Inverter sizing

[wingshadow]

Let's start simple. I'm a farmer with some mechanical/electrical skills. I'm going to install my own system from scratch. I've got 40 panels at 250w and 30v and a controller that I'm told will need 192 dc input. I need to hook up an inverter to carry the load and give me max power. I want 220vac and 110. A full house and farm set up. First) can I plug my inverter into the circuit panel box that my old electric power was hooked to ...and split the 220 input just as if I were hooked to the grid?

[Sunking]

So no problem right?Sure you can, just one little catch. You need a 5000 pound, $17,000 dollar battery you get to replace every few years. One more little catch you should have no problem with money bags. Instead of paying that mean ole greedy power company 10 to 15-cents per Kwh, you get to pay your friendly battery dealer $0.50 to $1 per Kwh the rest of your life. Well actually each replacement cycle goes up.

So no problem you can do it money bags. Don't kid yourself, it will never happen.

[wingshadow]

I guess that is a no... and I pay .41 per Kwh. Is there a way around the battery problem? or am I asking for too much from a 40 panel system? Must be some way to make this work. Do I need multiple setups? A couple inverters working separately?

[J.P.M.]

I guess that is a no... and I pay .41 per Kwh. Is there a way around the battery problem? or am I asking for too much from a 40 panel system? Must be some way to make this work. Do I need multiple setups? A couple inverters working separately?

Is that $ 0.41/kWh the rate for every kWh, or are you on a tiered tariff, demand rate or some such arrangement with that being a max. rate ? Or, are you off grid completely ? Seems kind of high as a POCO rate unless you're in HI or have some unusual circumstances, or already generate your own power.

[sensij]

Profile location says southern CA. Just pull the permits, file the application with SCE or SDG&E or whoever, and make it a grid-tied system. Get help with the plans if needed.

What kind of "controller" do you have? Probably plan to sell that on Ebay.

[Mike90250]

I woudl look at getting a Grid Tie inverter that takes high voltage DC from the panels (all wired in series) and puts it onto the AC feed - making the meter unwind !! But you have to have a sell back agreement with your local power co, and inspections to make sure the thing is all safe and such.
But putting those panels into Grid Tie use would be the thing to do.

[wingshadow]

I realize i can grid tie... That is not what I wish to do. That is why I have the panels, to be free of the electrical grid. Can I do this by using multiple inverters? I know my basic problem is storage. My sunlight is good and I only need minimum storage if I have a way to use the power during the day and use a minimal at night. Are you telling me solar is not the path to get off the grid? Any help is appreciated.

[J.P.M.]

I realize i can grid tie... That is not what I wish to do. That is why I have the panels, to be free of the electrical grid. Can I do this by using multiple inverters? I know my basic problem is storage. My sunlight is good and I only need minimum storage if I have a way to use the power during the day and use a minimal at night. Are you telling me solar is not the path to get off the grid? Any help is appreciated.

Suit yourself, but a lot of experience and opinion, some of it on this forum and elsewhere is that power supplied by off grid PV systems is often or almost always more expensive than grid supplied power. Maybe your situation is different. I's suggest doing a bit of homework thinking like the devil's advocate to confirm your current opinion that off grid will be cheaper or less hassle.

[Logan005]

You can do it with a single 12volt battery and a panel. The question is can you afford to pay .50 to 1,00 plus per KWH, as opposed to your Poco who only charges 11. to 22 cents per Kwh. either way you will have to learn to live with a lot less electricity. and plan to haul out the batteries for replacement every year or so if you hard deep cycle your batteries.

[wingshadow]

It seems everyone wants to steer me toward the grid. I'm not going to connect to the grid. My question again is can I use a 220VAC power panel or will I need a different type connection? In other words will a 220vac output inverter be in anyway damaged damaged by using a standard power panel downstream that re re-routes the 220vac power to various 110 ac outlets?

[Logan005]

You can do whatever you want, you can backfeed an inverter into a split phaze panel. Again are you prepared to invest 12 to 14 grand into a battery every 3 to 4 years, or even sooner if you abuse them.

[sensij]

It seems everyone wants to steer me toward the grid. I'm not going to connect to the grid. My question again is can I use a 220VAC power panel or will I need a different type connection? In other words will a 220vac output inverter be in anyway damaged damaged by using a standard power panel downstream that re re-routes the 220vac power to various 110 ac outlets?

It depends on the inverter, but there are models that would be compatible was a standard split phase residential panel. If you don't want grid tie, then there must be no connection to the grid at all. What specific equipment do you have... If you are determine to go off grid no matter the cost, you can get good advice here on how to do it.

[wingshadow]

Ok so there are models that are not compatible. I need ones that are. I have a China supplier. This system I'm told is too large for Mppt I'm being told MPPT is limited at 96v and 30 amp so I'm looking at PWM. So far I am buying only the panels, I'm looking at a 20kw inverter to get my power and 192vdc input to the controller.

That's a lot of batteries in a single bank, so I'm looking at ways to put two inverters up and smaller controllers. One inverter handling 220 only and the other handling 110v. I don't like a single battery bank of that size. I've looked at lithium and aquion. Yes costs are high but I pay 25K to 30K to the power company every five years and they are raising prices again over the next few years. I have a lot of detail to work out, plus run a farm.

[Mike90250]

Ok so there are models that are not compatible. I need ones that are. I have a China supplier. This system I'm told is too large for Mppt I'm being told MPPT is limited at 96v and 30 amp so I'm looking at PWM. ..

Someone is flat out lying to you, I have one 3Kw array on a 150V MPPT controller (Morningstar) and a 2Kw array on a 200V MPPT controller (Midnight Classic 200) and they charge a single large battery bank (48V 800ah) and power a 240VAC split phase 6Kw inverter which feeds a full house (but no air conditioning) 2 fridges and 1 freezer. Runs a 1Kw water pump for about 3 or 4 hours a day for 300 trees irrigation. But I have to buy grown chicks, can't run a heat lamp 24/7 to raise hatchlings.

[sensij]

I have a lot of detail to work out, plus run a farm.

Until you are ready to give the grid-tie option a fair shake, I would suggest just sticking to running the farm. Wherever you are getting your information about solar, and what it might save you, you are being led badly astray.