Is now a good time to invest in solar?

[OmCheeto]

Yes, but only diffuse light. Nothing normal to the plane of the panel. So the question is what is the impact of diffuse light. I dunno. Per Artman's results there likely is some impact.

I am quite certain that I am reverting back to my nerd-like childhood.
Yesterday I did experiments on my solar panels whilst I could have been sitting at the beach.

a. Solar panel output is, not surprisingly, directly proportional to the face area of direct sunlight.
b. Nerdish fact that I'd forgotten: One must place a plane 60' out of perpendicular with the sun before area drops to 1/2.
c. at an angle of 40', Artman's panels would be absorbing 64.3% of the full energy reflected by the snow. (assuming an infinite backyard )
d. the albedo of my lawn is ~11.4%(8.76% output, fully shaded, @ ~56.3' angle from horizontal)

 

[mheslep]

c. at an angle of 40', Artman's panels would be absorbing 64.3% of the full energy reflected by the snow.

There you are then; I suppose that explains the power boost w/ snow on the ground. That, and the cold temperatures which improve efficiency.

 

[morris99]

It is definitely a good time to take a solar heater.Since they already announced that you need to use the things like green energy sources this would be the best time...




water systems.html]Solar hot water[/url]

 

[Artman]

We just signed up to increase insulation in our attic, replace our AC unit with a High performance HP that can heat effectively down to 30 below 0, and install a Heat Pump Domestic Water Heater with resistance backup. The insulation, higher efficiency HP equipment, and switch to Heat pump water heater should allow for zero impact on our electrical usage and allow us to eliminate most fossil fuel use in our our house (Oil fired boiler would remain as a backup, but probably won't ever run.) Basically, we are soon to be all solar powered.

This all happened as a result of the required energy audit that was performed as part of the solar installation process. There is an Energy Star NJ rebate program that will pay $3000 towards the changes and another NJ State program that will give a $10,000 no interest loan for 10 years.

Conservative payback estimates are for 20 years, I would guess closer to 10 years just from our oil savings potential and more efficient AC. The Acadia Air-to-Air Heat Pump is supposed to be almost as efficient as geothermal, without the cost for wells.

http://www.gotohallowell.com/Acadia™-Products/the-acadia-30.html"

 

[marcos248272]

I have work in the big company and I'd like to propose to use this solar energy. Can you help how to make a proposal. Do you have a study that this is now a good time to switch into solar ? Please help.

 

[russ_watters]

I have work in the big company and I'd like to propose to use this solar energy. Can you help how to make a proposal. Do you have a study that this is now a good time to switch into solar ? Please help.

There is no blanket answer to that question. Every case must be considered on an individual basis.

 

[shilpaam1]

Today the demand is so strong for electricity.We have to find other ways how to produce it.Solar Energy is the solution to this problem :)


http://www.googlesniperrevealed.com//

 

[mheslep]

http://www.googlesniperrevealed.com//

Advertising/Spam:
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https://www.physicsforums.com/showthread.php?t=414380

 

[Artman]

I have work in the big company and I'd like to propose to use this solar energy. Can you help how to make a proposal. Do you have a study that this is now a good time to switch into solar ? Please help.

My experience is with residential solar, but I agree with Russ:

There is no blanket answer to that question. Every case must be considered on an individual basis.

I can tell you this though, incentives in the USA are probably the best they will be, compared to the future, right now. They are already dropping and not as high as when I installed my system, less than a year ago. My state is considering doing away with their rebate program because of the incentive value of the SREC program. Also, the SREC prices are going to drop as more and more people install solar arrays (the predicted price for an 2011 SREC in NJ is $600, currently, 2010 SREC's in NJ are selling for $664).

You more than likely won't "Switch to Solar." Solar is an intermittent energy source, it needs to be added as a redundant system to conventional energy sources, such as a power grid for photovoltaic or fossil fuel for solar thermal or have some form of energy storage (batteries, heated water tanks, etc). Also, arrays designed to offset 100% of industrial loads could be very large and very costly (my 8.8 kW array is 12'x56' and made of 40 panels and cost approximately $74,000). "Supplement with Solar" would be a better way of phrasing what you would more likely be proposing.

 

[Artman]

Today the demand is so strong for electricity.We have to find other ways how to produce it.Solar Energy is the solution to this problem :)

Solar helps offset the demand for electricity during daylight hours only. Say a house with a solar array produces 3x what it uses, you might think that the power grid could be reduced in capacity by that amount, but what about cloudy days? Or nighttime? What it does do is to reduce the amount of energy used to create the electricity that powers the grid during the hours they are producing. Solar helps, but it is not currently the solution.

 

[donbcg]

The difference lies in cost benefit ratios.

A solar panel is by far the least economical in terms of power production. They can only generate at a 12% - 18% efficiency. The rest is lost to heat. Secondly, the amount of panels to create such a system would be in the nature of 1200 sqft. Lastly, they break. Not frequenly, but when they do it's very expensive to repair. And most systems are built with series circuits. If one goes down, they all go down.

I suggest that you do it understanding one thing, they are toys at best for now. It takes over 10 years for ROI, and by then you money and investment may be obsolete. The technology is such that it could very well be similar to computers. Some parts are interchangable, but the parts you need most are not.

Just my opinion. Alternative energy is what it says, alternative. Not replacement.

 

[mheslep]

The difference lies in cost benefit ratios.

A solar panel is by far the least economical in terms of power production.

By far? ~20 cents / kWh in sunny climates, large scale.

They can only generate at a 12% - 18% efficiency.

17-22%

The rest is lost to heat.

Some is lost to heat in the panel, some is reflected.

Lastly, they break. Not frequenly, but when they do it's very expensive to repair. And most systems are built with series circuits. If one goes down, they all go down.

They're built with both: parallel chains of panels in series. And everything breaks.

I suggest that you do it understanding one thing, they are toys at best for now. It takes over 10 years for ROI, and by then you money and investment may be obsolete. The technology is such that it could very well be similar to computers. Some parts are interchangable, but the parts you need most are not.

Flawed comparison. For products with low or zero cost to operate that generate a commodity (energy in this case) obsolescence doesn't matter much - the PVs still produce energy and cash flow.

Just my opinion. Alternative energy is what it says, alternative. Not replacement.

Not yet. Five years, ten at the outside my guess PV probably becomes cost effective with coal up and until PV would cut into baseload needs, and that's a way to go yet.
http://www.1366tech.com/v2/company-mainmenu-1/reaching-coal-parity

 

[Artman]

Not yet. Five years, ten at the outside my guess PV probably becomes cost effective with coal up and until PV would cut into baseload needs, and that's a way to go yet.

Still, it will be alternative energy until storage becomes feasible.

I suggest that you do it understanding one thing, they are toys at best for now.

Solar yard lights are toys. My solar array is an 8.8 kW generator that can produce enough kWh in 6.5 hrs of decent sun to power my house all day. Agreed solar is not for everyone, requires a lot of space for serious capacity, and the technology is still in its infancy, but I know people who have been using it for years and are very happy with the results and so far, so am I.

It takes over 10 years for ROI, and by then you money and investment may be obsolete. The technology is such that it could very well be similar to computers. Some parts are interchangable, but the parts you need most are not.

There is zero ROI on using the grid for all of your electrical power. It's like renting a house instead of buying one. In ten years, my electricity will be free. True, the current technology will probably be obsolete, but the panel warranty is for twenty-five years and the panels are said to last for 40 years. That's long enough for me.

In fact because of incentives, my electricity is free now. The SREC sales are beginning to pay off my loan and my meter is 600 kWh to the negative.

 

[mheslep]

Still, it will be alternative energy until storage becomes feasible.

Well that depends on what you mean by alternative. Is wind alternative now, with a US capacity ~40 GW by the end of this year (highest in the world)? If you mean solar can't replace base load, 24/7 power without storage, I agree, but I suspect solar or wind can make up 20-30% of all US electrical power before the intermittent limitations of non-backed up solar/wind become intractable problems.

 

[mheslep]

Artman -

Regarding breakage from hail/tree limb/kids baseball, do you have some idea of how to handle replacing the panel? I would think with all the structure and wiring in place that you could easily replace one panel yourself by accessing half a dozen fasteners.

 

[russ_watters]

Well that depends on what you mean by alternative. Is wind alternative now, with a US capacity ~40 GW by the end of this year (highest in the world)? If you mean solar can't replace base load, 24/7 power without storage, I agree, but I suspect solar or wind can make up 20-30% of all US electrical power before the intermittent limitations of non-backed up solar/wind become intractable problems.

Plus, since solar's peak output corresponds well with the peak grid load, the types of power plants used for for meeting the peak demand are the ones being displaced: and those are almost exclusively fossil fuel plants. So it dovetails nicely with the type of energy we most need to displace.

 

[mheslep]

Artman - heads up:
http://www.technologyreview.com/energy/25963/

The power output of solar panels can be boosted by 10 percent just by applying a big transparent sticker to the front. Developed by a small startup called Genie Lens Technologies, the sticker is a polymer film embossed with microstructures that bend incoming sunlight. The result: the active materials in the panels absorb more light, and convert more of it into electricity.
[...]
Tests at the National Renewable Energy Laboratory showed that the film increases power output on average between 4 percent and 12.5 percent, with the best improvement under cloudy conditions, when incoming light is diffuse. Adding the film--either in the factory, which is optimal, or on solar panels already in use--increases the overall cost of solar panels by between 1 percent and 10 percent...

 

[blimkie.k]

Artman, are you planning on testing out the transparent sticker?

If you do let me know how it works for you. My boss and I are planning on putting a 10 kw system on one of the companies properties. Were just waiting for the ontario micro fit application to pass. However they are saying the kwh rate might be lowered from 88 cents to 55 cents so we may not go ahead with it.

I would also have to check whether or not the panels we would be getting allready have the transparent sheet attached or not.

 

[mheslep]

Were just waiting for the ontario micro fit application to pass. However they are saying the kwh rate might be lowered from 88 cents to 55 cents so we may not go ahead with it.
.

Aside - electricity costs 88 cents per kilowatt hour in you area? Where may I ask? More to the point, why?

 

[blimkie.k]

Aside - electricity costs 88 cents per kilowatt hour in you area? Where may I ask? More to the point, why?

Sorry, electricity only costs labout 8 or 9 cents a kw/h from Ontario Hydro. The rate they pay per kw/h with a 10 kw system or less is 80.2 for rooftop and 64.2 for ground mounted. It used to be 88 and they were going to change it to 55 so they must have settled on those numbers.

http://microfit.powerauthority.on.ca/microFIT-Program-Rules/microFIT-Program-pricing/index.php

They lowered the ground mounted rate because its cheaper to do a ground mounted system because of extra engineering costs and possible roof reinforcement.

I believe they want to be able to say so many percent of Ontario's power comes from renewable energy so by paying people higher rates its compensating them for installing solar 10 systems for the government. If you build a system for microfit you are not harvesting power from it for your home it all goes to the grid. Unless you want to build a 20 kw system and have 10 for you and 10 for the grid.

 

[Artman]

Plus, since solar's peak output corresponds well with the peak grid load, the types of power plants used for for meeting the peak demand are the ones being displaced: and those are almost exclusively fossil fuel plants. So it dovetails nicely with the type of energy we most need to displace.

This is very true. I did an HVAC project for a coal fired generating station that was used specifically for peak demand loads only.

blimkie.k and mheslep, more than likely, I won't be using the new sticker technology unless they pass legislation allowing me to sell back the excess energy at retail rates. There is some question as to longevity effects of the product (collection of dirt, scratching, discoloration, etc). However, I may consider it if switching to a heat-pump for heat makes my usage rise significantly, but it shouldn't, we hope, since we are also switching to a heat-pump water heater from a resistance electric type, increasing insulation, and the cooling efficiency is higher in the new heat-pump than in my old AC unit. Right now my solar array meets my house usage and a little over.

 

[mheslep]

blimkie.k and mheslep, more than likely, I won't be using the new sticker technology unless they pass legislation allowing me to sell back the excess energy at retail rates. There is some question as to longevity effects of the product (collection of dirt, scratching, discoloration, etc).

Yes, though there may be another side to the deterioration of the the sticky film, in that in protects the underlying surface panel. As an uncoated panel surface degrades from the elements you are stuck with it. With the film, maybe you replace it every ~7 years and return to a higher power output, cost basis permitting.

 

[Artman]

Yes, though there may be another side to the deterioration of the the sticky film, in that in protects the underlying surface panel. As an uncoated panel surface degrades from the elements you are stuck with it. With the film, maybe you replace it every ~7 years and return to a higher power output, cost basis permitting.

Yeah, I thought that too. As a further layer of protection they may have some value, however, my panels are pretty tough. They are supposed to be able to withstand a 1" diameter projectile (like hail) at 40 mph. My main point is that I don't currently need it to meet my load, so the the extra cost isn't warranted. Should switching to a heat-pump push us over our electric production, it might be worth the investment.

 

[mheslep]

Yeah, I thought that too. As a further layer of protection they may have some value, however, my panels are pretty tough. They are supposed to be able to withstand a 1" diameter projectile (like hail) at 40 mph.

I'm not referring to breakage. We know that panel output degrades at something like 0.5-2% per year. Part of that may be due to a degradation of the panel surface from simple abrasion over time, I don't know, and maybe a simple polishing would remove that effect. But if not, in 15 years, if your system is down 30% from today (extreme worst case), will that still be sufficient?

 

[Artman]

I'm not referring to breakage. We know that panel output degrades at something like 0.5-2% per year. Part of that may be due to a degradation of the panel surface from simple abrasion over time, I don't know, and maybe a simple polishing would remove that effect. But if not, in 15 years, if your system is down 30% from today (extreme worst case), will that still be sufficient?

I hadn't thought about that as a possibility. I'll ask my installer what he thinks about the film.

 

[OmCheeto]

I hadn't thought about that as a possibility. I'll ask my installer what he thinks about the film.

I'd also contact the manufacturer to see if it would void your warranty. It strikes me that a film on glass would restrict heat flow. And you know how hot they get already.

And I doubt the reduction in panel efficiency over time has anything to do with the glass.

 

[mheslep]

I'd also contact the manufacturer to see if it would void your warranty. It strikes me that a film on glass would restrict heat flow. And you know how hot they get already.

Yes, if the film increases the infrared trap then maybe so. I doubt conductive heat flow is changed on the surface.

And I doubt the reduction in panel efficiency over time has anything to do with the glass.

Well we know this much:

A dust layer of 4 grams per square meter can decrease solar power conversion by 40 percent, [...] To put this in perspective, dust deposition in Arizona is about 17 grams per square meter per month[...]

I don't know how much transmission might be typically lost in the surface glass (or polymer?) over time, but obviously surface impairment matters.

http://www.scientificamerican.com/blog/post.cfm?id=self-cleaning-solar-panels-could-fi-2010-08-22

 

[mugaliens]

Its interesting reading through this, as I designed a simple 4'x8' solar water heating system for my parent's place to be connected to a radiator in the basement. It's just supplemental, tied into the central air thermostat for activation. I tilted it to our latitude less 23 degrees for maximum influx during the winter.

Total cost is less than $400, not including labor. I estimate it'll take me about 20 hours for the install, but Dad's a little hesitant. I calculate it'll save him $400 a year, and the system should last 5 to 10 years with little or no maintenance.

One question I have is whether or not it needs a pump. Obviously, an appropriately-sized pump would increase its efficiency and heat output signficantly. My question is whether there's enough thermal expansion of heated water alone to power at least basic movement of the water. It sports about 100' of black hose in the collector, which is turned sideways, so only 4' tall. Entry is at the bottom and exit at the top, the reverse of the radiator. Line runs between the collector and the radiator are approximately 50', total, with standard 1/2" PVC piping. It's insulated only on the outside, as the purpose once inside is to heat, so if it heats, it heats.

Back to the question? Do I need a pump?

 

[Mech_Engineer]

One question I have is whether or not it needs a pump. Obviously, an appropriately-sized pump would increase its efficiency and heat output signficantly. My question is whether there's enough thermal expansion of heated water alone to power at least basic movement of the water.

The only method of natural flow of the water would be through natural convection, and for that to work the heat source has to be below the radiator. Convection flow also wouldn't work very well in a piped system. Just get a small pump, they aren't THAT expensive...

 

[Artman]

If it's a closed loop you may need a few things. It should have a small expansion tank for expansion compensation, over-pressure/temperature relief valve, and freeze protection (propylene glycol or some other antifreeze), depending on possible temperatures at nights and cloudy days. These may not be required with a plastic pipe loop like you described, but you should consider them.

It may work without a pump by placing the return connection at the top of the panel and the inlet supply at the bottom, but in a closed loop I'm not sure it will help. You could try that first.

Since you describe this as supplemental, you could put in a solar powered DC pump to circulate the system only when the sun is out heating the water. That will add to the cost of the system, however it might make back enough in electric savings over non solar pump over time to pay it back, should you find a pump is necessary.