learn me solar for your house

The sarcastic side of me says, if you want to find out about residential solar, just spend a Saturday at my house.  Chances are good, someone will be stopping by with a very environmentally friendly company name, and an official looking polo shirt to explain it to you.  Their English comprehension skills are great up until the point, where you say, No Thank You, and that's generally where the grasp of the language seems to break down :-)

My current work project is targeting about 2.5 megawatt of roof top solar capacity.  Doing this large of a roof top array is new ground for me.  Most of our clients are not willing to invest that kind of money.

I'm not a seller, but if it counts, you can make the number 1 for people who would do it again. I live in a moderate climate in CA, put 6.2 kw on my roof, and even bought the damn battery. I like all of it. Grid goes down for a few minutes or hours, or even a couple days and my power is seamless. I purchased outright which wasn't smart from an opportunity cost standpoint, but feels good in a - 'if I need to sell' kind of way. It was $27k and then I think 30% federal rebate at the time, so roughly 19k out the door. We are net zero over the year and have a similar scheme to Keith in CO. Only thing I don't like is biannually cleaning them. I'd love to build a house with solar in mind from the start, or have a building like Keith that doesn't appear to be anywhere near any trees and such. My payback will be ~8.5 years if electricity prices stay at 2018 levels. 
 

I may not understand what you are getting at with someone looking at it 'like a pool'. You buy the house with solar. It's an appliance that pays you back. Makes electricity at a much more fixed rate than any provider sells it to you. 

Pools are neutral when it comes to house values, they don't add any value but don't seem to have a negative effect either. That was the comparison. 

I have a small install that covered about half our house needs before getting an EV, a 3.6 Kw system. We did a smaller system because unlike Keith, our utility (DTE) pays us only about half the value of each watt generated over our needs, so it's better to use the power as you make it than sell it to the grid. DTE is actually asking to pay almost nothing to solar owners and add a surcharge based on peak usage throughout the year that might be $100 a month (doubt it will get approved however)

Basically utilities are constantly fighting to take money away from solar owners, and expect that to continue.

Even with the poor deal with DTE I expect to be revenue net positive in a decade. I expect the system to last at least 25 years (that's the minimum warranty for generating like 80% of installed power). That said, efficiency gains from better building envelope sealing and insulation are a better ROI. Depending on area you're selling in, I'd expect solar to have a slight benefit for your value of home but not huge. 

I would NOT do one of the lease your roof deals, because of trouble if you had to sell the home. We bought outright but there are also low interest loans available.  Best to do it at the same time you install a new roof - you don't want to be replacing a roof 5 years after the panels go up. Batteries are maybe worth it if you want a whole home generator, power is expensive where you are, and you have a large system capable of handling all your electricity needs. But they only last ~10 years or so. 

Some utilities have mandates to hit a minimum amount of renewable energy, so they're pro solar. This is particularly true in Colorado: https://www.energy.gov/eere/geothermal/articles/colorado-boosts-its-renewable-energy-requirement-30-2020

One fun thing - we turned our array on before the net meter was installed due to paperwork problems. At the time, we had an old-school dial meter. It was literally running backwards during the day :) That effectively gave us net metering over the course of the month, but I don't think that would have worked during the summer when we produced more than we used. I suspect the utility would have been a little cranky about a negative reading.

Erich- they are trying the same thing in my area of CA. ~$80 surcharge on top of paying us wholesale rates for any overage. I'm on the 'true up' programs wherein once a year we take the annual total and subtract out what we made and then 'true up' the bill. I'd like to get an electric car to make sure I don't send any of it back to the grid. 

In reply to dyintorace :

Your most expensive in the state is a fraction of what I pay in CA. I'm at $.28 for tier 1 and .35 for tier 2. Our tiers are also much smaller (355kWh for tier 1) and it's not hard to end up in tier 4 in the summer. 

What happens if a single solar panel goes bad , like if  something dropped on it  or it shorts out?

are they hooked up in series or parallel?

do they all need to have a certain amount of sun , say later in the day half are in the shade because of a tree ?
and how long before panels  are no longer good , I see used ones sometimes on Craigslist ?

thanks for your ideas

Assuming my panels are representative of modern ones, they all have their own microinverters attached and are all independent. A bad panel will stop producing but will not take out the whole array. 

For the same reason, shade over part of the array will downgrade the efficiency of those panels but not the ones still in full sun. Newer panels are apparently less affected by partial shade than older ones, which would basically stop working if a corner of them was shaded. You can definitely see the efficiency of the array change with the angle of the sun.

Based on my conversations with pros, panels don't so much go bad as just become less and less efficient as they degrade. That just means you need more of them for the same output.

In reply to californiamilleghia :

It depends on the inverter type. With old style string inverters, a bad or shaded panel could drop production of the whole string. Not allowed in CA anymore due to ground level shutdown requirements. String inverters now work with rooftop mounted optimizers, which handle shading and outages much better. Or you have micro inverters, which treat each individual module like it's own system. Pricing is pretty close, very slightly more for the micros. String + optimizers slightly better for the installer, micros slightly better for the homeowner or especially homeowner doing their own install. The difference being installers don't like going back to jobs for warranty work. Wall mounted string inverters have around a 10 year life. Plan on replacing a couple times during the life of the system. But it's on the wall, easy for the installer to swap out, and usually pretty trouble free during the warranty period. Micros are installed on the roof under the modules. They are usually 25 year, should last the life of the system. But if one goes bad, the installer needs to go up on the roof to change it. And there are a lot more of them, so lots more potential failure points. On the homeowner side, it's a different deal. If a string inverter goes down, the system goes down until it's replaced. If a micro goes down, you just lose that panel until it's replaced. Much better for the homeowner, but potentially a lot more warranty calls for the installer. That said, they are both reliable. 

I just had the wife pull ours from last month....ouch

This is the basic do your research from BC Hydro the utility for most of BC https://www.bchydro.com/powersmart/residential/building-and-renovating/switch-to-solar-energy.html 

In reply to Boost_Crazy :

wow I thought DTE was bad at 0.17!

Boost_Crazy said:

In reply to dyintorace :

Your most expensive in the state is a fraction of what I pay in CA. I'm at $.28 for tier 1 and .35 for tier 2. Our tiers are also much smaller (355kWh for tier 1) and it's not hard to end up in tier 4 in the summer. 

 

That's totally insane!

Boost_Crazy said:

In reply to californiamilleghia :

It depends on the inverter type. With old style string inverters, a bad or shaded panel could drop production of the whole string. Not allowed in CA anymore due to ground level shutdown requirements. String inverters now work with rooftop mounted optimizers, which handle shading and outages much better. Or you have micro inverters, which treat each individual module like it's own system. Pricing is pretty close, very slightly more for the micros. String + optimizers slightly better for the installer, micros slightly better for the homeowner or especially homeowner doing their own install. The difference being installers don't like going back to jobs for warranty work. Wall mounted string inverters have around a 10 year life. Plan on replacing a couple times during the life of the system. But it's on the wall, easy for the installer to swap out, and usually pretty trouble free during the warranty period. Micros are installed on the roof under the modules. They are usually 25 year, should last the life of the system. But if one goes bad, the installer needs to go up on the roof to change it. And there are a lot more of them, so lots more potential failure points. On the homeowner side, it's a different deal. If a string inverter goes down, the system goes down until it's replaced. If a micro goes down, you just lose that panel until it's replaced. Much better for the homeowner, but potentially a lot more warranty calls for the installer. That said, they are both reliable. 

BTW, I just tapped into the data stream coming off my array. It's interesting to see and is going to spark a bunch of learning on my behalf, such as what reactive power implies. But because of the microinverters, I can see the real-time and lifetime output of every panel. It'll make it easy to see if one is underperforming. I can see some variance although some of that is going to be how fast snow melts off the panels, for example. I just need to figure out which panel is which, "Inverter E00122136049218" is not helping. Also, I can see how much power the array consumes on its own.

Interestingly, all the quotes I got were for micros. Nobody suggested a string setup. I do know the array at Flyin' Miata is on the second set of inverters after...12 years?

dyintorace said:

Boost_Crazy said:

In reply to dyintorace :

Your most expensive in the state is a fraction of what I pay in CA. I'm at $.28 for tier 1 and .35 for tier 2. Our tiers are also much smaller (355kWh for tier 1) and it's not hard to end up in tier 4 in the summer. 

 

That's totally insane!

I just pulled up our largest bill from last year........$0.11 per kwh. 

2034 kwh @ $226.40 (this is when the AC is running 22 hours a day in an 1815 sq ft house. 

Energy is so cheap here, that's why even though I'd like solar to make me feel good........the economics just don't work out. And because of the gas water heater/furnace, 6-7 months out of the year we don't break 750 kwh.

I'd install the panels when your furnace quits and you replace it with minisplits, but not earlier.

In reply to Keith Tanner :

BTW, I just tapped into the data stream coming off my array. It's interesting to see and is going to spark a bunch of learning on my behalf, such as what reactive power implies. But because of the microinverters, I can see the real-time and lifetime output of every panel. It'll make it easy to see if one is underperforming. I can see some variance although some of that is going to be how fast snow melts off the panels, for example. I just need to figure out which panel is which, "Inverter E00122136049218" is not helping. Also, I can see how much power the array consumes on its own.

Interestingly, all the quotes I got were for micros. Nobody suggested a string setup. I do know the array at Flyin' Miata is on the second set of inverters after...12 years?
 

I prefer micros too, but they do have a downside for large installers. Interestingly, they used to limit the data visible to the homeowner. Lots of call backs to the installer when they saw variances, so they changed the reporting to overall system and faults only. Kind of like non 1994 Miata oil pressure gauges. They had to dumb down the reporting to limit excessive calls. 

In reply to z31maniac :

We are around .13/kWh. We have had $450 electric bills before. Worse was when the well switch stuck on for a week solid. That was over $500

Yeah, the canned info is very pretty and heavily consolidated. It's a useful level of detail for an average homeowner who just wants to see "ooo, look, I'm making power". The oil pressure gauge comparison is apt :)

I can certainly understand why you'd want to gloss over individual variances. For example, the data tells me both current (har har) and lifetime production of a panel. When I looked this morning, a small handful of panels were only at 50% of the others. But their lifetime production is in line, so I'm going to assume they were just a little slower to wake up. I'm curious as to how they interact and behave, and I'll only contact my installer if I find one that's behaving radically differently from the others. 

It's been fascinating learning how they react and how the sun moves across our property. My nerd self is very much enjoy.

In reply to Keith Tanner :

Do you have any instructions on how did you set that monitoring up? I think I have the same panels as you and I find the Sunpower app lacking.

I have concerns about solar power, I am researching Geothermal. Former employer had Geothermal that seemed to work well, I think it was Dandelion. Regardless if you spend $2100 per year on heating and cooling, factor that it takes 15-20 years to payoff the alternative energy. Do you factor in the potential increase in value of your home? or would it be moot point because the more people that sign up for alternative energy the less value it would add.

In reply to Erich :

There are two steps: accessing the information, which is fairly easily done using something like a Pi Zero. That's also something I'm familiar with so it didn't take long at all. It gets you raw data that you can poke through.

 Second step is putting it into a format you can use, and most of the guides involve Home Assistant. This is a whole lot messier with custom repositories and the like. It has the potential for pretty graphs but I think HA is not an easy toy and is a hobby unto itself for some people. I ended up parsing the data myself to dig out what I wanted.

For example, I found that one panel is 16% below the average for lifetime production, so I'll be watching it relative to the others. Maybe it's the last one to melt off a snow cover or it's the one panel that gets shaded by a tree at very low winter sun angles, which means it should run at about the same level from now on. Or maybe it's a weakling, in which case I'll be calling my installer :) Right now, it's slightly above the array average.

For resources, this is probably the most polished option and contains links to others: https://starreveld.com/PVS6%20Access%20and%20API.pdf 

In reply to Keith Tanner :

I figured it was with Home Assistant. That's way beyond my abilities unless I want to spend hours learning it. 

In reply to Erich :

The first step is reasonably accessible if you follow the cookbook in the PDF. That lets you see things like instantaneous output for the array and each individual panel as well as lifetime production by simply hitting a specific page in a browser. Also temperature, which I am going to find interesting. It just doesn't do any logging.

Home Assistant is a whole different level of messing about.