Grid-Tie, Cheap and simple

[Supervstech]

Grid tie micro Inverters are rated at what they will output.

If you hook 10,000 amps of solar panels in parallel all below the maximum input voltage of the inverter, the inverter will only use 220 watts, or 15 amps... whatever input is rated to stop drawing at...

 

[TheDroidsYouAreLookingFor]

awesome! thank you for the info! I feel like I knew that at one point because I was thinking of using a battery to power an inverter at night. Don't know why 2 and 2 didnt click but it makes super sense now! THANK YOU

 

[DThames]

"Ever wonder why 12/24v charge controllers can handle 800 watts at 24 volts but only 400 watts at 12 volts." I think the real answer to this (not related to the panels) is that there is a lot more heat trying to regulate 36v down to 12v than trying to regulate 18v down to 12v.

 

[DThames]

Grid tie micro Inverters are rated at what they will output.

If you hook 10,000 amps of solar panels in parallel all below the maximum input voltage of the inverter, the inverter will only use 220 watts, or 15 amps... whatever input is rated to stop drawing at...

Right. I was thinking (while working) about this after reading the updates on this thread at lunch.

Suppose the inverter wants to max out and produce 220watts of power on a 230v grid. The grid voltage is actually 243volts. The heating will be related to (I^2)*R. To get 220watts out at 243volts, the amps don't need to be as high as for 230v, so the heating is a bit less and if so designed, the inverter might do more than 220w and be happy as can be. On the input side, say you have the option of two 120watt panels or three 100 watt panels, with the cells in the panels being the same, so apples and apples. The open circuit volts of both the 100watt and the 120watt panel are the same. When the inverter takes 220watts plus loses from the panels, it will load them to get that power. The three 100 watt panels will be "stiffer" and resist voltage sage better than the two 120 watt panels, so the amps again will be lower, less heating. Better still is the fact that someone will get their 220watts for more minutes of the day with being larger than needed. Of course real estate,, mounting costs, and panel costs all have to be considered.

 

[Supervstech]

Ideally, you want the voltage as close to the maximum the microinverters can handle.
Higher voltage is easier to convert to line voltage.

 

[DThames]

Ideally, you want the voltage as close to the maximum the microinverters can handle.
Higher voltage is easier to convert to line voltage.

Because they were cheap, I have panels with 83 cells, which work with the inverters meant for 72 cell panels

 

[TheDroidsYouAreLookingFor]

Hey guys, quick update. Got mc4 connectors to replace the old "mc" type connectors. Im using the renogy connectors that are a tad more expensive but work well amd seem to be high quality. 6 more inverters also came in the mail today bringing me to a total inverter wattage of around 1.5kw. Still waiting on breaker, throw switch and a few odds and ends before assembly. I ran the single inverter for 4 days and made 4.5 kwh just leaning against the garage nearly vertical.

 

[DThames]

What inverters are you using?

 

[TheDroidsYouAreLookingFor]

Im using new inverters from a company that went out of business. I dont really want to give away the brand at the moment because id hate for them to go out of stock. As soon as they're gone they're gone and im buying them as i can afford them at very low cost vs. New.

 

[kernel]

Those Shell Solar modules are the best of the best. They will likely last 75 years.

Better than gold!

 

[Supervstech]

Those Shell Solar modules are the best of the best. They will likely last 75 years.

Better than gold!

I think gold is better...

 

[kernel]

Not in my case. It cannot be eaten, smoked or built with, makes terrible machine screw hardware and does not keep the woodpile dry!

Ill take the steady flow of electrons for life and then leave it to some younger people.

 

[TheDroidsYouAreLookingFor]

I agree these shell modules seem to be about 10 lbs heavier and the silicon is much thicker wafers, noticeably so when comparing the 2.

 

[TheDroidsYouAreLookingFor]

A quick update. Had some time yesterday and today to work on my pipe racking. Its not great but it should do. Old well pipe a few pieces didn't hold pressure anymore but still works great for structure. I've decided to set this whole structure on the roof of my garage. Before anyone gets carried away with solar angles and calculations, plainly I don't really care they are pointing south and will get enough sun. I will have 2x180w panels per 220w inverter, one 220w inverter with 3x140w panels and 3 more 220w inverters with 2x140w panels. It's what I have and what I'm using. The panels are used and possibly degraded so hopefully each inverter can realize its 220w potential. Some previews of ground assembly.

 

[TheDroidsYouAreLookingFor]

Hey guys, I know that I don't post often on the forum but I lurk and PM often. I have still been making progress one hour at a time and thought I would show how far I have come. I know that I am not a professional by any means but its up and working. As of right now I have 8 panels on the top of the garage. Each panel is 140 watts and 2 panels feed each 220 watt inverter. They are UL listed string inverters and continue to a Disconnect switch and then to a 15 amp breaker as the manufacturer required. I finally threw the switch yesterday and started making power again. Its cloudy but still producing, waiting for the sun to pop out but excited. Feedback is appreciated, this is a work in progress and I aim to make everything safer and overall better as I go along. As I stated before, this is more of a demo system for me and is intended to make "some power" while learning stuff. Its on my detached garage so I don't have to worry about burning down my house trying to be a mad scientist. The yellower cable that's all floppy is the one I threw in there.

 

[TheDroidsYouAreLookingFor]

The inverter is micro replus. Sold on amazon $60ish Its a closeout deal by discount jungle. I'm done buying them as I have what I need. If anyone help with them I can talk you through it. 220 watts out 22v-55v in. Mppt, rapid shut down, ul listed, all that jazz...

 

[TheDroidsYouAreLookingFor]

The inverters are attached to each pair of panels. They are string inverters so they plug into each other to make a line. I just ran 12/2 romex with ground from the 15amp 220v breaker I added. From the breaker I ran the wire to an outdoor rated disconnect. Next I ran it to a box behind the wall and wired in the first inverter directly. I'm adding a little at a time but I'm 880watts of inverter with 1120w of solar over paneled. More detail in previous posts. Still adding more.

 

[TheDroidsYouAreLookingFor]

Well, as of today the rest of my inverters and panels are installed. I had to wait for a break in the rain. It should be raining for another week or so. I average about 25% of production capacity when it's raining which is better than I expected. Other people have seen my system and love that it costs so little. Total cost is under $1200 for 1500watt of inverter connected to 2500 watts of panel. I figure free air conditioning during sunlight hours will be really nice in summer. consumed by household loads. Its ugly but pictures to follow.

 

[ComeToTheLightSide]

Nice system.

 

[sed6]

To be fair My quored price was for someone else installing everything. In my state and county permitting is expensive, and everything is highly regulated. (Even solar racking has to be specifically approved) i priced just getting the smallest system then adding on with my own and it was still quite a lot. $1500-$3000 is just the electrical engineering of the system. Even then i wouldnt be allowed to use my panels because they are "old" and not on the ever evolving list of new stuff thats allowed. I want my system to be safe i just dont want to line someone elses pockets to make my own power. Even the connection agreement requires money that would cost more than my entire system.

I have seen the sun grid tie systemscand have thought of using a current limiting system. If i go that route i will use frontius or victron units that are ul listed and known for quality and longevity. The new ESS Victon self consuming systems being my favorite using a multiplus II with current sensor. Up to 5,000 watts, phase balancing, time shifting ect. Its a programmable power wall that works on or off grid.

Also i eventually plan to sell my house and move, somewhere for the same reasons Will did in his videos. I may or may not pull the trigger on my new home for grid tied solar. For now price per watt i think minimalist setup is the best bet.

I really agree with everything you said. The stiff permitting here also leaves me going your route. I went with the MPP LV2424 Hybrid inverter myself, here is my DIY Tesla Powerwall thread if you're interested to see the route I'm going.