2020 Solar PV Performance

[Agent]

I'm a bit late to the party, but who doesn't like more data. 7.9KW system at 44 degrees Latitude in WI: Ground mounted at 45 degree angle facing due south, and routinely brushing snow off as well.

It's too bad that our net metering is only on a monthly basis, so no banking summer credits for me.

And this year I even had an inverter kick the bucket in November, and was down for almost three weeks.

 

[Rusty18]

No solar system here...yet. I’m planning on putting about 1kw worth of panels on the roof and running to a few batteries then pulling off of that to run a window ac unit in the summer and (partially) run a small electric space heater in the winter. (no tie in) (added bonus will be power for the stove without having to run the generator)

I’d like to have about 12kw on the barn roof (perfect orientation and slope) and do a grid tied system but the quote for all of that was about$28k. I can’t bring myself to go back to living on credit even though the figures clearly show it will pay for itself in less than 10 years.

 

[stoveliker]

I'd consider a bit larger PV system and a minisplit... Way more efficient for the same output(s)

 

[Rusty18]

I'd consider a bit larger PV system and a minisplit... Way more efficient for the same output(s)

Mini split will be in hopefully before next winter, just trying to get some solar started. And once I get started I plan on adding capacity as the budget allows.

 

[ABMax24]

Can you explain how you are compensated when your Net goes negative?
Are you simply compensated for the Net negative at the Wholesale rate of power?

Apparently I missed this.

Yes I am repaid at whatever my retail rate for electricity is. I pay 2 portions of electricity, the retail energy charge, and transmission/distribution fees. Our system is called net billing, not net metering like many places have. I receive credit for the energy I sell, but not the transmission/distribution fees.

My bill is consolidated on a monthly basis, so every month I have a surplus I get paid for. The reality is I always have a bill, even on the best months my bill is about $10 due to fees. If I had a larger system and actually had a credit at the end of the month it would be carried forward to the next month, if at the end of the year I still had a credit I would be issued a cheque.

Here in Alberta our micro-generation legislation states the utility must allow a system size that covers up to 100% of annual consumption. To go larger than 100% would solely be up to the discretion of the utility, mine is 115% and they were fine with it, but they might take issue with a system 150% or larger. So annual credits really aren't a thing here.

 

[stoveliker]

Here (Long island NY) it used to be that there was a reconciliation date once a year. I.e. if at that date the meter was negative with respect to the reading a year ago, one would get paid the power generation cost of the kWhs.
When I had my panels installed (2018), the reconciliation date had been cancelled. Meaning my meter continues to go backwards year after year for 15 or 20 years as I overdimensioned my array in expectation of an AC system - which turned out to be far more efficient than I had expected).

So maybe I need to get myself a phev (or use my minisplit more in winter - but I like using the BK so much...)

 

[peakbagger]

Wow, the Alberta deal does not sound that attractive to encourage solar unless I am missing something. Power looks cheap so I would wonder why anyone would spend the money beyond altruism or a grid backup with a hybrid system?. With a credit for generation only not T&D and no way of banking credit ahead what am I missing?

At near 45 degrees latitude I have significant seasonality for my production and my usage. I need to have access to the grid as a "battery" so I can build up credit in the summer to make up for abysmal production and much high usage in winter. I probably still would have solar but a lot less of it. I am also lucky that I don't have a reconciliation date so I can carry a credit forward.

Most states used Net Metering as a "carrot" to get solar installed. In my state, NH, they needed a big carrot so we got a very generous net metering rule. The trade off is we had near zero solar installations due to the high cost of equipment. My first small system was learning system for me and even though I did my own install, its payback at best is decades. I have some other friends who put in a much larger system and they just regarded it as big down payment on future power bills. This was before the US government passed the 30% (now lower) tax credit for solar. That got the production of equipment up which dropped the price substantially. When I first looked at solar, panels were $10 a watt, I got a "great" deal at $6 a watt. When the federal tax credit was passed panels dropped to $2 a watt and with Chinese dumping of the panels, bulk panels are in the $0.50 range with deals getting as low as $0.30. The reality is that subsidies are no longer needed in most areas as solar is getting down to a four year payback but getting people weaned off tax credits is not easy. My state had a cap on net metering of 1% of the installed generation, that was bumped up to 2% and there is pressure to do it again but the general thought in the legislature is to sunset some of the net metering benefits.

 

[ABMax24]

Wow, the Alberta deal does not sound that attractive to encourage solar unless I am missing something. Power looks cheap so I would wonder why anyone would spend the money beyond altruism or a grid backup with a hybrid system?. With a credit for generation only not T&D and no way of banking credit ahead what am I missing?

At near 45 degrees latitude I have significant seasonality for my production and my usage. I need to have access to the grid as a "battery" so I can build up credit in the summer to make up for abysmal production and much high usage in winter. I probably still would have solar but a lot less of it. I am also lucky that I don't have a reconciliation date so I can carry a credit forward.

Most states used Net Metering as a "carrot" to get solar installed. In my state, NH, they needed a big carrot so we got a very generous net metering rule. The trade off is we had near zero solar installations due to the high cost of equipment. My first small system was learning system for me and even though I did my own install, its payback at best is decades. I have some other friends who put in a much larger system and they just regarded it as big down payment on future power bills. This was before the US government passed the 30% (now lower) tax credit for solar. That got the production of equipment up which dropped the price substantially. When I first looked at solar, panels were $10 a watt, I got a "great" deal at $6 a watt. When the federal tax credit was passed panels dropped to $2 a watt and with Chinese dumping of the panels, bulk panels are in the $0.50 range with deals getting as low as $0.30. The reality is that subsidies are no longer needed in most areas as solar is getting down to a four year payback but getting people weaned off tax credits is not easy. My state had a cap on net metering of 1% of the installed generation, that was bumped up to 2% and there is pressure to do it again but the general thought in the legislature is to sunset some of the net metering benefits.

No it's not that great compared to other areas. When I installed my panels there was a rebate of $0.90/watt from the provincial government to help offset installation costs, this rebate has now ended. As far as electricity prices go, there are no feed-in-tariffs or otherwise to boost the price for renewable energy, now if any large consumer want to sign a PPA with a renewable generator for a higher price they can. I had originally calculated my simply pay back period to be 18 years prior to knowing how much we would self consume. I now calculate that to be closer to 12 years, using our 35% self consumption rate and updated power prices. There is no doubt I would have been better off to invest the money from the system and make higher returns, but the general consensus here is solar doesn't work and is a waste of time and money. I could get the math to pencil out, so went ahead and bought the system, as much in an effort to prove that thought wrong, overall I'm happy with the system and is a hedge against the inevitable rise in power prices.

As far as small electrical consumers are concerned we have a couple options; our electricity connection is provided by the wire service provider (WSP), but the actual electricity is provided by another retailer, this retailer can be the same as the WSP on a regulated or variable rate or we can choose another retailer. I have chosen a retailer that also has the option for consumers to pay an added fee to purchase renewable electricity. As a generator I have the option of 2 rates, currently 22 cents/kwh and 6.5 cents/kwh, and they allow us to switch twice per year. I switch to the high right at the spring equinox, and switch back to the low rate at the fall equinox. Allowing me to get paid more when I have an energy credit, and pay less during the winter.

With Alberta's system there is incentive placed on self-consumption of the energy generated, to avoid paying the transmission fees, and we deliberately time things like the dishwasher and washing machine to run during peak daylight hours. Although at the current time there isn't enough cost incentive to justify a house battery.

We sit at 55.2 degrees latitude. Seasonal variation is a considerable concern up here, I have generated 7.39 kwh so far this month due to snow on the panels, an amount that would equate to a very dark rainy day in June. Without seasonal energy storage solar PV will only have limited success up here on a large scale.

I spent some time up in Whitehorse, Yukon working on their LNG fueled powerplant. Whitehorse's electricity primarily comes from a hydro-electric dam, supplemented by LNG and diesel generators in the winter, when river flows drop and demand increases. It's a very intriguing site with the dam and generators housed on one site. I was also amazed at the amount of solar PV installed within the city, which turns out was installed due to large rebates from the utility and the government. Solar PV was definitely a sore spot with the utility workers, they even brought me over to the dam to show the surplus water being spilled around the dam, at the same time purchasing power from solar PV at inflated prices. There was belief within the utility that if that rebate money had been used to upgrade the reciprocating engine powered generators, the net CO2 reduction benefit and $/kwh reduction would have been much greater, as the extra energy for solar PV is not needed in the summer.

 

[CaptSpiff]

Here (Long island NY) it used to be that there was a reconciliation date once a year. I.e. if at that date the meter was negative with respect to the reading a year ago, one would get paid the power generation cost of the kWhs.
When I had my panels installed (2018), the reconciliation date had been cancelled. Meaning my meter continues to go backwards year after year for 15 or 20 years as I overdimensioned my array in expectation of an AC system - which turned out to be far more efficient than I had expected).

So maybe I need to get myself a phev (or use my minisplit more in winter - but I like using the BK so much...)

Yup,... you can be an early adopter, or you can wait a few more years when the selection of new Electric Vehicles is greater and the price has come way down.
I think waiting for you is the winning strategy, just like waiting on roof top PV got you an array at a fraction of the cost the early PV adopters paid.

The termination of the reconciliation date is another "win for waiting".
The old rules with Net metering meant the value of your avoided costs were about 21 cents for every kwh your PV system sent back into the grid. On Long Island we pay about:
9 cents/kwh for the energy or power product (made by generators not owned by the Utility)
10 cents/kwh for cost of transmission & distribution (poles, wires, transformers and the Utility workers)
2 cents/kwh for taxes and energy incentive programs (mostly collected and managed by the govt)
After one year, as you describe, the Utility would true up the reading and determine if you have any overproduction (banked credits) remaining. Any kwh remaining would be paid out to you at the 9 cents (it might even be less), and you just lost 11 cents of value. The logic for the Utility is that they buy power from generators for their customers as a pass-thru (ie almost no markup), and your energy was energy they didn't have to buy, so they are paying you and settling up.

Now, under the "no reconciliation date" process, you get to keep all your credits for the full contract (15-20 years) at full value. Just remember to use em,.... eventually.

 

[peakbagger]

In NH, the credit stays with the meter so if someone sells the house with the credit the new homeowner gets it.

 

[Brian26]

Been some awesome production the last few days here with the cold and clear skies. Yesterday my 5.4 kw system was clipping and hitting its 5.0 kw limit like crazy. My Solaredge SE5000 inveter starts clipping production at 5 kw.

March is off to a good start with almost 3 30 kwh days in a row. Looks clear, cold and sunny the next couple days as well.

 

[Solarguy3500]

Been some awesome production the last few days here with the cold and clear skies. Yesterday my 5.4 kw system was clipping and hitting its 5.0 kw limit like crazy. My Solaredge SE5000 inveter starts clipping production at 5 kw.

March is off to a good start with almost 3 30 kwh days in a row. Looks clear, cold and sunny the next couple days as well.

View attachment 275855

Yeah, I'm getting some pretty good clipping here the last few days with my 15.2 kW on E-W garage roofs on a SolarEdge SE10000. 68 kWh for a day in early March. I'll take it.


@Brian26 your power curve looks like you could possibly have a high AC voltage tripping situation going on. Usually, with clipping the curve just flattens at the top, but yours look like the spikes are actually dropping out, like I've seen in some cases where the utility voltage goes too high and the inverter trips out on high voltage limit, then starts back up and repeats. Is it just the monitoring platform, or do you think you might have a high voltage situation?

We have had a few customers where we have had to have the utility come out and dial down the voltage on their transformer because it was out of spec and they are required to provide voltage in a certain range.

 

[CaptSpiff]

...... Is it just the monitoring platform, or do you think you might have a high voltage situation?

We have had a few customers where we have had to have the utility come out and dial down the voltage on their transformer because it was out of spec and they are required to provide voltage in a certain range.

At what voltage levels are you seeing the inverter beginning to shut down ?

 

[peakbagger]

@Brian26 your power curve looks like you could possibly have a high AC voltage tripping situation going on. Usually, with clipping the curve just flattens at the top, but yours look like the spikes are actually dropping out, like I've seen in some cases where the utility voltage goes too high and the inverter trips out on high voltage limit, then starts back up and repeats. Is it just the monitoring platform, or do you think you might have a high voltage situation?

We have had a few customers where we have had to have the utility come out and dial down the voltage on their transformer because it was out of spec and they are required to provide voltage in a certain range.

I agree that spiky curve does not look right. The inverter curves I see with clipping have the top of the curve cut off in relatively straight line. If it is a microinverter or optimizer system it could just be data collection issues with the gateway.

 

[Solarguy3500]

At what voltage levels are you seeing the inverter beginning to shut down ?

Max AC voltage for SE inverters is 264 VAC so if the utility voltage hits 264 the inverter trips. It often happens on days where the inverter hits peak production like we've had the last few days.

I've seen this a few times where a customer is out near the end of a utility circuit, and the utility dials up the voltage on the transformer to compensate for losses near the end of the line. But I have seen it in other cases too, sometimes when the transformer is a very long distance from the inverter, such as where the house is set very far back from the road and the transformer is on a pole at the road.

 

[jetsam]

It was my first full year with the solar array. 7kw of LG panels with Enphase microinverters.

The house came with oil fired heat and DHW. For 2020 we burned 0 gallons of oil (because I heated with wood, and went to a heat pump water heater).

Next projects are to add minisplits and an electric boiler to replace the old shut down oil boiler so we can run that when we go out of town!

 

[Solarguy3500]

Well, my inverter quit yesterday morning. I happened to look at my energy monitoring app around 10 in the morning and it showed 0 production. It had produced 4.7 kWh earlier that morning, but stopped producing around 9:15. I connected up to the inverter with the app on my phone that we use to commission the newer SolarEdge inverters that don't have an LCD screen anymore. It pushed through a firmware update, and I hoped that would fix it, but no luck. Powercycled it a couple times but it's dead.

It was killing me knowing that my solar was producing 0 today on a perfectly clear, cold, sunny day without a cloud in the sky.

 

[andym]

Well, my inverter quit yesterday morning. I happened to look at my energy monitoring app around 10 in the morning and it showed 0 production. It had produced 4.7 kWh earlier that morning, but stopped producing around 9:15. I connected up to the inverter with the app on my phone that we use to commission the newer SolarEdge inverters that don't have an LCD screen anymore. It pushed through a firmware update, and I hoped that would fix it, but no luck. Powercycled it a couple times but it's dead.

It was killing me knowing that my solar was producing 0 today on a perfectly clear, cold, sunny day without a cloud in the sky.

How old was the inverter? I am beginning to kick around the idea of putting in a grid tie system in a year or two and have been reading some about what's involved. Would this be a situation where having 2 inverters is an advantage?

 

[Solarguy3500]

How old was the inverter? I am beginning to kick around the idea of putting in a grid tie system in a year or two and have been reading some about what's involved. Would this be a situation where having 2 inverters is an advantage?

The inverter is almost exactly 1 year old.

Yes, it is true that if you had (2) 5kW inverters instead of (1) 10kW inverter, if one broke you would still have half of the system producing. I just decided to roll the dice with 1 and looks like I'm going to have a bit of down time. Microinverters also avoid the single point of failure problem. If one micro fails, you still have the rest of the system working. The old M series Enphase micros were notorious for failing, but the new IQ series seem to be much more robust.

 

[ABMax24]

How old was the inverter? I am beginning to kick around the idea of putting in a grid tie system in a year or two and have been reading some about what's involved. Would this be a situation where having 2 inverters is an advantage?

I wouldn't get too caught up in that thought. Twice as many inverters could fail twice as often, which in theory would still be the same amount of lost production if it takes the same amount of time to replace. The only difference would be you are paying for twice as many service calls to have the inverters replaced.

 

[peakbagger]

I have 6 inverters, 4 used Enphase microinverters to keep my 4 panel original 660 watt array running (the original string inverter was 20 years old), a 14 year old 2 KW String inverter for my pole mount (it got zapped by the utility early in its life and I got a rebuilt one on warranty), and a 3KW string inverter that is around 9 years old. I did pick up a 6KW dual MPPT string hybrid inverter as a spare. Its made by Delta but was labeled Solar City. Its DC couple design for a battery the Tesla no longer sells but for $600, it will work as backup grid tied unit. If one of the string inverter dies, I will probably just install the Delta and tie the arrays into different MPPT channels.

Solaredge units seem to have a lot of issues., but if just may be that they are quite popular as they are a less expensive Rapid Shutdown solution with optimizers than microinverters. The optimizers also seem to hold up longer when baked under a panel on a roof compared to microinverter. The inverters seem to be "fragile" and they seem to have a lot of software update issues. I guess that comes from being on the "bleeding edge".

I am an advocate of oversizing inverters. Its common sense to me that electronics will work better when not running at or near 100% load. Installers and manufacturers always oversize the arrays attached inverter which causes clipping. That said 1 one year old Solar Edge string inverter failing is either a utility zap or manufacturing defect. If you don't have one, a high quality surge protector like a Midnight Solar SPD on the main electrical panel or on the inverter circuit will substantially reduce any potential for power zaps. Cheap surge suppressors like the Delta can type will keep your wiring from smoking but their clamp voltage is too high to protect electronics. I learned that lesson on my 2KW unit but luckily it was under warranty. Its a Fronius and they had a replacement to me in 5 days. I dont do any data reporting so it was plug and play and no dealer to mess with, I just called Fronius and they shipped me one.

 

[jebatty]

Our 12.3 kW system has 46 panels, 26-265 W panels installed in Oct 2013 and then added 20-270W panels in April 2015. All have Aurora Power One micro-inverters, each micro having its own internal optimizer. Two micros in the 2013 system have failed, one early on and the second last summer. Both were replaced under warranty. I also purchased a couple extra micros just in case Aurora did not stay in business, which has happened but tech and warranty support have remained available. Tech support has been excellent. Switching out a failed micro takes about 10 minutes. As a ground mount system all that is needed is a screw driver and a step ladder. Ground mount also helps keep the micros cool. The system has functioned well, including at temps as low as the low -30'sF and high temps into the high 90'sF.

I suppose I have 46 inverter fail points, but a failure affects only one panel, not the whole system or string.

Edit add: the micros are rated at 250W but have functioned up to 260W before any clipping has occurred.

 

[Solarguy3500]

I am an advocate of oversizing inverters. Its common sense to me that electronics will work better when not running at or near 100% load. Installers and manufacturers always oversize the arrays attached inverter which causes clipping.

From a functionality standpoint I would tend to agree. I would also agree that it is common to overdrive inverters.

To add a little context as to why overdriving inverters is so common in MA: It has a lot to do with the way the net metering legislation is written here. There is a net metering cap system which applies to systems over 10 kW AC (so the rating of the inverter) in which anything larger than a 10 kW AC system takes a 40% hit on the value of net metering credits (60% of retail rate) while there is an exemption for systems 10 kW or less which receive full retail for net metering credits, and don't have to apply for net metering cap space. Further complicating things, the net metering caps are full in some utilities territories. So, the end result is most installers, myself included, end up overdriving a 10 kW inverter to maximize production and stay within the 10 kW limit.

 

[Brian26]

Yeah, I'm getting some pretty good clipping here the last few days with my 15.2 kW on E-W garage roofs on a SolarEdge SE10000. 68 kWh for a day in early March. I'll take it.
View attachment 275860

@Brian26 your power curve looks like you could possibly have a high AC voltage tripping situation going on. Usually, with clipping the curve just flattens at the top, but yours look like the spikes are actually dropping out, like I've seen in some cases where the utility voltage goes too high and the inverter trips out on high voltage limit, then starts back up and repeats. Is it just the monitoring platform, or do you think you might have a high voltage situation?

We have had a few customers where we have had to have the utility come out and dial down the voltage on their transformer because it was out of spec and they are required to provide voltage in a certain range.

I use an aftermarket Efergy electricity monitor. It has a 15 second data refresh rate and the graph was 1 min intervals. It turned out there were some scattered clouds that day. I did notice that sometimes scattered clouds cause it to clip more. Wonder if the sunlight is increased briefly by the clouds?

This April will be 4 years on my SE 5000 inverter and 20 optimizers with zero issues.

 

[peakbagger]

Yes scattered clouds create something called the edge effect. When the sun just transitioning into or out of the cloud there is brief spike in irradiance. The exact physics is beyond me but I think of it as the equivalent of briefly flashing at mirror at the panel