Going solar

General conversations about BMW E28s and the people who own them.
Mike W.
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Re: Going solar

Post by Mike W. »

DonaldHopkins wrote:Solar power is in great demand and around one in four homes already has it in regional. If you decide to sell or rent out your home or business premises, a solar photovoltaic (PV) system is a popular feature and may add market value.
Regional is the key. A buddy of mine is in Arizona, near Phoenix, so lots of sun. Perfect for solar right? Apparently not so fast. The local power company, which does provide power at less than half what I pay, jacks up your rates to the max if they detect solar in use. So nobody down there has it.
south26
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Re: Going solar

Post by south26 »

Well last month the electric bill was 33 dollars. So very happy with panels even with it being the dark and gloomy season. The lowest I can get it down is 12 dollars, since that is all of the fees.

Andy
Jeremy
Beamter
Beamter
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Re: Going solar

Post by Jeremy »

Mike W. wrote:Just signed the contract. One huge selling point for the particular contractor/parts, is it's capable of 2Kw of off grid power. Significant to those of us living in PGE supplied areas.
Does the system you picked supply power when it loses connection to the grid? In a horrible sort of irony, most PV systems stop working when the power goes out to avoid backfeeding the power grid inappropriately. I don't know exactly what you need to avoid this, but I know that most systems installed do not include off grid capabilities.
south26
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Re: Going solar

Post by south26 »

Jeremy wrote:
Mike W. wrote:Just signed the contract. One huge selling point for the particular contractor/parts, is it's capable of 2Kw of off grid power. Significant to those of us living in PGE supplied areas.
Does the system you picked supply power when it loses connection to the grid? In a horrible sort of irony, most PV systems stop working when the power goes out to avoid backfeeding the power grid inappropriately. I don't know exactly what you need to avoid this, but I know that most systems installed do not include off grid capabilities.

Yes my system dies when the grid goes down. We would have to have bought a 14 thousand dollar battery to have it work off grid. Was told by the seller. If you want that buy a generator.

Andy
Mike W.
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Re: Going solar

Post by Mike W. »

Jeremy wrote:
Mike W. wrote:Just signed the contract. One huge selling point for the particular contractor/parts, is it's capable of 2Kw of off grid power. Significant to those of us living in PGE supplied areas.
Does the system you picked supply power when it loses connection to the grid? In a horrible sort of irony, most PV systems stop working when the power goes out to avoid backfeeding the power grid inappropriately. I don't know exactly what you need to avoid this, but I know that most systems installed do not include off grid capabilities.
This particular inverter is supposed to supply up to 2Kw in the event of a power outage, assuming good sun and all that. It was a huge selling point to me especially with the blackouts we've had recently. The cut sheet does list that too, but nobody besides the guy I signed a contract with seems to know it. Another contractor I interviewed was highly skeptical, but at the same time guessed the brand.

However one issue he's having is the high starting loads on things like big refrigerators, which I have, it might be only 500 watts to run, but starting can be up to 6X that on motors. He thinks he's got a fix, a soft start I'm guessing, but is waiting to do the install until he figures it out for sure. Meanwhile the clock is ticking on the 30% tax credit. :cry:
Jeremy
Beamter
Beamter
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Re: Going solar

Post by Jeremy »

Mike W. wrote:However one issue he's having is the high starting loads on things like big refrigerators, which I have, it might be only 500 watts to run, but starting can be up to 6X that on motors. He thinks he's got a fix, a soft start I'm guessing, but is waiting to do the install until he figures it out for sure. Meanwhile the clock is ticking on the 30% tax credit. :cry:
First: I'm far from an expert on any of this.

However, when investigating backup power for my house I was told by several sources to count on double the running load for well pump startup. I can't imagine that a 500 watt fridge pulls 3k watts on start. That'd require either 240V at 12.5 amps per fridge or 120V at 25 amps per fridge. Is that really how they're wired? 6x the running amps to start up sounds like an excessive estimate to me.

I haven't wired the house or specced a generator yet though, so I can't speak from personal experience.
Mike W.
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Re: Going solar

Post by Mike W. »

Yep, induction motors draw a lot at start. I misspoke a bit, I should have said up to 6X. And that's more of an instantaneous locked rotor current, after current has been applied, but before the rotor starts to turn, not the whole time until it gets up to speed. Compressors, be they air or refrigeration are notoriously hard starters since they are often pushing against a full load. But something like a fan motor isn't as hard to start, it's only got the weight of the rotor and fan initially, it's not doing the work of pushing any air until it gets up to speed. But it's also why an inverter rated at 2Kw may not start my refrigerator which nominally draws 5 amps or 600 watts, it may be a max 2Kw, not a running with X overload factor.

First hit on LRA vs RLA,

Image
However, another, much more common instance where the motor draws Locked Rotor Amps is at start up. That is, every time a motor is started, it pulls Locked Rotor Amps for a split second. The reason is that at the moment electrical power is applied, the rotor hasn’t started to rotate yet. So, for that instant, the motor thinks the rotor is locked. Once the motor starts to turn, amperage falls to something between full load and maximum amps. Once again, this happens very quickly, in a few tenths of a second.
tn535i
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Re: Going solar

Post by tn535i »

If the current is insufficient to get a motor started it might be the motor just draws the maximum current 'available' and remains in a sort of locked rotor state. Why wouldn't they just add a bank of capacitors AFTER the inverter to supply that extra push to get motors started? Much simpler than batteries and I thought it would have been an obvious part of any off grid solar system.

Many motors in AC systems, garage door openers etc... already have small start capacitors as part of the package. I built a phase converter years ago to run an old 3-phase lathe off single phase 240 volt power and capacitors are absolutely the trick to get power consumption down and easier starting of my idler motor. The same principle should work when the inverter does not have enough guts.
Mike W.
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Re: Going solar

Post by Mike W. »

Woo Hoo. And we're making juice. :banana: Finally. Signed the contract in mid November, and there have been some complications like holidays and fires, but it took an awful long time and cost me 4% of the system cost in loss of tax credit it took so long. But 5.5Kw nominally rated system and we're running. 250W after sundown but before dark. I'll be peeking tomorrow to see what it's doing.
south26
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Re: Going solar

Post by south26 »

Yea, we have really been happy with the panels. Even on kind of cloudy days we make some power. Last month the electric was 28 dollars and 12 of that is fees.


Andy
Mike W.
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Re: Going solar

Post by Mike W. »

south26 wrote:Yea, we have really been happy with the panels. Even on kind of cloudy days we make some power. Last month the electric was 28 dollars and 12 of that is fees.


Andy
In December? Not bad, not bad indeed. I've got a bizarre usage/cost pattern, I think it's Feb and Oct that are my big consumption bills, bills, not dates, so I'm guessing Christmas lights etc and August A/C.
tn535i
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Re: Going solar

Post by tn535i »

Mike W. wrote:In December? Not bad, not bad indeed. I've got a bizarre usage/cost pattern, I think it's Feb and Oct that are my big consumption bills, bills, not dates, so I'm guessing Christmas lights etc and August A/C.
About those Christmas lights in December... My wife will NOT use LED and puts out a bunch of lights. This year she went over the top as we had an open house to raise money for a missions related thing. Maybe 10 homes participated and they raised a couple thousand dollars. I measured the current draw on the tree in the living room alone (wanted to make sure it was safe) and it was nearly 9 amps which is over 1000 watts of power and she has to have the tree on all the time and most of the rest too and especially whenever it gets dark. I figured that from Thanksgiving to New Years with all the lights we had out our electric bill went up about $100. $100 to keep all the decorations lit is better than spending money for therapy due to season depression, hah. It was worth it if I look at it that way but if I had an inverter and batteries sized for normal evening and nighttime load it would have killed it for sure.
Mike W.
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Re: Going solar

Post by Mike W. »

Hmmm. If I'm reading the inverter right, and I think I am, I generated 21Kwh today. In January. Granted it was a gorgeous winter day, sunny and warm, but that's 600Kwh a month. In the winter. And I only run 500-550 Kwh average year round. Looks like I'm going to be selling a bunch of power to PGE for $.03 a Kwh. Oh well, I didn't want to be undersized. Everyone says they don't degrade much with time, but I still want to be good, size wise, in 20 years. Oh well, we'll see.
chilone
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Re: Going solar

Post by chilone »

"Loan".
south26
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Re: Going solar

Post by south26 »

Still liking the panels. After 4 years and rising electricity rates starting to see it paying off.

Andy
davintosh
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Re: Going solar

Post by davintosh »

Just curious, what is the life expectancy of the panels on your house? Have there been any advances in that in recent years?
south26
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Re: Going solar

Post by south26 »

davintosh wrote: Mar 19, 2023 2:11 PM Just curious, what is the life expectancy of the panels on your house? Have there been any advances in that in recent years?
mine are 30 years. So 26 years left.
Mike W.
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Re: Going solar

Post by Mike W. »

davintosh wrote: Mar 19, 2023 2:11 PM Just curious, what is the life expectancy of the panels on your house? Have there been any advances in that in recent years?
Everybody says they don't degrade, but nothing lasts forever, if only due to obsolescence. I'm not keeping up on it, but in the time between I signed the contract and the time they were installed there were 2 increases in panel output. Not much, but minor increases. No telling how much more in 3 years.

I'm not tracking annual sun hours or anything, but my system has gone up in output, less than 1%, both years above the year before. I'm liking that trend. I do track the output pretty much daily.
vinceg101
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Re: Going solar

Post by vinceg101 »

south26 wrote: Mar 19, 2023 3:47 PM
davintosh wrote: Mar 19, 2023 2:11 PM Just curious, what is the life expectancy of the panels on your house? Have there been any advances in that in recent years?
mine are 30 years. So 26 years left.
I guess location and environment have a lot to do with (along with manufacturer). In designing an off-grid 66.5KW project here in SoCal, the PV consultant and panel manufacturer quoted panel lifespans of 20-25 years on average for our application. The Micorgrid battery & Inverter were even less (around 15-20 years). Both carry pretty big price tags which needed to be factored into energy costs.
gadget73
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Re: Going solar

Post by gadget73 »

davintosh wrote: Mar 19, 2023 2:11 PM Just curious, what is the life expectancy of the panels on your house? Have there been any advances in that in recent years?
without going to look at the paperwork I want to say mine are supposed to output at least 80% of new power after 25 years.

Yes they do degrade but its a relatively small amount per year.
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