Retail Store + Home project

[NetComrade]

We have a small convenience store + deli. Its last months bill was 4000kWh.
It has a couple of coolers, a couple of freezers, and a couple heat generators (pizza, grill, panini)
It's heated and cooled by 3 (independent) 24K Mitsubishi Mr Slims
I am yet to look at savings on consumption side.

Since the beginning, I wanted to do solar. Just didn't have the funds. Now that funds might be avail, I want to look closer at solar.

The store itself is a "country store". For various reasons (east/waste sloping roof, looks, humangous sycamore tree), I don't really want to put anything on the roof of the store. The property has plenty of acreage though, and a 32x32 garage. The garage should fit 32 or so panels. half of the roof slopes south, half slopes north. That should give me 14,000 W of panels.. Maybe 30% to 50% of what I need (solar calculators say I need a 35-40K watt system). The garage does not suffer from any shading issues. The power company just did some additional trimming around it, as two power lines run close to it.

There might be opportunity to put solar panels elsewhere, however, many hundreds of feet away. What are my best options, if I wanted to still track my solar generation somewhat centrally. I was looking at SMA inverters and SunPower solar panels (currently on sale @ sunelec). I would like to hear other options.

The store also has a 7K tri-fuel generator (for emergencies, to run the coolers). The generator has not been hooked up yet.

The store has a small creek running underneath.. Doubt anyone would let me to hybrid power though .

Not to far from the store I also have a cabin that turned into our house. The house is 26x28 + 2 feet overhangs. It also has a 12x26 porch. The porch and 2/3 of the roof are south/southwest sloping. The north/north-east part can also be used, IMO as it has little slope. The roof has little shading issues. I plan on building a garage on the north side of the house, separated from the house by about 30 feet of driveway. The garage roof will also give me some opportunity to mount panels w/ no shading issues.

The house has a 4" conduit running from the roof to the basement for my solar needs. The house also has basement floor filled with a few loops of tubing for solar and/or wood warmed water for the winter. The higher eletric bills are in the winter (2-3x). The house is cooled/heated by a 36K Fujitsu mini-split. A wood-stove for emergencies is available. The house also has a whole-house external breaker, which I believe is req'd for solar installation. Lastly, the house has separate 12v wiring, which is in the walls but not yet hooked up for anything.

Someone locally (eastern WV) has two adjacent properties and he said you can generate electricity on one property and apply the credits to another. I am thinking I can generate a lot more at home than at the store and apply all the excesses towards the store.

I will most likely self-install with someone that has experience installing panels, but may utilize someone that quoted around $3 per watt including everything for installation.

I would like to have inverters which don't depend on some website to give information for me (like many micro-inverters seem to be).

I am looking for some general direction and product lines I should consider. Other than having local access to my solar data, my other requirement is expandability and (ideally) central management in each location. Lastly, in both the house and store, I would like to take the house "off the grid" during long power outages and take advantage of solar and generator power. I may not be thinking of other things.

Thanks much.

[Mike90250]

Welcome.

The first thing to consider the lifetime of batteries. They start to die slowly, the minute they leave the factory. If you use them, they die faster. So the continual replacement cycle cost of battery systems (4-10 years is a good guess) really makes them a much less attractive option than simple PV panels and grid tie inverter.

re: "24K Mitsubishi Mr Slims" If they are not energy star rated appliances, swap them out for efficient ones. Every watt you save, is a watt you don't have to generate. The product chillers and coolers in the store, are they efficient devices too ? Swap them out! Upgrades pay back faster (generally) then adding solar will.

Installing solar. Most utilities have plans for homeowners, check what exists for small business, it may be different. I never heard of site A, applying credits to site B, but more power to you if it works.

Backup generators or batteries ? Well, you need the backup generator anyway, because the batteries don't get recharged in a 3 day ice storm when there is no sun. If you can store fuel to run the generator for a week, that's very likely to cost you less then the first set of batteries. If you had several outages a week, and the generator was always running, battery & solar may be a winner, but if your area only has a few outages you can easily cover with fuel on hand, you don't need the complications an inefficiencies of batteries.

Hope this helps. Mike

[russ]

From PV Watts for a 1 kW DC system in Charleston, WVA - to give you an idea of what a system is capable of.

A 4,000 kWh/month system would be large and an off grid system very expensive. You are best off to consider a grid tied system.



1,243 kWh per Year *
RESULTS

2.60	70	7
3.17	75	7
4.32	109	10
5.27	125	12
5.57	134	13
5.76	131	13
5.80	136	13
5.51	127	12
4.82	111	11
4.08	101	10
2.80	69	7
2.08	55	5
4.32	1,243	$ 120

Find A Local Installer Download Results: Monthly | Hourly
* Caution: Photovoltaic system performance predictions calculated by PVWatts® include many inherent assumptions and uncertainties and do not reflect variations between PV technologies nor site-specific characteristics except as represented by PVWatts® inputs. For example, PV modules with better performance are not differentiated within PVWatts® from lesser performing modules. Similarly, the “Energy Value” column simply multiplies the utility-average electricity price by production. Complex utility rates and financing can significantly impact the energy value. See Help for additional guidance.

Requested Location	charleston, WVA
Weather Data Source	(TMY2) CHARLESTON, WV 3.5 mi
Latitude	38.37° N
Longitude	81.6° W
DC System Size	1 kW
Module Type	Standard
Array Type	Fixed (open rack)
Array Tilt	20°
Array Azimuth	180°
System Losses	14%
Inverter Efficiency	96%
DC to AC Size Ratio	1.1
Average Cost of Electricity Purchased from Utility	0.10 $/kWh
Initial Cost	3.30 $/Wdc
Cost of Electricity Generated by System	0.22 $/kWh

These values can be compared to get an idea of the cost-effectiveness of this system. However, system costs, system financing options (including 3rd party ownership) and complex utility rates can significantly change the relative value of the PV system.

[NetComrade]

I posted in a grid-tie forum and didn't mention batteries.

I have no plans for off-grid, except I'd like to be able to survive blackouts (e.g. disconnect house/business from grid, and use whatever energy sources I have available)
The 12V system I mentioned is completely independent, and currently has only one RV battery. In fact it now seems redundant (if I am going to have a solar system), but it could still be backup power to some of my vital electronics (which might be better off with a UPS). It's not worth being part of the discussion, unless you feel otherwise, IMO

The Mitubishis (MUZ-GE24NA) are 19 Seer. They're energy star too.
Not as sure about the rest of appliances. All of them were recently serviced, but some are rather old.

I did look a bit further into 'aggregate metering' and its limitations may not work for my case. I cannot afford a 40kWh Solar array (yet) anyway, so might as well start looking for ways to cut energy costs at the store.

I checked with a neighbor (that has aggregate metering). He has a 12kW system generating about 1kW a month since august using microinverters, about in line with what we'd expect during this time of year, IMO.

[russ]

I posted in a grid-tie forum and didn't mention batteries. Here is a quote from your original post "I would like to take the house "off the grid" during long power outages and take advantage of solar and generator power."

I did look a bit further into 'aggregate metering' and its limitations may not work for my case. I cannot afford a 40kWh Solar array (yet) anyway, so might as well start looking for ways to cut energy costs at the store.

I checked with a neighbor (that has aggregate metering). He has a 12kW system generating about 1kW a month since august using microinverters, about in line with what we'd expect during this time of year, IMO.

If you use solar when the grid is down you HAVE batteries.

[Amy@altE]

You say you don't want to go off-grid, but just provide power during power outages. That would require a huge (expensive) battery bank, and more complicated equipment for occasional use. I suggest you take the battery backup out of your plans, and use a generator for backup if you do need backup (what are you doing now for power outages?). A straight grid-tied system on your south and southwest roofs is a great idea. Do not put anything on the north and northeast roofs. Even though it may look sunny, it is not going to get direct sunlight, and therefore will be a waste of your money. You can use a string inverter or micro inverters, either will work just as well, the micros give you more detailed monitoring, but many feel module level monitoring is overkill. If you have a 200A Mains breaker box, I suggest you do not use anything bigger than a 7.6kW system for that location, otherwise you have to deal will the expense of changing up your breaker box to 400A. You may already have a 400A box at the store, in which case you can go as big as 15.2kW without complicated connections involved.

Amy

[thastinger]

In before the 7 digit cost estimate was revealed

[NetComrade]

Looks like I was naive enough to assume I can plug directly into inverters.
My previous experience was a 12v system on my RV, which sort of worked like that, as everything was (more or less) 12V there.
Looks like the only way to do that is with some SMA inverters that are very limited in wattage output (1500w).
Why can't I use the 208V output if I have 208V appliances?


Also, I am not entirely following 200A breaker panel and 7.6kW system.
I have a 200A panel, and 100A subpanel at home. If I recall correctly the subpanel was meant for the generator and/or maybe solar.

As far as north-leaning roofs go, why can't I rack the panels facing south on them? How much additional expense would that be? North leaning roof on the house is only about 15-20% slope.

[Sunking]

You need a GENERATOR end of story.

[Amy@altE]

NEC 705.12 allows you to have breakers adding up to 120% of the bus bar rating. What that means is if you have a 200A breaker box, you can have up to a 40A breaker for the inverter. 7600W / 240V x 1.25 = 39.58A = 40A breaker.

Your RV works because it has a 12V battery that it is connected to, and the inverter is getting its power from the battery. It is not sending power back to the grid, only charging from it when plugged into shore power.

UL1741 requires your grid-tied inverter shut off if the grid is out. SMA did a cool funky way to utilize the power from the panels while shutting off to the grid, but it is not a very stable power supply, any clouds that go by can drop the voltage down, so you risk brown out conditions. It is intended to allow you to charge up your cell phone and a few small thing, not run your equipment.

If you have 208V appliances, be sure to get a 208V inverter. They are mostly larger inverters, but again, if you are running on 208V, you probably have a big 3-phase box, and can likely handle a big 3-phase inverter. But again, without batteries, or a generator, you will have no power when the grid goes out.

If you want to use the north roof, yes, you can use a mounting system that raises the back of the panel. You will likely only be able to do 1 row, as you would have to have a large space between rows to prevent the front from from shading the back row.

This is getting to be a big project and sounds like a professional should be involved, this is too big for a self-install project.

[Mike90250]

I would like to take the house "off the grid" during long power outages and take advantage of solar and generator power. I may not be thinking of other things.

Batteries. Sorry, you just said it with a lot of words.

SMA does make an inverter, that has a small AC power outlet if the grid fails, but only when there is enough sunlight.

Anyway, grid tie is the way to go as you have heard.

[NetComrade]

Anyway, grid tie is the way to go as you have heard.

I appreciate so much affirmation and participation

I will get a few quotes for the house.

Thanks