers are designed to be efficient with high input voltages but expensive.) I'd suggest that the OP wire up to 5 panels in parallel and hook to a 60 amp controller like this $25 controller. https://www.amazon.com/PowMr-60a-Ch...eywords=PMW+controller&qid=1609531014&sr=8-10

By wiring in parallel the input voltage will remain low so the controller will make more efficient use of the available wattage. But by keeping the voltage lower the amperage from the controller to the wiring block will go up. A person can build their own wiring block to connect all of the wires but remember that the wiring block will need to be able to handle 60 amps with 5 large solar panels. This means that the output wire from the block that hooks to the controller needs to be at least 6 gauge and the wire run from the wiring block to the controller be kept short, less than 10'. With larger wire the distance can be increased. This means you'll be running a lot of long 12ga wires from the panels down close to your controller and battery bank.
A wiring block like this one would do the job. https://www.amazon.com/Pair-Termina...609531639&sprefix=wiring+block,aps,184&sr=8-5


----------



## Back Pack Hack (Sep 15, 2016)

Why not just leave the existing system alone and start building your own free-standing system?


----------



## Elvis (Jun 22, 2018)

NMPRN said:


> My system uses 21 micro-inverters instead of 1 single-point inverter so I don't have any high voltage DC to deal with.
> 
> At most I'd only use 4 of the panels (I can't afford the batteries to make it worthwhile to use mare panels). I'm only looking at 60 volts at 16 amps coming off the roof so a pretty humble MPPT charge controller should work. For what I need it's probably more realistic, and affordable, to only use two of the panels..


So you intend to pull the DC wire from the micro inverter and run it to a small controller. That makes sense. I haven't looked at small MPPT controllers in a long time but I can say that the Morningstar MPPT 45 and 60 amp controllers are rock solid and easy to set up. I've had a Morningstar MPPT TS-45 amp running for about 9 years in my shop with no problems. The controller is limited in it's programmability but that keeps it simple to work with, especially when using AGM batteries so you aren't checking your SG levels anyway.

For batteries that won't be used except in an emergency I'd get AGM batteries and keep them hooked to a battery tender.


----------



## stowlin (Apr 25, 2016)

First please don’t try anything before SHTF leave as is and that includes for normal power outages. When they grid tie them it’s for their safety more than anything and if you change that you run the risk of injuring those who are expecting the grid to be off and not receiving power. 

Now that said what you need is an inverted and battery array to take advantage of the panels in a crisis. When that time comes there is no power company you need the power from those panels not the grid. You’ll want to learn how to disconnect theirs and connect it to your battery array and that to your power outlets.

When these leased and grid tied systems started someone offered up a quick switch that made it super easy, and they killed a linemen in CA and injured another during a power outage when they flipped said switch so they could watch MLB games. There was an ugly story about it 7-8 years ago,


----------



## NMPRN (Dec 25, 2020)

I did a bad job of explaining what I'm doing. I'm not doing anything out of the ordinary when it comes to hooking panels to a charge controller. The only thing I'm doing that's noteworthy on a prepper forum is trying to build a cheap, portable 'kit' that let's me use otherwise useless panels on a grid-tied system when the grid goes down. 

There are going to be lots of people sitting in the dark while lots of solar panels go to waste when the grid goes down because they don't have a few hundred dollars worth of equipment stuffed in a 20mm ammo can. If I can talk my neighbors into doing the same thing I won't have to share my power with them 


EDIT: just to clarify
When the grid goes down I'm going to climb on the roof and disconnect a few panels from their inverters (simple, safe, MC4 connectors. it's a safe as unplugging a lamp from the wall. that will disconnect them from the grid also). Then plug a cable into the panels themselves (each panel is about 37 volts DC at 8 amps). The cable(s) will run off the roof down to a charge controller. When the grid comes back up, I just unplug the charge controller cable from the panels and plug the panels back into their inverters. 

The only dangerous part is climbing the ladder


----------



## Back Pack Hack (Sep 15, 2016)

How can panels that are installed on your roof be 'portable'? Or are you just wanting to charge a portable _generator _and use said generator to create your own power?


----------



## NMPRN (Dec 25, 2020)

Grid tied inverters need to see a steady pure sine wave (grid power) for several minutes before they allow solar power back on to the grid. That keeps errant spikes on the line from accidentally turning the inverters back on and frying a lineman. Every part of the system that meets code (switches, batteries, inverters, etc.) won't allow power back on the grid if the grid is down.

The cables I'm talking about can't physically be plugged into the panels until the panels are physically unplugged from the system. When the grid power comes back on my system would just report that 4 panels wern't working. If something like an earthquake brought the grid down I woldn't want to be connected to it anyway, same for the wiring in my house if the house was damaged. 

Theoretically you could just pull the main breaker on your house and use a battery and a pure sine wave inverter to trick the micro-inverters into coming back on. You'd have full single phase 240 volt AC while the sun was shining, more than enough power to use a regular battery to charge the batteries and run just about anything short of an arc welder. ...but that's a bad idea for a lot of reasons 

re: leased systems
I don't know of any leased systems in my area, they're all privately owned. The contract I signed was for an incentive program where the power company pays me for the power I produce and then lets me use it for free. That's why (around here anyway) we call solar systems "cash cows". Nobody gives a poop about saving the planet, we just want the check every month


----------



## NMPRN (Dec 25, 2020)

Back Pack Hack said:


> How can panels that are installed on your roof be 'portable'? ...


They're only held to the racks with a few bolts. It'd only take a minute to take one down.


----------



## Elvis (Jun 22, 2018)

Just a thought... Most MC4 plugs can be a very difficult to unplug without damaging the "hooks" without the proper tool.


----------



## Elvis (Jun 22, 2018)

NMPRN said:


> They're only held to the racks with a few bolts. It'd only take a minute to take one down.


Agreed, and if you pull the panels at the start of the string and unhook their micro-inverters your system will still work but with a bit less output.


----------



## NMPRN (Dec 25, 2020)

Elvis said:


> Just a thought... Most MC4 plugs can be a very difficult to unplug without damaging the "hooks" without the proper tool.


The little kit I got on amazon has a couple of the tools in it. I'm not real thrilled with the quality but I was thrilled by the price. I'll also need a bunch of different connectors (branch connectors etc.)


----------



## Elvis (Jun 22, 2018)

NMPRN said:


> The little kit I got on amazon has a couple of the tools in it. I'm not real thrilled with the quality but I was thrilled by the price. I'll also need a bunch of different connectors (branch connectors etc.)
> 
> View attachment 110413


Yea, branch connectors are expensive. About $10 each as I recall.
On my older shop system I used branch connectors when I doubled the panels so I could still use the Tristar controller. Later on the house system I popped for the more expensive Conext high voltage controller.


----------



## Weldman (Nov 7, 2020)

NMPRN said:


> The little kit I got on amazon has a couple of the tools in it. I'm not real thrilled with the quality but I was thrilled by the price. I'll also need a bunch of different connectors (branch connectors etc.)
> 
> View attachment 110413


Renogy is the place to go for MC4 connectors and such you seek, you can also put some 8 gauge wire instead of 10 for longer running distances. I have 1800 watts on my RV rig that are portable with such setup and can go 50' from the source.


----------



## Trihonda (Aug 24, 2020)

I have been really diving into the solar space. We almost pulled the trigger on a $30K roof (grid-tied) system. But we decided against at the last second. I snagged a small 300W solar generator (and two portable 100w folding panels) for small personal electronics (comms, lights, etc..). But I want something bigger. I've really been eyeing up this Inergy Flex for a few months now, but it's pricey, AND it isn't slated to ship out until Feb (possibly). There are even talks of a Inergy 3000w system in the near future, that is backwards compatible with the batteries.

I have also been in talks with the wife about a small lake cabin or off-grid vacation home My goal would be to attempt to get close to 100% solar power, AND all wood heated. Not sure how viable this would be. I might need grid tied, but Im not sure. I was also wondering the feasibility of using the amazing Inergy battery system, in conjunction with the main power unit, to provide some sort of backup power, or partial power to a number of the cabin's electrical needs.

When we were going to get a grid tied solar unit on our roof, the couple companies we looked at both told us it's feasible to have a battery system, but the batteries tend to cost $8-10k for enough to be useful. Figured the Inergy batteries might be a game changer?


----------



## Elvis (Jun 22, 2018)

First understand that my solar system was not designed to be totally off grid. Instead it was designed to sell excess power back to the grid with a small battery backup ($2400) for power outages which happens several times a year here. But the local power company seriously reduced how much they were paying for power I made so we are now mostly off grid which means a much larger (and more expensive) battery bank.

While we already had put some effort to becoming more energy efficient we really got serious about it when we moved to being mostly offgrid including switching to propane for the stove, some house heating, and hot water. By mostly off grid I mean the inverter monitors the incoming grid but doesn't pull power from the grid unless the batteries get low. To avoid power company line service charges we must use some electricity so the clothes dryer in on a circuit that is grid fed. Our power bill runs about $22 most months but if it rains for several days in the winter the batteries will get low and the inverter will pull some power off the grid automatically and we'll get a $45 power bill that month.

The trick is to get more energy efficient. The 1st year I lived here using a lot of wood heat and central AC we averaged 1150 kwhs a month. We now average about 680 kwhs a month total electrical usage including the clothes dryer, mini-split AC and heating. well pump, and all other electrical needs. Part of the savings was from moving to propane cooking and water heating. Part of the savings was from more efficient appliances like going to a 22 seer mini-split with heads in several rooms.

There is no reason why a person couldn't get by with a smaller battery bank being grid tied. The inverter would simply pull power off the grid more often but you'd still have battery power for emergencies. @Trihonda


----------



## NMPRN (Dec 25, 2020)

Trihonda,

That's a nice battery system but for the cost I wonder if you could build your own that has twice the capacity.

I sized my PV system to be "net zero" +% 50 so it would have positive cash flow all year. I have an incentive to save energy _now_ (bigger check) but when my contract expires in a few years the opposite will be true. All my excess production will go back into the grid and I won't get a dime for it.

I'd like to isolate my living room circuit and run it completely off batteries that would be charged with the excess. The loads are pretty low (the TV and a few lights), I could run it off a pretty humble battery bank.


----------

