smkettner
Well-known member
jimbo69ny said:
80%? Do you have any optional TOU rate plans?
Just a question for you guys with panels and an EV...
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80%? Do you have any optional TOU rate plans?
jimbo69ny
Member
smkettner said:
Im not sure what TOU means. I live in Central NY. Our electric is already quite cheap. Currently its around $.12/kwh
dgpcolorado
Well-known member
I drive about 7400 miles a year. And, yes, I heat with gas (used to be propane until gas lines got installed in this remote rural area). Water heater is on-demand (tankless) gas. I designed my house to be "sun tempered" so I get a lot of heat from the sun on sunny days in the fall and winter. And I dress warmly and keep the thermostat fairly low in winter: 62ºF mornings and evenings and 52ºF at night.QueenBee said:
Before I put in the solar panels I scored a 9.9 (99th percentile) on energy use for my household size and climate zone on the Home Energy Yardstick. To get better than that I'd have to heat with a woodstove. I do the little things: I don't own a clothes dryer, instead I strung lines across my oversize utility room to line-dry clothes (in my previous house I used the basement for that). I started using fluorescent lights in the mid eighties and my three most used lights are now LED. And, of course, I don't use air conditioning. My biggest power use, besides the furnace blower and the LEAF, is my home theater setup, but it only runs a couple of hours a day, on average.
Last year my 2170 watts of solar panels produced 3327 kWh of electricity. That's about 9.1 kWh a day or about 4.2 hours x panel wattage. Colorado is a pretty good solar location. Despite the snow.
Before solar panels and the LEAF, I measured my electricity usage at about 4.8 kWh/day, on average. I take conservation pretty seriously but I don't live a third world lifestyle.
GRA
Well-known member
ToU (or TOU) = Time of Use. Rates typically vary depending on time of day, day of the week and/or season, usually between peak and off peak, sometimes adding a super-off peak rate as well. ToU availability varies depending on the utility, and not all offer it.jimbo69ny said:
EV charging is typically done overnight at lower off peak rates. With grid-intertied PV, depending on whether or not you have net metering or separate meters, you can often sell electricity to the utility at peak rates during the day when you're not home using it, and buy it from the utility at night at much lower rates when you are home.
jimbo69ny
Member
Oh. I kinda thought thats what you meant.
One of the meters was upgraded to a "smart" meter but they left the other one the basic meter with the dial. I assume because the pv system on the smart meter was a larger system but I dont know. Like I said, it was all a mess.
One of the meters was upgraded to a "smart" meter but they left the other one the basic meter with the dial. I assume because the pv system on the smart meter was a larger system but I dont know. Like I said, it was all a mess.
RegGuheert
Well-known member
QueenBee said:
I agree with a high tilt for the solar hot water, since that prevents collecting WAY too much heat during the summertime. They look like about 60 degrees, which is about right.jimbo69ny said:
OTOH, I'm not sure I would have used flat-panel water heaters in NY. When it is cold, I expect the efficiency will be very low.
jimbo69ny said:
It appears from the picture that the entire available roof space is covered with PV. Is there space for more PV that I am not seeing?jimbo69ny said:
This might be an issue. I'm going to guess that the upgraded meter contains ALL the PV, but if you have a duplex, assumedly you have two houses using power. If you are on a net-metering arrangement, then you might find that one house gets no benefit from the PV and the other house only benefits until you produce more than was used. In other words, you will be giving free electricity back to the power company if the 8 kW array produces more electricity over the course of the year than you use in the ONE house. This is because most net metering arrangements do not pay you net electricity rates beyond what you use.jimbo69ny said:
But the devil is in the details. Perhaps you have more details about the arrangement with the power company?
KillaWhat
Well-known member
Ok, I know this has been touched on, but here goes anyway.
I'm currently about half way through installing a 4Kw PV system on the garage roof.
16 ET 255 Black on Black panels with 16 New style Enphase M250's
With no help or incentives here in PA, it's really expensive.
The problem I'm having is with the family and friends.
"What do you mean it won't provide power during a black-out? That's stupid!"
Etc.
Yes, I'm an engineer and I know about islanding, etc.
Having said all that....
I'm sure I could trick the M250 micro- inverters into producing using a small 240 vac pure sine wave inverter, and use the array to charge the Leaf.
I could then use the Leaf and the inverter to provide limited power for the house.
The Leaf would provide the needed load for the PV system, and I would disconnect from the street by shutting off my main breaker.
There would be some "critical races" like with the EVSE powering up, etc., but it should be doable.
Any thoughts?
I'm currently about half way through installing a 4Kw PV system on the garage roof.
16 ET 255 Black on Black panels with 16 New style Enphase M250's
With no help or incentives here in PA, it's really expensive.
The problem I'm having is with the family and friends.
"What do you mean it won't provide power during a black-out? That's stupid!"
Etc.
Yes, I'm an engineer and I know about islanding, etc.
Having said all that....
I'm sure I could trick the M250 micro- inverters into producing using a small 240 vac pure sine wave inverter, and use the array to charge the Leaf.
I could then use the Leaf and the inverter to provide limited power for the house.
The Leaf would provide the needed load for the PV system, and I would disconnect from the street by shutting off my main breaker.
There would be some "critical races" like with the EVSE powering up, etc., but it should be doable.
Any thoughts?
smkettner
Well-known member
I think it will be harder than you expect to trick the inverters. I might be wrong....
If you had a string inverter you could use the DC power direct through a charge controller to charge some batteries. Then another inverter to power the home or charge the vehicle.
There are some string inverters that will supply limited AC power to a separate circuit if the grid is down.
If you had a string inverter you could use the DC power direct through a charge controller to charge some batteries. Then another inverter to power the home or charge the vehicle.
There are some string inverters that will supply limited AC power to a separate circuit if the grid is down.
JasonA
Well-known member
We should talk... I'm using what's called a "blackout breaker" to trip once the grid goes dark.. then my APC 10kw Smart-UPS backfeeds into the whole house via one of their isolation transformers.
It keeps the micros happy and I can even keep power feeding into the APC with the gen for ext periods if nec (earthquake, etc). I've already tested charging the Leaf and Rav.. no issues.
Best way is just with a big UPS :lol:
It keeps the micros happy and I can even keep power feeding into the APC with the gen for ext periods if nec (earthquake, etc). I've already tested charging the Leaf and Rav.. no issues.
Best way is just with a big UPS :lol:
jimbo69ny
Member
Tubes suck. People always think they are better in colder climates because they deliver a hotter temp but they collect more snow in the winter. Flat plates are more reliable in colder temps and thats a fact.
Yes there is more space, they couldve put panels in front of the solar pv panels. There is plenty of room. They also couldve put panels over the garage which has nothing above them.
There are two separate systems one for the left side of the house and one for the right.
Yes there is more space, they couldve put panels in front of the solar pv panels. There is plenty of room. They also couldve put panels over the garage which has nothing above them.
There are two separate systems one for the left side of the house and one for the right.
NeilBlanchard
Well-known member
- Joined
- Oct 11, 2014
- Messages
- 619
This is my brother's house:
26 panels, 6.37kW, it generated 7.3MWh in the first year they had it. That is about 80% of what they use. Without the incentives, it should pay for itself in under 10 years. They heat with wood pellets, so they are very low carbon.
26 panels, 6.37kW, it generated 7.3MWh in the first year they had it. That is about 80% of what they use. Without the incentives, it should pay for itself in under 10 years. They heat with wood pellets, so they are very low carbon.
KillaWhat
Well-known member
JasonA said:
I figured you would be on top of this with your new PV array.
I'll drop you an email when I'm up and producing.
This sounds interesting, and with the UPS, pretty simple.
Thanks.
RegGuheert
Well-known member
Sorry, but snow is extremely unlikely to collect on any tube system with a 60-degree elevation angle. But the proof is in the pudding. Here is a side-by-side comparison in Ithaca, NY, (Where you live, right?) between a 64-sqft flat panel array and a 51-sqft (46-sqft active) tube collector on the same roof connected to identical systems. (Click on the link at the bottom-left of the page.) Note that the evacuated-tube system collected MORE heat last December than the flat-plate system which has 25% more area:jimbo69ny said:
In January, the flat-plat system only collected 11% more heat in spite of its 25% larger area. But what happens when you have a winter in which we get three-to-four-times as much snow as normal? Here is the plot for the winter of 2009-2010:
As you can see, the smaller tube system produced the same or more energy during the months of November, 2009, through February, 2010.
And this is true for arrays at a 45-degree elevation angle. IMO, both system should preform better in the snow (and in December) at a 60-degree elevation.
So, no, saying
is not accurate, even in Ithaca, NY.jimbo69ny said:
All that said, both systems consume about the same number of linear feet on the roof since the flat-panels in the comparison are 8-feet tall versus the tube array which is about 6-feet tall. So if you can handle the much higher wind loads and the worse asthetics of the taller flat panels, then you likely can save some money and produce a similar amount of energy for the same linear roof space.
Edit: Corrected the link since it has changed since I made this post.
PV2leaf
Member
The question about not being able to go from the DC that the PV panels produce directly into the batteries of our EVs is valid. The major reason why this is not practical is that the inverters that these systems are designed to use require significantly lower input voltage than a EV battery is configured for.
SMA inverters go on line at 300v and are most efficient at 250v but they can run with higher input voltages up to 480v. A good PV installer will design a system with string size based on panel performance and your local temperature considerations.
When it is hot your voltage has to get high enough to bring the system on-line but when it is -5F on a clear and sunny day your voltage mus stay below the value that will damage inverter. I believe the capacitors used are rated at 600V and you do need a safety margin.
You could always design a system for a much higher voltage and regulate down for both EV and inverter feeds but this would be expensive, create inefficiencies and the high DC voltage created for an input would drive additional expenses as most components are not rated for over 600V
SMA inverters go on line at 300v and are most efficient at 250v but they can run with higher input voltages up to 480v. A good PV installer will design a system with string size based on panel performance and your local temperature considerations.
When it is hot your voltage has to get high enough to bring the system on-line but when it is -5F on a clear and sunny day your voltage mus stay below the value that will damage inverter. I believe the capacitors used are rated at 600V and you do need a safety margin.
You could always design a system for a much higher voltage and regulate down for both EV and inverter feeds but this would be expensive, create inefficiencies and the high DC voltage created for an input would drive additional expenses as most components are not rated for over 600V
jimbo69ny
Member
Sorry man, come to NY almost all of the systems sold are flat plate.
Fact; snow gets stuck in the tubs.
Fact; flat plate collectors get hot and melt the snow off
Fact; flate plate are cheaper
Personal fact; I got a killer deal on the systems I bought. I purchased the remaining inventory from a defunct company so I bought a ton of equipment for a fraction of its value. So for me this was a no brainer. Either way, I never even considered tube collectors for many reasons
Fact; snow gets stuck in the tubs.
Fact; flat plate collectors get hot and melt the snow off
Fact; flate plate are cheaper
Personal fact; I got a killer deal on the systems I bought. I purchased the remaining inventory from a defunct company so I bought a ton of equipment for a fraction of its value. So for me this was a no brainer. Either way, I never even considered tube collectors for many reasons
RegGuheert
Well-known member
That's because they are cheaper and many like you believe they are less efficient in snow and cold when in fact they are more efficient in those situations.jimbo69ny said:
Perhaps if you mount them flat on the roof. But not in the tubes in the comparison I showed or any steeper installation. Here is a plot from that system during the Nor'easter on December 18 and 19, 2009. Note that only the flat panel production goes to zero during the storm, but the tubes do not go to zero because the snow does not block the light.jimbo69ny said:
Note again this test is from where you live. In the coldest months, the tube systems are 15% to 25% more efficient per unit area, including when there is massive snowfall.
This demonstrates how inefficient they are. Better not to accumulate the snow in the first place.jimbo69ny said:
Yep, as I noted previously.jimbo69ny said:
Good deal!jimbo69ny said:
...and some of those reasons were flawed.jimbo69ny said:
JasonA said:
is thread is rather old - do you have an update?
I use the APC SURT 6KVA with a Prius as a "generator" and have a variety of APC SUA/SMX UPSs for off-grid use with a 48 volt battery system (hobby of mine). I've often wondered if I could "fool" my SMA grid-tied inverter (4000 TL-US) with one of these pure sine wave inverters?? I worry most about too much PV power trying to back feed the UPS (in off-grid mode) and damaging the UPS. SMA indicated that the GT inverter will simply shutdown if the UPS goes down or no PV power being generated - so no issues there. I do have the option of using one of the larger UPSs with the iso-transformer - but don't know if the iso-transformer would prevent such damage anyway?
Now that I have a Leaf, with the use of level II charging, too much PV power may not be an issue if the Leaf's battery is substantially depleted each day - could possibly put safety shutdown with the APC "EPO" disconnect.
Have you looked into using your APC 10KVA system directly fed from the Leaf's battery (the SURT 8 and 10KVA use 400 VDC as the battery backup source). The big issue is they use +/- 200 VDC (center tapped) with the 4 battery cages.
Feel free to PM me if this is of interest as I've done some testing in this area.
