|
One thing I confirmed during the blackout : the inverter stops when the grid doesn't provide power. This is a requirement by European norms : the time between grid's power loss and inverter switch off must be lower than 200ms.
Does your inverter has the same behavior ? In some regions, the power provided can have perturbations. Some inverter take some times to reset the mpp (max power point) tracker and resynchronize with the grid : up to a couple minutes. Some inverter are very quick to disconnect : 20-50 ms. From time to time I can have several microcuts per day, so some appliances are resetting. My inverter wait as much as possible (200 ms) before powering off when there is perturbations/power loss. Since my panels are connected I don't remember having any microcut, but 2 months 1/2 isn't significant enough to be able to say that my inverter "erases" these small perturbations. Denis. |
mine also shuts down if the grid voltage or frequency falls outside of certain parameters. It can disconnect as fast as .16 seconds for certain frequency and voltage issues, or up to 300 seconds for certain mildly low frequency problems.
|
Here are the whr #s from the last 7 days (Jan 28 - Feb 3)
Wed 720 thurs 180 fri 500 sat 520 sun 1300 :) mon 440 tues 780 |
Quote:
I've been looking over the specs of the Enphase stuff and read about the grid failure-system shutdown test. It seems like a reasonable test that should be preformed once in a while to insure that no PV power gets sent out on the grid during a power failure. I wonder if the Enphase minis can be used off-the-grid, by tricking them with a portable AC source? (Like an UPS(APC) or a gas generator)? Cheers, Rich |
Digital meter might explode??? ;)
Wow! After watching the installation video, this 700 watt system looks like it would be a snap for a DIY project.
GTe .7 But, when the home use was less than 700 watts, what would the meter do? (Mine looks kinda like this). http://www.griffmonster.com/miscella...tric_meter.gif Would it stall? Count backwards? :rolleyes: Or maybe read outgoing power as incoming power and add more to your bill?? Thanks, Rich |
I've heard if you have a digital meter they have to come back and install a second meter as they can not count backwards. Maybe things have changed in recent years, but that is one thing I heard.
|
If the meter is using an inductive pickup, I wonder if it can even tell the direction of power flow?
If it can't, and I fed my surplus power into the grid, the meter might actually go UP and I would be billed, as if I was the user, not the producer of that (backwards moving) power. Having two 'dumb' meters wouldn't help much, unless you piped all your PV power out of your house via the extra meter, and onto the grid. Not using any of it in your home, except via your regular meter. How they calculate the 'net' difference and deduct from your bill is another thing I'm wondering about.. That kind of two 'dumb' meter system wouldn't really work well, once people saw how easy it would be to steal some power. The more you steal, the more money you get back.. LOL! I think the old style mechanical meter would be the best way to go. It seems like a good Net meter should work like the old style mechanical meters! Edit: Just found this: Electric Meter for Net Metering ? - Solar Electric Discussion Forum by Northern Arizona Wind & Sun "This is bad - I'm being charged for power I'm making!" |
I have a mechanical meter on my house and it will run backward when backfeeding the grid.
We have had a huge warm-up here the last couple days. It was 60f yesterday (we were around -20f only a week ago) so the ground was soft enough for me to screw in a mobile home type anchor to help hold my array in place. It's a good thing too, we Are supposed to get high winds when the cold air moves back in tonight. Edit; conditions are almost nonexistant to allow backfeeding with my puny system. |
I forgot to write down my weekly #s :o. I'll update later, I'm at work now. I did have some good days though :). I'll try to get a # for a full month too.
|
Here are some watt hour #s for wed feb 4th thru wed feb 11th;
wed 1320 thurs 820 fri 1360 sat 800 sun 1080 mon 400 tues 1080 wed 20 |
Glad to hear you've got that array better anchored.
|
Last night was probably a worst case scenario. The ground was as soft as it usually ever gets, the array is still at the winter angle catching the most wind, and we had wind exceeding 60 mph.
It was still dark when I left this morning, but it looked like it stayed put. I'll look closer when I get home to see if it was pulling at it anchors. |
Good to know it didn't move on you!
Also, I'm liking the weekly updates. Its interesting to see the fairly wild fluctuation in power generation. I wonder if in summer if that will tame down? |
"backfeeding the grid."
Quote:
Trying to work with the power co. is something I don't have much interest in doing. However, I'm interested in the Enphase Micro-Inverters, but since they are not made for off-grid operation, I'm a bit reluctant to start buying them. I wonder if one could fool the Enphase units into thinking they were on the grid, by using a 220vac power inverter?? And then use the power on isolated house circuits that require power 24-7.?. |
Quote:
http://appliancetechtips.com/trouble.../dryerplug.jpg I remember one time when a fuse blew out on a drier. No heat at all, but the motor kept turning. My shirts were getting a ride, but stayed wet.. It was a 115V motor.. It sure seems like that neutral is going to be used to pass current whenever a load is placed between one of the hot sides and the neutral.. ------ "direction the power is flowing" IIRC, the specs on the inverters say they use a VERY small amount of power when the sun isn't out. You may not even be able to get a reading on your Kill-a-Watt. Cheers, Rich PS: I do Electronics, I'm not an Electrician. :D |
Quote:
I have seen nightime increments from time to time from standby loss. Most likely it was close to rounding to the next digit before night and it used enough standby to increment it. I don't count these nightime increments in my production #s I post. |
I've got a bunch of production #s here from Feb 12th thru Feb 24 2009.
Thurs zero Fri 220 whrs Sat 160 whrs Sun 1260 whrs Mon 1380 whrs Tue 1100 whrs Wed 20 whrs Thurs 480 whrs Fri 560 whrs Sat 100 whrs Sun 800 whrs Mon 1320 whrs Tue 1040 whrs |
Doesn't look too bad, but what happened on Wednesday?
|
"never measured any current in the neutral"
Re: "never measured any current in the neutral".
If you are only using your inverter to supply 230V Only devices, I can see how that could happen. But, if you plug in a 120V appliance, it's not going to be across the 230 lines, but one side of the 230 and the neutral.. So, if your 120V 60W lamp comes on, it's getting it's power from 120V & Neutral. What is your load?? Are you sending the inverter output to a 230V battery charger?? :) |
It's grid tied. The grid is the load.
|
Quote:
|
Quote:
http://i46.photobucket.com/albums/f1...roInverter.jpg Okay. Are you using the EnPhase AC Interconnect cable? If you are, is the Blue wire being used as Neutral? I suggest you find out why there is no current flowing in the neutral line. Logically that could indicate an open circuit from the inverter. I'm not an electrician, but as a home owner, I've wired up a 230V outlet in my own home (it passed inspection) and frankly, I'm a little worried that something is amiss with your hookup.. I've also built some 230 to 115 splitter cords for use with 230v gas generators. They use the neutral line, just like the one that came with my gas generator. http://ecx.images-amazon.com/images/...500_AA280_.jpg 230 in, and two 115 sockets.. If no current was flowing in the neutral, they wouldn't be working.. |
Rich,
Imagine a set of identical 120v ac loads, each connected from a different hot wire to the neutral of a 240v ac circuit. This is a balanced condition right? If you have a balanced load on a 240v ac circuit, how much current flows in the neutral? You need to look at the grid as a simplified and balanced load on a grid tied inverter. A grid connected 240v ac inverter should not have current flowing in the neutral. If there is current, then something is wrong. I'm not sure how Enphase has the neutral connected internally (just for communication?), but the grid tied inverters we are developing at work don't use the neutral. We don't want any neutral currents flowing. |
I see what you mean. Using a balanced load does the trick.
http://www.globalsecurity.org/milita...-424/f8-11.gif The Parallel load on the top rail perfectly matches the load on the bottom the load on the bottom rail. So, the two rail loads, both being of the same resistance, act as a voltage divider across the 240, with a perfect 120v on each rail. Causing zero current flow in the Neutral.. :D In my imperfect world, my wife is going to turn off one (or more) of those 100 watt lamps. That would increase the resistance of the bottom rail, upsetting the balance. Then there is going to be flow in the neutral.. Right?? ---- Humm, If the guys who designed the mini-inverter added a voltage level control on each rail. And then, used a current sensor in each hot line, to sense any imbalance in current flow.?. They would be able to compensate for the imbalance by boosting the voltage on one rail, until there was no more current on Neutral! Hey! Perhaps that's how they are able to dump the full 200W onto an unbalanced grid!! |
Quote:
|
Quote:
(*) Under 100W displayed by my inverter, the meter is under, while it's over when the inverter displays more than 300W. Since the connection to the grid, the (selling) meter is 8% faster than the inverter ;) If clouds can mask, this morning the fog wasn't preventing luminosity as much as the freezing of yesterday. Denis. |
I calculated the last 30 days production, starting feb 1st 2009.
My solar array produced 22.38Kwhrs during this time. The spring angle change is overdue. I hoped to do it a couple weeks ago when my brothers were over, but it was very windy, so we decided against it. |
Yay, 22.38 kWh ... that's just about enough energy to heat my uninsulated apartment for 24h when it's about -8C out. :)
Will your Spring angle change be "ahead" of today's optimal setting, so it reaches optimal again half way between now and your next planned change? |
I'm very curious as to what % of your total usage is generated. I realize its likely very small, but I'm still quite interested.
|
Quote:
When I get my latest electric bill, I plan to compare useage to production. If I were watching my utility meter better I wouldn't have to wait for the bill :o. |
1 Attachment(s)
Changed the array's angle over the weekend finally. It's now at 40 degrees, optimised for spring/fall sun. I noticed better power into the evening compared to the evening before the angle change with similarly sunny days.
When I originally built it, I didn't built with spring summer angles in mind (for some wierd reason) so I had to add support in the middle of the array to keep it from sagging :o. |
It looks pretty good. How have your numbers been lately?
|
They were pretty bad until late last week when the sun started shining again. I had 2 record days in a row over the weekend. I'll post some #s soon.
|
Here are production #s from Feb 25thru march 16 2009;
February 25=520whrs 26=500 27=200 28=1360 march 1=640 2=1320 3=1320 4=1380 5=500 6=1100 7=20 8=20 9=180 10=20 11=820 12=880 13=1410 14=1460 15=1300 16=1280 Someday I should graph my #s :). |
Interesting sway in numbers, really bad from the 7th to 10th, then really awesome from 13th+.
|
Here are some monthly production #s.
For all but the first 6 days of january, 13.18 kwhrs (the array went on-line Jan 7th) averaged 549whrs/day. For the 28 days of February, 20.42 kwhrs or an average of 729.3whrs/day. For the month of March, 26.31 kwhrs or an average of 848.7whrs/day. |
I just noticed that in 4 days it will be time to change the angle of the array for summer already :eek:. I guess I better figure out what size legs to make. Maybe I can just move the bottom of the spring/fall legs to get the angle.
|
Not too horrible of a setup for free. Still any idea of what percentage of your total electric use that is?
|
I just checked my last utility bill and averaged the last years electric consumption to 21.7kwhrs per day. So in a month I can make up 1 day's worth of consumption. What's that, like 3.3% or so?
|
I had 2 different power outages in April. One was just long enough to erase the Kill-a-watt memory and the other lasted 25 hrs. So April production was 25.74 kwhrs, or about 919.3 whrs/day (using 28 days because of power outages).
On May 10 th I changed the array to the summer angle. The month of May saw 32.88 kwhrs of production, or an average of 1061 whrs/ day. I need to try modding my kill-a-watt to have battery back-up. |
| All times are GMT -5. The time now is 02:35 PM. |
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger