Northwest Ohio, I need help designing system

[gary c]

I have 34 540 watt bifacial panels , ground mounted. The local utility is a coop (privately owned) and NOT solar friendly. Being privately owned they do not have to go by the laws Ohio has passed to encourage solar. In order to have generation to supply my winter needs I will end up producing about 174% of my annual usage. If I net meter I have to go with the utility's supplier since they require 120% or less. There is a $2000 connection fee and a $100 per month net metering charge. They also will "negotiate" my metering rate. Bottom line I think I have enough generation 18Kw to go off grid. I want to stay connected and use the grid as a back up through the first winter. I am looking for a inverter that is around 6Kw and I plan on around 20Kw of battery back up. The inverters I was looking at have a max input and could not take 18Kw. Are all inverters like that? I am pretty much doing this myself because everyone I've talked to wants to sell me a bunch of things I don't want or need. I do have an engineering firm that will design the system once I have components. So many questions. Micro inverters for example? Is there someone I can hire who will work with my needs. Thanks for reading. Gary.

[organic farmer]

... I have enough generation 18Kw to go off grid. I want to stay connected and use the grid as a back up through the first winter.

That sounds like a good plan to me.

also dont delay on planning how you are going to perform 'equalize charges' on your battery bank.

[bcroe]

Gary, Just about everyone going off grid is heating with firewood, is
that your plan? I heat with the latest heat pumps, which are very
efficient. But it works because I collect a big summer KWh surplus
on my net metering plan (no extra charge here in N IL) and take it
back in winter. There is no way off grid to store the 13,000 KWh
summer reserve I will need for winter. Is your plan a battery of
20KW maximum discharge rate? Check the KWh capacity.

Also check the stickey on ways to reduce snow accumulation on
your panels. good luck, Bruce Roe

[gary c]

I should also note. we have heated with wood for 38 years. We have a Fire Chief wood burning furnace with a cold air return, barometric damper and 4 tiles for outside air so we use all outside air for the fire box. We can maintain a 80 degree difference between the outside and the inside temperature of the house within a 4 degree range for 8 hours on one stoking of the furnace We have an 80 gallon hot water heater with a brass liner that runs through the furnace with a circulating pump that runs for an hour each morning. I generally turn the electric hot water heater off later Nov through early March.

[organic farmer]

I heat with wood, most homes in my township do.

We use a cheap [less than $300] woodstove that heats circulating water, which circulates to a thermal-bank, which then circulates through our radiant flooring. We have a solar thermal array all setup, but I over-pressurized it and caused a lot of internal damage. Overall it is designed so we can easily shift from using wood as fuel or using solar as fuel. In both cases the heat sources are rated at 3X more than how much heat we need for living in Maine. I just need to get motivated to spend a summer repairing these solar thermal panels.

[J.P.M.]

What are your reasons for all the PV ?
Is economic benefit one of them ? If so, my guess is you're looking at a long payback/low ROI.
Such a system as you anticipate will probably generate something like 25,000 kWh/yr. with a 45 deg. tilt.
All that said, if you haven't done so already, do a few PVWatts runs with the goal of maximizing winter output.
I'd suggest you consider a vertical array, with a mostly south facing orientation as that seems to maximize winter output in NW Ohio. such an orientation produces an annual output of something like 950 - 975 kWh/yr. per STC kW, with about half of that production coming in the Nov. - Mar. period.
With the vertical orientation, you might just also get some benefit from a bifacial panel.

Vertical orientation will also keep the array mostly snow free as long as you keep the arrays high enough off the ground to avoid snow buildup. Just don't forget about drifts buildup in front of the array.
Depending on your winter loads, which it seems will set the system size, I think you might want to bone up on string inverter sizing as f(array size). With a grossly undersized inverter as your numbers show, you'll get some serious clipping.

But after all that, and given your POCO's stance on PV, I'd wonder about the practical and financial viability of the project.

[bcroe]

In order to have generation to supply my winter needs I will end up producing about 174% of my annual usage. Gary.

That is about the way it works. I might collect 3000 KWh in a summer
month, 1000 KWh in a winter month. A pretty innefficient use of
resources. Fortunately Net Metering here cures that loss, at no cost
to me. Bruce Roe

[gary c]

I started out to go the net metering route. The local utility trades even for generation that is used while generating. Any excess during the day they pay wholesale for and what you use at night you pay retail for. There is no banking of excess generation. I ended up working a great deal on panels and racking and decided to see if I could generate enough to now have to mess with the utility. Yes net metering would be nice but I also wanted to have power when the grid went down so was looking at hybrid inverters until I was informed that since I was going t o generate too much power the utility would no longer let me be a customer but I'd have to go with their supplier. I want to use them as back up only. It is what it is. I have a great resource and am looking for advice on how to most efficiently use it. I am looking for product recommendations.

[J.P.M.]

I started out to go the net metering route. The local utility trades even for generation that is used while generating. Any excess during the day they pay wholesale for and what you use at night you pay retail for. There is no banking of excess generation. I ended up working a great deal on panels and racking and decided to see if I could generate enough to now have to mess with the utility. Yes net metering would be nice but I also wanted to have power when the grid went down so was looking at hybrid inverters until I was informed that since I was going t o generate too much power the utility would no longer let me be a customer but I'd have to go with their supplier. I want to use them as back up only. It is what it is. I have a great resource and am looking for advice on how to most efficiently use it. I am looking for product recommendations.

That much off grid design will make things about as expensive as an entirely off grid system not only in $ cost but in maintenance and reliability. It is what it is.

[SunEagle]

That much off grid design will make things about as expensive as an entirely off grid system not only in $ cost but in maintenance and reliability. It is what it is.

I agree with you. Having a system like that is not cheap and IMO is still more expensive then having a total connection to the POCO.

[gary c]

Thanks for all the opinion. Does anyone have any helpful information or suggestions

[J.P.M.]

Thanks for all the opinion. Does anyone have any helpful information or suggestions

You're most welcome.
Yes. A respectful suggestion: Learn more about solar energy and its limitations before you go further. Reads to me like you don't know what you don't know.
Take what you want of the above. Scrap the rest.

[SunEagle]

Thanks for all the opinion. Does anyone have any helpful information or suggestions

I am just trying to help you not waste your money. Going off grid is very expensive and will require a lot more of your time to watch and maintain your system. A grid tied solar pv system will still be cheaper and more reliant in the long run regardless of who your POCO is.

[Mike 134]

Thanks for all the opinion. Does anyone have any helpful information or suggestions

From your first post "I have 34 540 watt bifacial panels , ground mounted."

Now you're looking for information?

[gary c]

I admit having the panels first was a backward approach. Long story, but that is where I am at. Is it a good idea to avail myself of the design capabilities of various suppliers to get ideas?