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How can I intergrate microinverter grid tied system into off grid system?

mfred68

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Aug 17, 2022
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Im wanting to go off grid (due to massive energy hikes) but i already have a grid tied 3kw system installed that pays me a feed in tariff and generation tariff, which I don't want to jeopardize.
My plan is to install another 12 to 15kw pv system on my space and have a 20 to 30kw of battery storrage. ( so it works well in winter months too)

Can anyone please tell me if there is a way of integrating my existing grid tied micro inverter system into the new off grid system, so its used only to charge the batteries without using grid energy to charge the batteries when theres not enough solar?

I currently have an Iboost immersion heater solar diverter controller, which only uses solar to heat the water due to a current sensor on the grid meter wire, so is there somthing similar available to charge a batteriy bank instead of an immersion?
 
That depends on where you are and what your power requirements are.
240v/ 120v split-phase
230v single phase
XXXv 3 phase
 
Actually the short answer is that you need a hybrid AIO with grid tied and AC coupling capabilities.
 
i'm in the UK and use on avaragw 20kwh a day.
Can you suggest a suitable AIO?
 
Does your electric utility (power company) limit the size of your array? Where I live they do if you sign up for “Net Metering” where you sell back.
 
yes they do limit it to 4kw, but for off grid we can go as big as we want, so I want to go off grid, but still keep my existing array grid tied mainly because I get paid several hundreds pounds each year for production
 
Idk about very many inverters, but a Sol-Ark (Or Deye in your country) you can connect AC and DC Coupled panels simultaneously, and then limit the Sell-Back to the exact amount the power company requires you stay under, so you can tell the Sol-Ark (Deye) to only feed back up to 4kw, and the rest will either go to batteries or loads.

Why don't you just leave the grid tied in place and run a completely separate Off-Grid system? No need to intertwine them.
 
It's easy. Setup your essential loads sub-panel, powered by an off-grid all-in-one inverter/charger like the MPP, and plug it in, or hard wire it to your panel. It has the ability to charge from the grid, and your existing PV array will offset the energy you pull from the grid. Just program it to only charge during the day. You may require a timer relay on the input, but that's about it. You can add more solar panels directly to the off-grid all-in-one inverter.
 
My existing system is indeed Enphase but I can get cheaper higher kw batteries from Ali
Programming an inverter/charger to charge from my micro inverter panels during the day, runs a big risk of pulling power from the grid instead of the panels, because we are very unfortunate to have more clowdy overcast days than sunny days here in Wales, this I why I want an over sized new PV system to compensate for the lack of sun here.
Installing an AIO hybrid inverter, makes me concerned of red tape, with approvals and jeapodizing my current generation payments.

Ideally I want a controller that is similar to an eddi, for my AC array, but instead of heating water, it charges the batteries, (while keeping the new off grid system totally off grid) do they exist?
 
No. There is no way to A/B switch the solar panels from Enphase Microinverters to a PV Charge Controller to charge the batteries. For one, they would need to go from a configuration of 1 panel to 1 inverter, to several panels in series to connect the string to the charge controller. It's just not practical. If you don't want to ever charge from the grid, you need a separate AIO inverter with its own solar panels.
 
i'm in the UK and use on avaragw 20kwh a day.
Can you suggest a suitable AIO?
Deye is what you want.
It will allow you to keep your existing contract with the utility company and add batteries and more solar. Even a generator if desired.
 
Hello, this is how I fix my situation, the Enphase IQ system (6 years old) I own does not have battery backup, (and is able to use their batteries) but for a great cost IMO so not worth for me to go that route. I designed an off grid battery backup system, it has a Growatt, 3k, 48v and 12Kw of battery capacity. When the power goes out, the main Enphase PV system shuts down. I then fire up the Growatt and feed the house with it, the only thing that I can't run is the 3 Tons central AC unit, but it can run 2 mini split units one on each floor. For the lights and small appliances, I use another smaller battery backup system (5Kw). Since the power outages here in TX have not gotten to the point where the main PV system is worthless, meaning that while the grid is up they can operate just fine, I don't really need a full time backup system, but just for emergencies and to supplement the main PV system, I use the 12Kw system to run the split units and to reduce the main AC unit from running all day during hot summers. My bill this month was for 6 USD, and that is about the average monthly, depends on weather, sometimes if is cloudy it might go up but not by much and can never exceed 32 USD for the next 2 decades or so, and it have never come close to that. My bills during the summers were around 160 USD. In the event that the grid goes out and stays down for extended amount of time, I have the option to bypass the micro inverters off the main PV system and use them for 100% off grid power requirements daily. Not the most attractive solution and requires some configuration changes but it works for me, and during 105f weather is a must to have something and the best part is that I was able to afford it! Enphase wanted 20k to add batteries to my main system!
 
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