diy solar

diy solar

Adding storage to my Enphase system

I lived in Los Angeles for 15 years and felt some good earth quakes.
Since I lived close the the ocean the ones I felt were muffled from the sand. At least that's what I heard. They seemed to move more sideways.
But I did feel a couple inland and they were loud and more up and down.

It's amazing how wood houses just flex all over and hardly have any damage.
 
Back in the 1989 Loma Prieta quake, houses nearby in the Santa Cruz mountains mostly saw things like drawers sliding open, or water sloshing out of a pool. 50 miles away in San Francisco, houses built on filled-in areas of the bay collapsed. The SF Bay has been getting filled in for 150 years.
I drove through Oakland and saw houses standing, with a pile of bricks in the yard and a chimney-shaped hole in the side of the house.

Of course, not all homes had their mud sills bolted to concrete foundation, so some jumped off. Cripple walls sometimes collapsed to the side. Second story dwellings above garages sometimes became ground floor. There are brace designs for the couple feet of wall on either side of garage door to give them strength. Newer construction techniques use metal straps to tie wall studs of one floor to the floor below.

The story from the great quake of 1906 that wood-framed houses survived where brick houses collapsed, but were consumed by the fire which followed, was a lie. Even the insurance agents were in on the arson scam, because their houses weren't insured against the earthquake that destroyed them, but were insured for fire. (That 1906 quake was one point higher on Richter scale or 10x the power of Loma Prieta quake or Northridge quake.)
 
My location, roof mount under 40# per attach point and under 18" high, no structural permit. Ballast requires one.

For you, back to my idea of joists bolted to parapet. In my location we can build a deck (on the ground) < 18" high without a permit.
Fire department says they can step over minor obstacles, walkway on roof doesn't have to be 100% clear.
How about putting deck boards on my suggested joists, so it is a walkway rather than a series of tripping hazards?

Orient the joists from street to house, so not in the walkway? (do periodic cutouts on the bottom to let water pass under.)

Alternatively, glue down panels? Or make standoffs, and glue them down? Glue down deck boards as runners (more area to bond), and screw standoffs or Z-brackets into them?
Glue sounds good since there's no holes.



 
The first two are from 2016 and 2018, so what happened? I have not heard much about either of them. The third one looks cool, and would probably work for my setup, but it is only carried by installers, does not look like a DIY install.
 
The first two are from 2016 and 2018, so what happened? I have not heard much about either of them. The third one looks cool, and would probably work for my setup, but it is only carried by installers, does not look like a DIY install.
Hedge's way is better. That'll be a lot cheaper anyway.
People glue panels to the top of RVs. I doubt you'll need that much holding power.
Attaching the panels to blocks would probably be safe too.
 
Hedge's way is better. That'll be a lot cheaper anyway.
People glue panels to the top of RVs. I doubt you'll need that much holding power.
Attaching the panels to blocks would probably be safe too.


The trick will be what flies with the inspector.
"Blocks" as in concrete cinder blocks would be "ballast", so requires more jumping through hoops.
"Adhesive" as an alternative to "screws" might be no problem at all.

Framed commodity panels are usually cheapest.

Why not run boards all the way from parapet by the street back to roof of house? Even if walkway required on sides, that would be left clear.
Since permits are a hassle, cover the entire length with panels even if you don't need them all right now. Overpaneled due to not having ideal slope.
 
I basically want to glue down the concrete blocks, and then screw the panels to the blocks with the 90 degree angle brackets.

20 12x12x2 inch blocks glued to roof with patch tar
36 angle brackets

It's is so much less to buy, so of course it can't be legal.
 
You could make up a plan and take it to the permit office to see what they say.

I haven't decided whether I will get a permit or not when I add panels.

I don't want the electric company to demand that I buy extra insurance.
Convincing the building department and the electric company that I will never send 10K to the grid might not be easy.

I told the electric company my panels generate 9.9K DC and my inverter will never put out more than 9K AC.
They seemed to believe me. They put in my bi directional meter today.
 
Congrats on getting te system passed and having your meter installed. Looking forward to hearing how it all works.

My additional panels are just going to charge my backup battery. They will not have any direct path to put power out to the grid. All of my solar is only connected back to my main panel by the original 20 amp breaker for the Enphase system. Even if I mess up in the programming, the worst case is I trip the 20 amp breaker. The way I am setup, the Enphase is the only thing that ever pushes more than 500 watts out to the grid. The Schneider will only push a maximum of 3 amps to my main panel, and only from 4 pm to 9 pm, and only if the Enphase is pushing less than that 3 amps. All of the rest of the power is consumed by the loads in my backup panel. And under most times, my main panel uses most of the 3 amps, leaving just a small back feed. When large loads do come on in the main panel, like my A/C , I will be consuming power from the grid.

If I ever do get the PLC working correctly, I want to have it kick up the main panel export when the A/C is running to help power it from the battery bank. But that is a future project.
 
I made an interesting observation today.

It is horrible dens overcast. My solar production is crap. I peaked at just 1.0 KW and it has ben floating under 600 watts most of the day. Right now it is only 300 watt, when I had 3,300 watts at the same time yesterday. So, I made the choice to turn down the charge current so I am not sucking grid power to charge my battery bank. I know it will not make a full charge, but I will have some if the power does end up going out. So I went into the config page and dialed down the charge power to the lowest it would let me, 5%. That is % of maximum for the XW-Pro. Maximum is 140 amps, so 5% is 7 amps. I clicked on force bulk charge, and there it is, putting just 6.85 amps into the battery bank. It has not even pulled the voltage up 1 volt in 4 hours, but it is going up. I am also going to either disable, or turn the grid support power way down, but in any case, I will only let it run down to 51 volts again, so I have some reserve.

Now the "interesting" part.
As I am here at the computer, I have the Schneider monitor screen up and I glance at it from time to time. I see the battery current fall to near zero. Hmmm. Why? As I look at it, it resumes charging at the low 7 amps a minute later. I pop up the battery summary graph, and I see it has done it a few times, where the current was down near zero, typically only a minute or two, a few times. Hmmm. Never saw this before. I would see some tiny dips, maybe 2 or 3 amps, but this was dropping, 6 out of 7 amps, so it looks like a huge drop. I finally made the connection. The microwave is being fed off the backup loads panel, and when the microwave is running, it is causing my charge current to drop. I normally never see this. But what I think is happening is it is reducing the charge power to limit the power it is pulling from the grid. Normally I would have a bunch of power coming in from the backup load panel from the Enphase solar, but today, the power just is not there. Down to just 200 watts as I am typing, and yes, all 16 panels are "producing" with every panel having made about 300 watt hours today. In the toolkit, the power the last minute was only 151 watts, 8 watts from each panel.

It hit 4PM while I was typing this, and it went to start pushing out 1.5 KW. I tried turning it down, but it really wants to power the backup loads panel, AND feed some back. I ended up just turning off grid support. My battery will rest at 65% until either the sun comes out, or we have a power failure.
 
Ok, I made a few adjustments. Now it is in "Load Shave, so it is supplying 200 watts to help power my backup loads. It won't take long to bring the battery back down to 51 volt cutoff, but I will shave off a little of the $0.43 power between 4 pm and 9pm. And it is all still solar power as I kept my charge power below the dismal solar output today.
 
I have check a box that says Solar Sell and I think that will cause excess to go to the grid.
It is set to sell 9000W max.

I also have an option called Grid Peak Shave. I don't know what that does.
 
That is probably similar to the "Load Shave" function in the Schneider. That is what I am doing right now, it uses the inverter to make up the difference. Right now, my backup loads panel is drawing 1,000 watts. I told it to only allow the grid to supply 400 watts, so the inverter is now pushing out 600 watts. "Shaving off the peak". I am going to lower it a bit as the battery is already half way down. There, I upped the shave threshold so it is now taking 700 watts from grid and only 300 watts from battery.
 
I also have an option called Grid Peak Shave. I don't know what that does.

I would expect it to reduce consumption from grid as far as possible, supply 100% of consumption from battery and draw zero from grid during times of peak rates if possible. Might also maintain a reserve of some power for grid failure?
 
So I went into the config page and dialed down the charge power to the lowest it would let me, 5%. That is % of maximum for the XW-Pro. Maximum is 140 amps, so 5% is 7 amps. I clicked on force bulk charge, and there it is, putting just 6.85 amps into the battery bank. It has not even pulled the voltage up 1 volt in 4 hours, but it is going up.

I was adjusting charge current the same way, but after some playing around, I set the max charge current where I want my absolute max. I the move "EPC Maximum Charge Power" (under "Power Control Settings")

This allows me to set any charge current I want, well not current, the units are watts.
I have set it to 100 watts and 2000 watts, it follows closely and tries to stay just under your commanded maximum.

It also means I can look at my back feed to the grid and adjust my charging to something less than the back feed.
 
I don't have that setting under the 1.03 firmware. I will have to update mine to 1.12 soon as it does sound like they have improved a few things.
 
Southern California Edison is getting pretty annoying. They still are not posting any usage data. It has been blank since April 1st. My billing period ends on the 18 of each month. I was flying blind trying to balance out my charging and grid support, but I must be doing something right. For the very first time since I put in solar, I got a full month bill with a negative balance. SCE has a credit on my bill of $16.97 for the period from Mar. 18 to Apr. 17 where I exported a net 4.48 KWH per day on average. Same time period last year, without the battery, I was a net user at 4.07 KWH per day. A big chunk of the difference was the solar production has been better this year, but also pushing 5-7 KWH from solar noon to the peak rate time is also helping a bit. I may be throwing away 1 KWH in the losses from the charger, battery round trip, and then inverting again, but it seems to be paying off. I know I won't be having negative bills once I have the A/C running in the heat of summer, but with these sunny but cool days, my system could theoretically run off grid. I am only using about half my battery's usable capacity, and then using the grid to store a bit more. To run off grid, I would be close to maxing out the battery each day. I do want to add a bit more storage. I am debating if 50% more would be enough, or should I just double it?
 
I know I won't be having negative bills once I have the A/C running in the heat of summer, but with these sunny but cool days, my system could theoretically run off grid.

With time-of-use rates, A/C off peak is a fraction of the cost on-peak.
Have a practical and cost-effective way to store cold for use late afternoon?
 
My house has decent insulation. Running the A/C basically constant from 10 am to 2 pm should get the house pretty cool. Hopefully not uncomfortable though. It was only up to 80F out when I did it, so it is not a good test yet. We did not need any more A/C as it was cool out in the evening again. I have only done this 2 days so far, but I will try it more this summer.

My A/C system is a newer multispeed Carrier system. The compressor unit only has an on/off electrical control from the thermostat, but it has a demand control valve that works off of the refrigerant pressure. I will have to see if it is better to keep it in the low speed mode, or if it actually moves more BTU per watt hour in the high speed mode. When the thermostat calls for cooling, it comes on at a low speed. The air coming out of the vents is quite cold, but low velocity. A valve in the outdoor adjusts the operating pressure based on demand so the power consumption follows the heat being removed. I have not found charts on what the pressure and current values should be. If the system runs for more than 14 minutes, it will kick to a higher speed on the indoor fan unit. The increased air flow will cause more heat to be absorbed, so the valve in the outdoor unit will adjust and increase the cooling capacity and current draw. So I have to decide, do I let it go to high power mode, or intentionally cycle it at 13 minutes to keep it in the low power mode?
 
... I have not found charts on what the pressure and current values should be.

Or are you looking for an R-134a psychrometric chart?

(@Supervstech can probably recommend better, but here's a quick description on how to use such a chart http://www.alephzero.co.uk/ref/circeff.htm if you're not familiar with them)
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