Clean Solar Panels!

[RJSakowski]

We live in mid-Michigan; our solar set up has 26 panels rated at 380W (22 of them) and 370W (4 of them) for about 9500W max output. We see some pollen, dust and dirt on the panels, but they get cleaned pretty well when it rains. Our biggest issue is snow. I've looked at our output in the morning after a snowstorm and see (for example) 0.50kW of generation. We have a floor broom with a very-extended handle; broom off the snow and our output goes up by 4X - 6X.

View attachment 480047

We're North of you with a ground-mount system instead of room mount. The rule of thumb for panel inclination angle is to set them at your latitude. We're at 43 deg.; our panels are at that angle and clean off pretty easily. I guess you could do a bit of an experiment and purposely roll out some window screen or something to simulate dust/dirt and see how it affects your output. Our system uses a Generac invertor. They have a nice app that gives us lots of live data.

There are many sources for solar panel brushes/squeegees. I see them running from $200 - $600.

View attachment 480050

And on the "is it worth it" topic, it depends on your motivation. In our case, our power company charges $0.126/kWh and gives us $0.056/kWh if we send power back up the pole. We also have a $30/month service fee regardless of usage. In 2023, we generated 12.2 MWh of solar, we drew 0.277 MWh off the grid, and our house drew 10.6 MWh. We also have 18kWh of battery backup so the math isn't so simple (12.2 MWh + 0.277 MWh doesn't equal 10.6 MWh). Our accumulative electric bill for 2023 was under $400, before we added the solar it was ~$2100.

Our system ran around $40K after the 30% federal tax credit. If we saved $2000 a year it'd be a 20-year payback assuming no gain on the initial $40K investment. We will not see a net payback within my wife and my lifetime. But our motivation was to get a little greener, and give us (albeit limited) power backup during an outage. Having a bit of OCD, for backup we have what I term as "summer mode" and "winter mode". Summer mode is running refrigeration, winter mode is running the furnace.

Long story longer, we had a big windstorm in late-August 2023 that took out the power. The batteries kicked in instantly; TV in the kitchen didn't even flicker. Our 18kWh of backup is limited, the transfer box only switches 4 circuits (we power our well, kitchen frig, internet(for Generac) and our propane furnace). We have 2 small freezers which I ran extension cords to, plus our router. We were drawing about 300 W/hr. with that load on the system. On a sunny day, we'll make >60 kWh; no issue charging the 18 kWh batteries and absorbing ~7 kWh of normal daily house "the power is out" draw. However, we've made as little as 1.6 kWh in a day; our worse 5-day total has been 12 kWh. We'd be in trouble during the summer as we'd lose the batteries after 3-4 days IF we had the two freezers and frigs running and crappy solar.

In the winter, I'd hand-truck the two freezers outside and let Mother Nature take care of them. Our major draw is the propane furnace which uses 350W when it's running. Daily draw would be around 3 kWh, so winter back up mode with crappy solar is about 4-5 days. To us, it's nice to have the limited power backup though a Generac propane bypass generator would have run a lot less than the solar set up.

Bruce

Thanks for the detailed analysis..

I have been interested in solar electric generation for more than fifty years. costs have come down significantly but are still not in the cards for us. We line in a valley where the sun rises above the tree line and hour after sunrise and sets no later than 5 PM summer or winter. I've run the numbers and payback would exceed my expected lifetime.

In Wisconsin, there is this industry which has sprung up installing solar systems at no cost. They use the government subsidy for the down payment and essentially promise that the monthly savings in electrical bills will offset the monthly pay down on the loan for the system. My wife saw an add on line and gave them a call. The sale guy was extolling the benefits of owning solar and after about 20 minutes, I asked to speak to him. I explained our situation and further stated that because of to high and steep roof and its location near the tree line to the west, any system would have to be ground based. Also because of the shortened duty cycle, the system would have to be increased by some 20 - 30%. We agreed that we were not a candidate for solar.

My neighbor across the road has had solar for more than fifteen years. She lives atop the hill and has full sun from sunrise to sunset. Her initial system is ground based and tracks the sun. When the system was installed, the utility company had a very generous credit where she actually got higher than retail cost for her excess generation so she essentially had zero cost to the utility. She has since doubled the size of her solar system, this time with a fixed ground based array. She also acquired an electric vehicle with the intent of generating essentially all of the residential and vehicular energy needs with her solar system. I haven't asked her lately how that's working for her. She has had just over a year now on her new plan.

Our monthly usage runs between 1,000 and 1,800 kwh at a cost of $.13/kwh for an annual cost of around $2,000. Even if we generated all our electrical needs, it is unlikely that we would see a payback in my lifetime. (At 80 y.o., any warranties more than 20 years are a lifetime warranty)

One thought that I had regarding making solar generation more effective was to add outboard reflectors to concentrate the light. I don't know how much amplification the panels can handle but it would should be a good way to make up for the limited exposure time. A tracking system would also increase efficiency.

 

[projectnut]

I decided to go with one of these for backup power. It should be large enough to power everything I need to use. It's a mere 3273 hp and puts out 2250 KW.

Rebuilt CAT 3516CHD Generator Set – T4i ‣ React Power Solutions

#post_titleRebuilt CAT 3516CHD Generator Set; 2010 Model - 0 Hours Since Major Overhaul; 2250kW Prime Power; 480/277V; Open Skid Mounted; EMCP 4.2 Control Panel; Tier 4i Emissions; Clean Emissions Module; In Stock - Ready to Ship

www.reactpower.com

 

[Janderso]

Rainbow vacuum cleaner.

Ha, I haven't thought of that for a while. Just thinking of the dirt filled bubbles bursting

 

[Smithdoor]

When the "Solar Guys" knocked at my door I am pretty sure one of them was on my door step a month prior trying to sell me a Rainbow vacuum cleaner.

I am sorry, the whole solar industry and all of their promises just smell like a scam to me. When I was a kid solar hot water was the "in thing". What happened to that? I think if the solar industry actually told the truth instead of a bunch B.S. sales promises nobody would actually buy a system. I have heard of people having a hard time selling their house because of long term commitments with solar providers. I have also heard of home buyers getting screwed by the commitments to solar providers because they failed to read the fine print when buying a house. I have also heard that the energy generated from the panels diminishes over time necessitating panel replacement to remain viable. From everything I have heard the actual savings fall very short of the sales promises.

Unfortunately most electric utilities are for profit companies. As such they are going to extract their pound of flesh from you if you are connected to their system whether or not you have solar panels. Their only motive is profit!

The materials for solar cost about $5,000.00 and labor for 3 day 2 guys working very slowly the cost is $25,000.00

Sounds like great work.
They good to putting panels on north sloping away from sun light.

Dave

 

[matthewsx]

My father-in-law is an engineer who designed his up-north Michigan home 40 years ago with the intention of adding solar. He never did it.

When he has calculated the pay back time it’s never been enough to justify doing it for him. He can tell you how he calculated the perfect angle for producing maximum output, what kinds of technology was available each time he ran the numbers, what trees he cut down to optimize sunlight on the roof, etc, etc, etc….

But my question is why not do it anyway if you believed in it enough to base your original design on it, and you can afford it anyway?

If you love your children, grandchildren and great-grandchildren go ahead and do it for them regardless of the payback time.

As long as it doesn’t cut too much into the tool budget it’s a win for everyone.

JMHO,

John

 

[Smithdoor]

My father-in-law is an engineer who designed his up-north Michigan home 40 years ago with the intention of adding solar. He never did it.

When he has calculated the pay back time it’s never been enough to justify doing it for him. He can tell you how he calculated the perfect angle for producing maximum output, what kinds of technology was available each time he ran the numbers, what trees he cut down to optimize sunlight on the roof, etc, etc, etc….

But my question is why not do it anyway if you believed in it enough to base your original design on it, and you can afford it anyway?

If you love your children, grandchildren and great-grandchildren go ahead and do it for them regardless of the payback time.

As long as it doesn’t cut too much into the tool budget it’s a win for everyone.

JMHO,

John

Solar steam is best .
It use technology from the Titanic.
The number three engine runs at 180°F steam and vacuum.
The battery is hot water under 212°F. No pressure tank since it is at 212 and on other side is a vacuum.

Dave

 

[ACHiPo]

A quick story.
Three years ago, my wife and a friend, who owns a solar company, finally talked me into buying a system.
We were told the panels never need cleaning?

Our “true-up” last year was $75. This year it was $1,200!!!. Our electrical source is PG&E, the most corrupt and expensive municipality in the country. They own the PUC.

I had a study done )no charge) by the company we purchased from. They said there are two main factors causing the reduction in production.
Dirty panels and/or excessive shade from a neighbors oak tree. Well, the tree was there last year and the panels are very dirty.

I think it was a sales pitch, no cleaning, no mess, no fuss.

The pic shows the upper clean panels and the lower dirty panels. This was after a three inch rain a few days ago!!

He uses <20 ppm water filtered through a Reverse Osmosis system on his truck. $166 per visit. I signed up for twice a year cleaning. Hopefully it will be worth it.

Any thoughts?

Jeff,
I saw about a 10% efficiency increase the first time I cleaned our solar panels. I have our window cleaners do it every year for an extra $100.
Evan

 

[ACHiPo]

I'm not sold on solar panels or wind generators. Everyone I know around here that has tried either method has spent a ton of money on their system with little or no return on investment. The panels get covered with snow and ice in the winter months, in the spring they're covered with seeds, and in the fall they're covered with leaves. When they fail parts are either impossible or hard to get. When they are available they're so expensive they totally negate any savings generated by the electricity they produce.

The same is true of wind generators. Anything over 5 years old is so antiquated there are no parts available. In most cases the manufacturers have gone out of business.

As long as I'm on a tangent I'll also include comments on the electric busses the city has purchased. Over the last 2 years they bought 5 Proterra electric busses. Each cost more than twice what a normal diesel would, and currently all 5 are sitting in the garage. Most probably permanently out of service.

The company has gone bankrupt, and no replacement parts are available. Several need new batteries. They were supposed to last 6 years and have a range of 300 miles before needing to be recharged. In a period of less than 2 years they're down to a 100 mile range and are taking 8 to 12 hours to recharge. A couple need new parts for doors, but due to the current state of the manufacturer none are available.

Just to rub salt into the would the city has ordered another 60 electric busses from another manufacturer. This company has reported a $5,000,000.00 loss for the last fiscal year. How long will they last?

I got payback on my first set of panels in 4 years. PG&E changed the rules 2 years later, so I added a battery, an EV, and more panels for a 3 year payback. Of course PG&E changed the rules again…

 

[mksj]

You are probably running under NEM2.0 (NEM3.0 went into effect April 2023), you are credited for generated power for the time of day that it was generated. The power companies keep on changing their TOU rates, so they keep increasing the kW/hr rates after the sun goes down and lower the rates during mid-day when you are generating maximum power back to the grid. Most inverter systems track the power generated, so the first thing would be to look at if this changed as well as your consumption to see what difference is from prior years. I had a southern solar panel array (4.6kW) and 3 years ago put in a second western direction solar panel array (4.0kW), the latter can generate power until around 8 PM in the summer which adds generated power to the highest TOU which is 4-9PM. The second array has paid for itself in 3 years.

Solar option is based on where you live and power consumption during the year, power generation can offset costs during the summer months when consumption is typically higher in warmer climates. NEM3.0 is a deal killer for solar, as it pays you pennies per kW generated and charges you 10X or more when you consume it. Battery backup systems are stupidly expensive and with the current technology the batteries degrade over time and will probably need replacement every 10 years. So you are basically doing the job of the power company for power storage/generation as well as the cost. Maybe an option if you have money to burn, but appears to be quite impractical at this point in time to offset your TOU. My brother in northern California recently put in a 10kW solar array with batteries, in his case the solar array based on Enphase IQ8 micro-inverters and batteries were to cover for periods of no power (days) from PG&E outages. We are heading backwards in our power grids, adding more power consumption with EV's and all electric appliances, power rates keep climbing and more power outages are on the horizon.

As far as costs, the cost of goods has come down relative to solar panel output, but the cost of installation is still horrendous for the time involved in the install. The justification is that you get a tax credit which brings down the total system cost, providing you make enough to use it.

 

[ACHiPo]

You are probably running under NEM2.0 (NEM3.0 went into effect April 2023), you are credited for generated power for the time of day that it was generated. The power companies keep on changing their TOU rates, so they keep increasing the kW/hr rates after the sun goes down and lower the rates during mid-day when you are generating maximum power back to the grid. Most inverter systems track the power generated, so the first thing would be to look at if this changed as well as your consumption to see what difference is from prior years. I had a southern solar panel array (4.6kW) and 3 years ago put in a second western direction solar panel array (4.0kW), the latter can generate power until around 8 PM in the summer which adds generated power to the highest TOU which is 4-9PM. The second array has paid for itself in 3 years.

Solar option is based on where you live and power consumption during the year, power generation can offset costs during the summer months when consumption is typically higher in warmer climates. NEM3.0 is a deal killer for solar, as it pays you pennies per kW generated and charges you 10X or more when you consume it. Battery backup systems are stupidly expensive and with the current technology the batteries degrade over time and will probably need replacement every 10 years. So you are basically doing the job of the power company for power storage/generation as well as the cost. Maybe an option if you have money to burn, but appears to be quite impractical at this point in time to offset your TOU. My brother in northern California recently put in a 10kW solar array with batteries, in his case the solar array based on Enphase IQ8 micro-inverters and batteries were to cover for periods of no power (days) from PG&E outages. We are heading backwards in our power grids, adding more power consumption with EV's and all electric appliances, power rates keep climbing and more power outages are on the horizon.

As far as costs, the cost of goods has come down relative to solar panel output, but the cost of installation is still horrendous for the time involved in the install. The justification is that you get a tax credit which brings down the total system cost, providing you make enough to use it.

I think you’re right. I used to generate significant savings by generating solar energy to charge the battery, minimizing how much expensive electricity we used. The rates between peak and low aren’t much different now, so I’ve lost the savings from arbitrage.