Thinking about adding some solar power

[meburdick]

I live in a town where there's pretty much no public water supply (almost everyone has wells for their home use), no public sewer (we all have septic systems), and constrained access to "entertainment" service providers (phone, Internet, television). On top of that, we pay RIDICULOUS electrical rates.

I've been reading a couple of threads that deal with alternative energy choices, and have been starting to wonder how I could go about adding solar power to my home to offset the commercial power costs. My initial "target" would be to deal with a constant expense that I have in a radon mitigation system - there's a fan that runs 24/7.

Label on the side says 120V, 60Hz, 1.0A max. Also says 1/30HP Max. I was thinking that I could install solar PV panels, with a charger, batteries, and inverter, that I could use to power the fan motor for continuous duty. If I ensure enough reserve power to run the motor continuously for, say, three days, that would mean I would need to be able to store about 8.6KW of power in the batteries. In addition, I would need to be able to provide panels that could accumulate the 2.9KW of power that this thing uses every day AND add charge to the batteries at the same time. In order to have enough power to charge the battery, I would need panels that could supply 120W of power to run the motor and something like 180W of power to go toward charging the battery. This essentially means I would need three 100W panels which are about $575 for three. Given that this motor alone costs me something like $135 / year to operate, it will take me FOREVER (over four years, actually) just to recoup my costs on the panels alone.

Am I missing something here? If I'm doing the math right, then NO WONDER people aren't switching over to solar for even supplemental power!

 

[KTurner]

1.0Amp max does not mean 1.0Amp continuous. You should find a way to measure the actual current/power draw of the device and start from there. If the devices plugs into an electric outlet, there are devices (kill a watt) that you could put inline that will track several things for you. 1 HP is about 750 watts, so 1/30th HP is about 25 watts (ignoring the spike for startup). That would cut all of your numbers by a big percentage, since you could rely on the batteries for startup requiring less panels and battery storage. One thing you're not factoring in is that your fan is 120v AC and your solar panels/batteries are putting out ~12v DC.

My understanding is that solar water heating is much more efficient than using solar to power an electrical device. And, solar water heaters can be built from scratch using commonly available items (like pipes, lumber and paint), unlike PV panels and batteries.

Taking something fully off grid is going to be more expensive due to the batteries. Another thing you could consider is a micro grid tie inverter (GTI). It plugs into the grid and matches the grid signal, but puts power onto the grid. If the power goes out, it does you no good. but it's a lot cheaper to start off with. No batteries and it takes care of the 12v DC/120v AC. Throw a single panel and a GTI up somewhere. Tinker with it, use it to figure out how well solar does at your location, etc.

I've not done anything yet with solar except some research, but will probably start tinkering with either solar water heating or a micro GTI at some point soon.

Keith

 

[meburdick]

I don't seem to recall asking for logic and reason to be brought into the conversation.

Seriously... Your points about max power versus continuous are dead-on. I knew that the "max" meant that wasn't continuous, but I forgot that the disparity between startup and continuous on motors is so large.

Since this is a continuous-duty item, there *is* no startup to have to consider (really).

I'm aware of the difference in voltages, and planned on addressing that with an inverter. "Watts is watts", so I'm not concerned about the voltage or anything when factoring how much power to generate and store. While it's pretty likely that the motor will draw about 25-30W continuous, I'll still need to use the "extra" from a 100W panel to charge the battery packs. Since I'll need batteries, a charger, and an inverter, I think I'm still looking at a 2-3 year recover for my costs.

I'll have to look into the GTI item you mentioned... It sounds like it goes in line with the grid power so that I can operate "off grid" when power is sufficient for my needs, "on grid" when there's no sun, and in a sort of mixed mode when there's sun but my needs are higher than what the panel(s) can produce.

 

[Traxx]

you can also replace the motor with a straight dc motor and elimnate the inverter.

 

[meburdick]

True... I wonder what the cost of that would be compared to the cost of the inverter, though... And, wouldn't the use of the inverter, ultimately, give me cleaner power to run the motor on?

 

[KTurner]

Your points about max power versus continuous are dead-on. I knew that the "max" meant that wasn't continuous, but I forgot that the disparity between startup and continuous on motors is so large.

I suspect this also means that your yearly operating costs for the fan, as it sits now, is much less than the $135 you mentioned. $135 around here will get me about 1,200 KWH - getting close to what my power usage is for an average month (1,400 kwh). We're at about 11 cents per KWH.

Good news / bad news. It's cheaper to run the fan than you thought, but that means it'll take that much longer to break even on your solar investment.

Keith

 

[meburdick]

Very true.

So, again, it seems that I understand why so few people take on solar energy for their homes (unless you're talking about solar water heating, which is a little more prevalent).

 

[Traxx]

No the inverter is a unnessary expense. A solar panel powers a battery the battery powers the fan, the only inverter needed would be from 120 to 12vdc for cloudy days. The best return for investment is the solar water heater like mentioned above. Or just a timer for your water heater turn it on for just a couple hours a day would save a good bit.

 

[meburdick]

Current water heater is oil-fired burner on a hot water tank. The "issue" I have with it is that the house is a ranch and the main tank is "far" from the master bedroom.

We go through a lot of hot water in a day, so not sure how much benefit I would get from a solar system where I would need to maintain two tanks (I'm going to be putting in a second one under the master bath).

 

[Alien]

I installed solar (grid connected) but I don't see it as needing to break even in x number of years. I know I used to get a near $500 energy bill every 3 months and my last bill was a credit of $4.87. It is nice to know that what I am using I don't have to pay for anymore.
If you are going to be running gear at night-time you do need batteries and if there is no sun for extended periods you need to be grid connected.
This inverter is the ducks nuts for both situations. I guess there would be something similar in your part of the world. I just thought the info may help you with your decision. Selectronic - On-Grid Inverters with Battery Backup

 

[KTurner]

Very true.

So, again, it seems that I understand why so few people take on solar energy for their homes (unless you're talking about solar water heating, which is a little more prevalent).

I'd say so few people are doing it because the only tool in most people's toolbox is their checkbook.

It's all in the timing. You need to know what solar energy is available in your area (sticking up a 100W panel does not mean you always get 100W). If you want to store energy in your personal storage device (batteries) or use the grid as your storage (you get a 'credit' when your excess energy gets put on the grid during daylight, which 'cancels' the cost you pay for electricity that you need at midnight). Then look at the cost of solar equipment. And look at the cost of electricity in your area. It also makes a lot of sense to try to minimize your electrical requirements, so that you're not paying for a system that's really bigger than you need. Do you really need three TVs running all day? Then, when you've gathered all this information, consider that solar equipment costs are continually dropping and electrical rates are continually rising. You can estimate the rate at which your electric costs rise and factor that in your payback period formula. You could wait a couple years so the price of the equipment would drop some more. You could setup a formula to see how much the equipment needs to drop in price before you're satisfied with the length of the payback period - something like "I'm not going solar until it can pay for itself in eight years".

Less traditional aspects - I'm not a big fan of govt subsidies, but there are federal and local tax credit programs for installed solar systems. I think the federal program is 30% of the cost of the installed system. There are also companies that will foot the bill to install a solar system on your house, then charge you for the electricity it generates - SolarCity Solar PPA: Solar Power Purchase Agreement lets homeowners install solar power and save money every month with lower electricity costs.

Lots of things to consider.

Keith

 

[meburdick]

I installed solar (grid connected) but I don't see it as needing to break even in x number of years. I know I used to get a near $500 energy bill every 3 months and my last bill was a credit of $4.87. It is nice to know that what I am using I don't have to pay for anymore.
If you are going to be running gear at night-time you do need batteries and if there is no sun for extended periods you need to be grid connected.
This inverter is the ducks nuts for both situations. I guess there would be something similar in your part of the world. I just thought the info may help you with your decision. Selectronic - On-Grid Inverters with Battery Backup

That inverter looks interesting, but it also looks pricey.

I'd say so few people are doing it because the only tool in most people's toolbox is their checkbook.

It's all in the timing. You need to know what solar energy is available in your area (sticking up a 100W panel does not mean you always get 100W). If you want to store energy in your personal storage device (batteries) or use the grid as your storage (you get a 'credit' when your excess energy gets put on the grid during daylight, which 'cancels' the cost you pay for electricity that you need at midnight). Then look at the cost of solar equipment. And look at the cost of electricity in your area. It also makes a lot of sense to try to minimize your electrical requirements, so that you're not paying for a system that's really bigger than you need. Do you really need three TVs running all day? Then, when you've gathered all this information, consider that solar equipment costs are continually dropping and electrical rates are continually rising. You can estimate the rate at which your electric costs rise and factor that in your payback period formula. You could wait a couple years so the price of the equipment would drop some more. You could setup a formula to see how much the equipment needs to drop in price before you're satisfied with the length of the payback period - something like "I'm not going solar until it can pay for itself in eight years".

Less traditional aspects - I'm not a big fan of govt subsidies, but there are federal and local tax credit programs for installed solar systems. I think the federal program is 30% of the cost of the installed system. There are also companies that will foot the bill to install a solar system on your house, then charge you for the electricity it generates - SolarCity Solar PPA: Solar Power Purchase Agreement lets homeowners install solar power and save money every month with lower electricity costs.

Lots of things to consider.

Keith

Agreed all around. My "weapon" is money, and I'm a value-driven person. Yes, I understand that installing solar will reduce my electric bill. But, when does it come back to me and actually reduce my Total Cost Of Ownership? Everyone that buys a new refrigerator because theirs is 10 years old and much less energy efficient needs to have their head examined. Dropping $1,000 (most times, MUCH more) for an appliance that will save them $20/year in operating costs is plain foolish (I'm speaking ONLY of people that upgrade their appliances to get better energy efficiency). The amount of waste they put into landfills from that old appliance is ridiculous, so they aren't helping the environment either.

At the state level, there is NO rebate / refund / incentive for any system or part of a system over 10KW in size. What's there for federal, I don't know. I looked at the SolarCity site, but don't see information on what sort of actual electrical rate I might expect. It just says "at or below your current rate". Why would I want to have them put up all of that equipment to buy power at the same rate I currently pay? I understand that I would have a "fixed rate" at that time, but that only helps me if/when the rates go up.

 

[zonta223]

I installed solar (grid connected) but I don't see it as needing to break even in x number of years. I know I used to get a near $500 energy bill every 3 months and my last bill was a credit of $4.87. It is nice to know that what I am using I don't have to pay for anymore.

]

I am like the person above..My 3 monthly bill was $450..........current bill is about $30.
We are paying LOTS more for electricity than you do. Current rates here are about 30c a kw but any extra power we feed back into the power grid earns us 50+c A kw.
Thats why we love solar.

 

[meburdick]

I am like the person above..My 3 monthly bill was $450..........current bill is about $30.
We are paying LOTS more for electricity than you do. Current rates here are about 30c a kw but any extra power we feed back into the power grid earns us 50+c A kw.
Thats why we love solar.

My bill through the summer, which reflect usage of the pool pump and the central air conditioning on top of everything else, is typically in the $400 per month area. That, ultimately, drives my yearly usage and monthly average up quite a bit. Looking back over the past twelve months, I've spent just north of $3,000 on electricity charges. And, that takes into consideration the fact that we had a lengthy outage (running on generator) AND received a $100 credit from the power company because of the outage and it taking so long to restore. In reality, I should have incurred closer to $3200 in usage charges.

Based on *actual* charges, my average monthly bill is a little over $250. If I could get completely off of the grid, I'd save about $3,000 per year. I'm still thinking that I would be looking at a minimum of five years payback on the investment (assuming at least $15k out of pocket, but I'm betting it would ultimately be higher) unless I overbuilt and could sell power to the utility company and make the return happen more quickly.

 

[MtHam]

In today's economy an investment return of 5% is considered good. Savings accounts pay a measly 1-2%. If your electricity cost is $0.12/kwh (national average) or more, and you live in a part of the country where the sun shines a reasonable number of hours per year, the payback period on a grid tied solar electric system is about 10 years, or less. This means about a 10% return on your investment. As the cost of electricity goes up in the future (almost a certainty) the return increases. California has some of the highest electric rates in the country, and thus solar really makes sense, with the largest installed base in the country.

 

[NorTracNY]

I've done a grid tie system, but I did want a return in x number of years. It all depends on your state. Mine got an A rating for solar incentives and then allowed leasing which reduced the number of years on the return in half.

 

[meburdick]

If I had all of the cash in the bank earning interest, and knew for absolute certain that I would remain in this house for at least the next decade, then that could make a lot of sense for me.

Solar power is still "black magic" to a lot of folks, and trying to sell a house that is completely off grid will have a small percentage of folks that are willing to pay for it and a large percentage of folks that would shy away and be suspicious of it. So, I have to balance that in here too.

 

[meburdick]

I've done a grid tie system, but I did want a return in x number of years. It all depends on your state. Mine got an A rating for solar incentives and then allowed leasing which reduced the number of years on the return in half.

I'd be curious about the way you did your system (professional install, self install, combo), the size, whether you sell power back to the grid at any times or not, etc.... Also, I'd be interested to know how long ago you did it and at what sort of a "price range" you were at with the final costs.

 

[KTurner]

If I had all of the cash in the bank earning interest, and knew for absolute certain that I would remain in this house for at least the next decade, then that could make a lot of sense for me.

Solar power is still "black magic" to a lot of folks, and trying to sell a house that is completely off grid will have a small percentage of folks that are willing to pay for it and a large percentage of folks that would shy away and be suspicious of it. So, I have to balance that in here too.

Yea, I wouldn't do a solar install if I were planning to move. Like you say, most people would view that as a negative selling point, not a positive. You could still grab a GTI and one or more panels. no modifications needed to the house and you can easily unplug them and take them with you, or sell them, when you move. It'll get your feet wet with solar so that you'll have a better idea if you want to go full solar at your next house. And it may cut your power bill by a bit between now and then.

Keith

 

[meburdick]

I might consider making some calls to the local electric company, solar companies in the area, and even some of the home improvement companies. If I can at least talk to the folks that do the work and get an idea of what they offer and at what cost, I'll know if I want to do *something* with solar or not.

Good point on things that I can take with me. I wouldn't expect to be able to pack up and move a 50KW system (you never know, I guess), but certainly some smaller things might make sense. At the very least, I may consider a 100W panel with a charger and a couple of batteries to provide some lighting, operating a garage door opener, and maybe running the radio in my new shed. If I weld out there, or need more power, I will fire up the generator for when it's required. That will also ensure that the generator stays in good working order, too.