New Solar System Planning

[Jirzlee]

I live in southern Wisconsin and I'm working on plans for a solar system. I'd like a system that is off-grid but would keep the utility for backup and larger loads as needed. It would be a plus if I could sell power back to the utility in the instances where I have extra solar being generated but I'm assuming that comes with some negatives and might complicate the system so I'm not completely set on that idea. Anyone by chance have WE Energies, southeast WI, for their electric and know how a grid tied system would work?

Looking at my electric bill my average usage is generally around 21kWh/day (~650kWh/mo) but ranges from 15kWh up to 35kWh/day in the hottest few months of the summer due to the central air A/C (heat is natural gas). The caveat to this usage is that I have a hot tub coming which is 240V rated at 48 amps on a 60 amp breaker (heater is 5.5kW). I think the hot tub might be too big to expect to run on solar without some specifically sized system but this isn't terribly important to me as I'm more concern with powering the more essential needs and appliances. Self sufficiency is one of the major draws for me towards going solar and the tub is more of a luxury of course.

The system I'm considering might be something like this, but I'd love feedback from anyone more experienced and willing to help. Nothing set in stone for sure:

Panels: (24) Renesola 370W Mono, 8880W total (having difficulty in finding any reviews on the quality on these but price is good for new panels, $.40/W (planning to mount on the roof of my attached garage, no shading except from the 2 story portion of the house shades the garage roof in the very early morning hours)
Inverters: (2) Growatt 5kW SPF 5000 ES-US, 10kW total (was also considering the MPP LV6548)
Batteries: (3) EG4-LifePower4 Lithium Battery 48V 100AH, 15.36kWh total

So how do I plan for which of my home circuits to actually run off of my solar system? I'm trying to gauge how much of my electric bill I can offset but also how useful the system will be in a power outage scenario.

My 2,000 sq-ft home has the following:
Refrigerator (newer LG linear inverter, would need to check the specs)
Freezers (2 new samsung uprights and 2 smaller chest style) - definitely would want to keep these and the fridge powered
Lighting / TV / etc
Electric clothes washer 120vac
Natural gas heated dryer with 120vac
Electric convection oven/range 240vac
Microwave
Dishwasher
Sump pump
Central AC
Natural gas furnace and water heater (can I run the furnace blower/electrical requirements with my setup?)
I have city water, no well pump

Open to any thoughts and suggestions on what I should try to run or changes to the system I've begun to lay out.

 

[SolarHead]

Not sure this will help you but what I did, and it was kind of some by design and kind of by mistake (it's how I roll). I got my inverter on the wall, my solar array up, got a critical panel installed. I used a gutter (aka , raceway) mounted to the wall underneath my main panels. My basement wall had two 200A panel boxes (I call them Panel A and B) before I got started on the solar project. The critical needs panel is the same brand and model as my two existing panels (Square D), I wanted it that way so I would have plenty of room in the critical panel, and the breakers would work when I moved them over. So, to get started, I moved my well pump breaker into the critical needs panel. Then I got things powered up, the inverter working, and then watched things work for a few days. Ran the well pump on pass-thru AC, on battery power, and on solar, just to see things work in different scenarios. My inverter does pass-thru AC to critical panel if grid power is available and its not enough solar, but it uses PV power to cover the critical panel during the day and when batteries are charged. All of this work was by design.

Okay, here's the work that was done by kind of mistake. I thought for sure I would start moving more breakers over to the critical panel and just load it up full so solar could cover it. Then I learned more about my inverter and discovered that it has a "limited to home" feature and a "limited to load". I used the "limited to home" where it covers the critical panels needs and any left-over PV power goes to one of my two main panels (I named it "Panel A") to solar-assist that panel as much as possible with grid filling in the rest. So, I left it that way for a few weeks thinking wow, I could really just leave the well pump breaker in the critical panel and nothing else and get benefit. But then I learned that my inverter would instantly stop sending power to the Panel A in the event the grid went down. So, I moved a few more breakers over to the critical panel, circuits like living room lights, kitchen receptacles, and so on as time went by. This was a way to ease into it and see what it would cover. If you're going to design the system and install it yourself, this easing into things is maybe the best way. If you're going to hire someone, they need to do a proper design to meet your needs before you buy any equipment.

Keep in mind, there's things that have to be done properly in regards to electrical codes and so on, but then there's the design itself that can change to suit your needs and what YOU want to do. Some people have big power tools in a shop they want to power (or not), some want to heat water and some do not. There seems to be different camps of people within the solar community. Some have a hatred for using grid power, some can't get grid power at all, and some are okay with using grid to fill in the gaps where the solar cannot, and some are off grid and have to really be careful about how much power they use to a point it's like rationing it. So, you design your system to meet YOUR needs and you're good. Looking at your list of appliances that you want to power by solar, you got some hefty loads there and I'm not sure your equipment will produce that much power. Central AC, Microwave, Oven, Clothes Dryer, right there you're kind of out of the ballpark. You can do a proper design like a designer would do by taking all the loads you want to cover, and starting there as a design start point. They work from that point backwards to discover what and how many inverter(s) you'd need, size of solar panel array, and then battery bank sizing. I have heard that pure 100% off-grid battery bank sizing and solar design is for old very well-experienced people. Grid-tied systems I think it's more common to find people that can design those systems because the design is much more forgiving. A proper design, or experiment like I did and kind of ease into it by moving breakers over to your critical panel.

All that said, if you haven't brought your equipment yet, you may want to look at the new Sol-Ark 15K, it has pass-thru AC for 200A, and they have a product coming out that its a panel for load balancing your loads. This is stepping more into the direction of a true home backup system rather than "bolting on" a solar system and seeing what it can power. I expect to see more and more products and solutions for breaker boxes. There's a few on the market now that are considered "smart" breaker boxes, that are kind of prepped for solar in mind, and products coming out that load balance so you're not using a critical panel and having to decide up front which breakers/circuits you want to cover, etc. I think its really exciting to see, in the next 3-5 years we'll see smart breaker boxes, load balanced, connected to solar, and it'll be an easier to hit the target so to speak. The days of getting an inverter, installing a critical panel, moving breakers over, are numbered I think. The products are getting more powerful, more features, and easier to manage.

 

[Jirzlee]

The SolArk 15k sounds good, pretty substantial investment though.

Are there any other inverters with this pass through function?

 

[acdoctor]

I don’t know what your solar irradiance number is for your location but I think you will have enough solar to carry everything but the electric range and you didn’t say water heater I hope it’s gas. If your blower motor is a PSC you should upgrade it to a DC x13. You may want more battery capacity than playing though.
My system is in my signature. I had similar electric bill.
The Schneider is similar to the solark separate solar charge controllers though. Also the pass through relay is like 60 amps. They are rock solid. I started off total off grid for a couple of years then started selling to the grid. At the moment I have 3900 kWh on my account I can use. I usually eat into that a few hundred kWh during the winter.

 

[Jirzlee]

So I've made a little progress on this project! Thanks for your inputs thus far.. I'm researching and learning in my spare time, but its kinda a slow process.

Yes, my water heater is gas, btw.

Panels:

Purchased (26) Heliene 370W panels from a local seller, so a little more total power than I was thinking: 9,620W vs 8,880W

• Panel Voc = 48.66v
• Temp Coefficient of Voc = -0.31%/°C
• I’m currently thinking of mounting them only on the roof of my garage. I could fit 12 on the SE facing half and 14 on the NW portion. I was going to do it this way since in the early morning there is a shadow that gets cast on that eastern corner. Here’s my roof, showing a rough idea of what the install would be: (disregard that white line)
• 
• (North is up ↑)
• The rest of the house is 2 story and I was trying to avoid mounting panels up there since I’m assuming I’ll need to brush snow off the panels from time to time in winter – I live near Milwaukee, WI…
• My roof angle is 22.6°. Azimuth angle is 135° for the side shown with 12 panels and 315° for the side with 14 panels. I did an online calculator and its saying the annual averages are:
• 4.45 kWh/m2/day for the 135°
• 3.34 kWh/m2/day for the 315°

Inverter(s):

I'm having some difficulty with this and trying to decide what would be best for me.

Currently on my list are:

• Schneider XW Pro 6848 6.8kW
  • So I understand that the MPPT charge controller(s) need to be purchased separately, I’m trying to figure out how I would configure and what I’d need to connect with my panels. Would I need to do 6 series, 2 parallel on 1 input and 7 series, 2 parallel on another input? But I think my total power may be over the capacity of the MPPT 100-600 Charge Controller. I read somewhere, “7kW or more”.
  • How quickly do all these separate components add up? I was looking at one of the Signature Solar “complete solar kits” and was looking up the cost on each of the listed components….for example, $1362 for the MPPT 100, $733 for the MPPT Disconnect RS, $652 for Mini PDP, $345 for InsightHome. Is there much more than that?
• Victron
  • Not sure what model might be the best fit for me. Was looking at both the Quattro and Multiplus II models. Would I need the Quattro to make it easier to hook up my little propane/gasoline inverter generator to charge my batteries if needed?
  • Do the costs for all the individual components add up as quickly with these as the Schneider?
• SolArk
  • Seems a little pricey but so are the above once you get it all together it seems.
  • Simpler install
  • 200a pass through
  • My understanding is that the communication is routed thru China or something??
  • High frequency inverter so not as good at bigger starting loads
  • Other pluses and minuses?
• Go cheaper with something like the EG4 6500EX
  • Pluses and minuses?

Batteries:

I am thinking of going with 6 of the EG4-LifePower4 Lithium (48v 100ah) rather than 3, or maybe even look at building a battery with a nicer BMS than what apparently comes on most of these off the shelf types.