Grid Tied

[Dave Bond]

Hello ALL. I am new to this web site and new to solar energy. I recently purchased three 12 volt solar panels at 160 watts each that came with cable and a 1000 watt inverter. From what I understood, the inverter plugs into my house AC outlet to provide converted DC energy into AC energy into my house's electrical system. I put my solar panels up on the roof and connected my solar panels in series. Following the instructions I connected the solar panel + and - to the inverter and the inverter to my AC outlet. The inverter showed a fault light. I believe that I purchased a system not mean't to be connected this way? Although it was advertised to work this way. Has anyone out there tried this kind of set up with any success? From what I saw on U tube it is a simple and easy setup, however, I am in Canada and perhaps 12 Volt panels are not compatible with my power company?

Dave

[Joe Blake]

Hi Dave, and welcome to the forum.

I'm not familiar with Canadian law (I'm sure Rob Becker is full bottle on that topic now), but in Australia there is a legal requirement to have an automatic isolation function to disconnect domestic solar from the grid. This has a two-fold purpose. To prevent any worker on the grid from getting a shock, and prevent your panels from trying to power up the whole grid (a big ask), eg when the grid goes down.

In 2006 I started a similar project to yours, and quickly found its limitations. I'd recommend you have the panels feeding into a battery bank (I use Trojan deep cycle 6 volt in series to get 12 volts) and run the inverter from the batteries. 11 years (and a set of batteries) on the system is still going strong, and currently runs two camping freezers, which are switchable from 12/24 volt DC to 240 volt AC. When there's lots of sun I run them at 240 volts which takes them down to -18 deg C, but at night I switch to 12 volts, because staying at 240 would drain too much out of the batteries. They go up to -4 deg C.

I found the system a very useful test bed to experiment with solar power, and I'd suggest you keep going, but add batteries and start out small and work your way up until you reach the practical limits. When you have more experience, this will help you decide what, if any, panels and batteries you'll need to connect to the grid to power up your house. Aside from the initial 12 volt rig, I'm now running 3.2 kW of rooftop grid connected panels with batteries and a "smart" charger to manage the power. After 4 years I still haven't paid for any electricity and am roughly $28 in credit.

Good luck, and keep us informed.

[Dave Bond]

Hi Dave, and welcome to the forum.

I'm not familiar with Canadian law (I'm sure Rob Becker is full bottle on that topic now), but in Australia there is a legal requirement to have an automatic isolation function to disconnect domestic solar from the grid. This has a two-fold purpose. To prevent any worker on the grid from getting a shock, and prevent your panels from trying to power up the whole grid (a big ask), eg when the grid goes down.

In 2006 I started a similar project to yours, and quickly found its limitations. I'd recommend you have the panels feeding into a battery bank (I use Trojan deep cycle 6 volt in series to get 12 volts) and run the inverter from the batteries. 11 years (and a set of batteries) on the system is still going strong, and currently runs two camping freezers, which are switchable from 12/24 volt DC to 240 volt AC. When there's lots of sun I run them at 240 volts which takes them down to -18 deg C, but at night I switch to 12 volts, because staying at 240 would drain too much out of the batteries. They go up to -4 deg C.

I found the system a very useful test bed to experiment with solar power, and I'd suggest you keep going, but add batteries and start out small and work your way up until you reach the practical limits. When you have more experience, this will help you decide what, if any, panels and batteries you'll need to connect to the grid to power up your house. Aside from the initial 12 volt rig, I'm now running 3.2 kW of rooftop grid connected panels with batteries and a "smart" charger to manage the power. After 4 years I still haven't paid for any electricity and am roughly $28 in credit.

Good luck, and keep us informed.

Hello and thank you very much for your reply and information. i find this information very useful and helpful. I will take your advice and begin by buying some batteries.
My solar system consists of three 12 volt 160 watt solar panels connected in series. I surmise this to be 12 volts X 3 = 36 volts DC to my inverter. Do you suggest I buy two 6 volt deep cycle batteries connected in series or one 12 volt battery? Perhaps the Trojan deep cycle batteries? as I understand it, the solar panels connected the controller and then to the batteries and the batteries connect to the inverter and the inverter connects to the appliance I wish to power pending power requirements of the appliance.

Dave

[Joe Blake]

I have 5x12 volt (120 watts each) panels running in parallel. Since the batteries are constantly under load from the freezers I didn't feel it necessary to have a controller. Further, the folding panels I use have a built in controller.

https://www.jaycar.com.au/120w-portable-folding-solar-panel/p/ZM9134

I actually use four Trojan batteries in series/parallel for 12 volts but this set up gives me flexibility as I have two electric vehicles with 24 volt motors and I can if necessary recharge those batteries by reconfiguring the Trojans to suit. When I had my house batteries installed, they were also configured as 24 volts (12x2v) and I had a feed terminal installed as an emergency set up.

You might find this thread useful as it contains a fairly detailed description of my domestic set up, with piccies.

https://www.greenpowertalk.org/showthread.php?t=20783

There isn't very much about my "stand alone" system, but you seem to have the right idea. Solar to controller to battery to inverter to appliance.

[Dave Bond]

I have 5x12 volt (120 watts each) panels running in parallel. Since the batteries are constantly under load from the freezers I didn't feel it necessary to have a controller. Further, the folding panels I use have a built in controller.

https://www.jaycar.com.au/120w-portable-folding-solar-panel/p/ZM9134

I actually use four Trojan batteries in series/parallel for 12 volts but this set up gives me flexibility as I have two electric vehicles with 24 volt motors and I can if necessary recharge those batteries by reconfiguring the Trojans to suit. When I had my house batteries installed, they were also configured as 24 volts (12x2v) and I had a feed terminal installed as an emergency set up.

You might find this thread useful as it contains a fairly detailed description of my domestic set up, with piccies.

https://www.greenpowertalk.org/showthread.php?t=20783

There isn't very much about my "stand alone" system, but you seem to have the right idea. Solar to controller to battery to inverter to appliance.

Thank very much for your information again :)
Perhaps I should consider running my three 12 volt 160 watt solar panels in parallel? Running in series provides higher voltage however running parallel would mean high amps I believe. What do you recommend?

[Joe Blake]

I'd go for parallel.

[Dave Schwartz]

From the wording of the original post, it sounds like Dave has gotten hold of one of those Chinese 'plug-in' grid-tie inverters the are supposed to either help power your household electrics or run your meter backwards.

First of all, there have never been and never will be any of those approved for use. The reason is that you are adding a source downstream of the breaker. Your solar source could be capable of supplying between 3 and 4 amps of current and your breaker is capable of supplying 15 amps (in a 15 amp branch circuit). Now if you plugged in more than 15 amps of load on that circuit, previously your breaker would trip. Now, the circuit will continue to work up to 18 or 19 amps (15 from the breaker, 3 or 4 from the inverter) and some point may see all that current and melt down because its over a component rating.

That breaker is not there to protect your appliances, its there to protect your wiring and therefore your house. If you have a fire as a result, the fire marshal will find it and your insurance company will hang you out to dry.

Secondly, you won't get any credit for the electricity you generate but don't use. Modern digital meters count forward power and reverse power in two separate registers. If you watch them cycle through their routine you will see two separate kWh numbers and unless you have a generation account you get no credit for a reverse power number (and it may even tip off the power company that you have something connected you should not). My load meter has a non-zero number only in the forward power register and my generation meter has a number only in the reverse power register. [Actually, my generation meter says 1 kWh in the forward direction but its been that way since they installed it 6 years ago]

I thought we debunked this years ago.

[Dave Bond]

I'd go for parallel.

OK will do :)