Newbie 101

goingtoghanagoingtoghana Solar Expert Posts: 34
Hello All,

So, I want to set up a small solar and wind system for an ophange in Ghana. They have tons of wind and the sun... well, it's really good.

We have limited resources, so I am thinking we want to do a non-battery system and tie directly into the grid.

My question is... what is the safe, LEGAL (think U.S. for now) way to do this? I read about the grid-tie inverters that plug into the wall and how they are not safe or legal. How do you actually make the connection? Are there UL approved inverters that you wire into the box?

Thanks,

Chuck

Comments

  • solar_davesolar_dave Solar Expert Posts: 2,367 ✭✭✭✭
    Re: Newbie 101

    Yes Chuck there are grid tie inverters. You need to understand they only work while the grid is up, and require a fairly stable grid to operate for both frequency and voltage.

    The panels are setup in strings to get the DC voltage up, and run into an combiner for their trip to the inverter, the inverter has an AC out that gets put into the main breaker panel as a back feed. In the US that can only be 20% of the bus bar rating on the main panel unless you derate the main breaker..
  • BB.BB. Super Moderators, Administrators Posts: 31,038 admin
    Re: Newbie 101

    Why do you want to set up Grid Tied Solar? To save/make money?

    Does the local utility even allow Grid Tied systems and support the billing with a Net Metering plan? This is not common outside of North America, Europe and possibly some Asian countries...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    BB. wrote: »
    Why do you want to set up Grid Tied Solar? To save/make money?

    Does the local utility even allow Grid Tied systems and support the billing with a Net Metering plan? This is not common outside of North America, Europe and possibly some Asian countries...

    -Bill

    The whys are definitely to save money for the orphanage we support. The funds will be donated so the payback isn't really and issue. We are thinking of using both because they have unreal sun and the wind blows constantly as they are within a 10 miles of the ocean.

    I have not approached the local utilities yet. I'm trying to obtain as much knowledge as I can before I speak to them. We are not looking to replace all, but just supplement what they use. If they make more then they use, I guess the electric company could benefit at our cost. I have seen their meters and they are manual. They look like an old-fashioned car odometer.
  • BB.BB. Super Moderators, Administrators Posts: 31,038 admin
    Re: Newbie 101

    More than likely, the local utility will only support net metering/grid ties solar if the government makes it.

    By the time you purchase (and ship?) the equipment down there, more than likely the power you generate will cost more than buying the power from the utility (assuming they already have grid power).

    This is probably doubly true if you were to install any of the smaller Wind Turbine GT systems.

    Also, if you do not have anyone on-site (and spares) to keep the system operating, it will probably fall into eventual disuse.

    In any case--We normally suggest a comprehensive study of their energy usage first. Then spend the time and money on conservation (insulation, sealing the building against wind and humidity--if applicable, replacing older electrical equipment with new EnergyStar type low power; replacing desktop computer with laptops/new efficient systems, timers, turning off stuff not in use, energy efficient CFL/LED lighting, etc.). This is almost always offers a better return on investment than Solar RE.

    Once that has been done--then it may make sense to look at Solar Thermal (hot water, even space heating) and Solar Electric of some sort. And lastly wind power.

    -Bill "In my humble opinion" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Newbie 101
    The whys are definitely to save money for the orphanage we support. The funds will be donated so the payback isn't really and issue. We are thinking of using both because they have unreal sun and the wind blows constantly as they are within a 10 miles of the ocean.

    I have not approached the local utilities yet. I'm trying to obtain as much knowledge as I can before I speak to them. We are not looking to replace all, but just supplement what they use. If they make more then they use, I guess the electric company could benefit at our cost. I have seen their meters and they are manual. They look like an old-fashioned car odometer.
    I'd look at the wind option very carefully before spending any money on it. With solar we can estimate pretty well what a system in a particular location will produce based on climatological and astronomical databases, and most of the solar gear sold works in about the same way and produces about the same amount of energy.

    Wind is a different story. To do a wind installation, you should really set up a weather station at the precise location and height where you want to set up a turbine and take data for a year to make sure the resource is really there. Then you'll want to research the different equipment options very diligently to weed out the huge array of junk being sold that either does not work at all or underperforms badly. Just throwing up any old turbine where the wind blows your hair around is nearly always a doomed endeavor. You may very well be better off spending that money on more solar.

    No offense intended, but from what you say it appears that you do not yet have a great deal of experience in renewable energy. Be advised that there is a lot of charlatanism in the small wind business and there are sharks out there looking for folks like you to take advantage of. Caveat emptor.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie 101

    First thing to do is find out what the local utility rate is, including the 'base costs' and other add-ons so you have some idea how much the electric is per kWh over-all. Then find out if you can sell back to the grid and at what rate.

    Without the ability to sell back to the grid you would be be putting in what is essentially an off-grid system, even though it may be battery-less and merely negate grid consumption. We have a pretty good idea how much that costs per kWh, and it it isn't cheap.

    Just trying to look out for you so you don't fall into the trap of false economy that is prevalent in solar power. Possibly the money could be better spent, especially at an orphanage.
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    ggunn wrote: »
    Just throwing up any old turbine where the wind blows your hair around is nearly always a doomed endeavor. You may very well be better off spending that money on more solar.

    No offense intended, but from what you say it appears that you do not yet have a great deal of experience in renewable energy. Be advised that there is a lot of charlatanism in the small wind business and there are sharks out there looking for folks like you to take advantage of. Caveat emptor.

    this is very interesting, and yes, I am a complete newbie. I have learned alot quickly, but many more answers then questions.

    As far as the wind goes, it is in-between two mountain ranges and the wind just funnels through from the ocean constantly. I get what you are saying about studies, but I was thinking about putting up a small one to start. Say one of many that are in the 700 to 1000 W range. Are you saying that most of these are poor quality?

    It just seems a shame to waste such great sun and wind. I can't imagine a more perfect place where the application fits.
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    BB. wrote: »
    By the time you purchase (and ship?) the equipment down there, more than likely the power you generate will cost more than buying the power from the utility (assuming they already have grid power). B.

    One of the things we have looked at the lower cost is the flexible panels that fit on a metal roof. It is what they have and given the weight, I can bring 6 over per person in checked luggage. We go over there alot anyway, so I could slowly add panels each trip. I agree, shipping them would make it not worthwhile.

    Are the flexible panels worthwhile? $289 for 124Watts each with no real installation cost for the panels seems pretty cheap. ( This is so obviously a newbie statement)
  • BB.BB. Super Moderators, Administrators Posts: 31,038 admin
    Re: Newbie 101

    I am not a fan of flexible panels... I am not sure they will last more than 1-10 years in the sun (depending on lots of details). Also, they need almost 2x the roof space because (usually) they are not as efficient as normal glass covered crystalline solar panels. If you get them cheap and they meet your needs, then they can be a good solution for some installations.

    I am also not a fan of small wind (and big wind is iffy too). Here are some links to read (however, there are people with wind turbines that are happy--normally they luck into a decent vendor and do a lot of the maintenance themselves):

    Wind Power Links
    www.otherpower.com (good forum for DIY Wind Power)
    Hugh Piggott - Scoraig Wind Electric site for tons of info (from mike90045)
    www.greenpowertalk.org (added from "russ"--Like here but more wind/less solar)
    Small windpower a scam ? Survey says SO
    Truth About Skystream & SWWP
    Windmax HY-2000 2kW Wind Turbine (apparently, some vendors don't sell spare parts--just new turbines)

    And a general DIY Solar Builder site:

    www.builditsolar.com

    -Bill "The Grinch" B. :roll:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Newbie 101
    this is very interesting, and yes, I am a complete newbie. I have learned alot quickly, but many more answers then questions.

    As far as the wind goes, it is in-between two mountain ranges and the wind just funnels through from the ocean constantly. I get what you are saying about studies, but I was thinking about putting up a small one to start. Say one of many that are in the 700 to 1000 W range. Are you saying that most of these are poor quality?

    I'm saying do your homework before you spend a dime on gear, and with wind there is a LOT more homework to do than with solar.

    As to the wind resource, it is virtually impossible to judge if the wind resource in a particular area is worth harvesting by simple observation. What makes for a good decision is long term observation and data crunching. Sure, you might luck out but the odds are against you.

    Most of the serious studies of small wind generators I have seen have shown poor to downright dismal results. Do NOT trust "statistics" published by the manufacturers on their own equipment, but get independent verification of quantifiable results. I'll tell you up front that such data is not easy to find for wind. For solar it's a snap.

    I'm guessing that these folks don't have deep pockets. If it's their money you are spending, then you owe it to them to hedge your bets as much as you can, and small wind is very risky.
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    solar_dave wrote: »
    Yes Chuck there are grid tie inverters. You need to understand they only work while the grid is up, and require a fairly stable grid to operate for both frequency and voltage.

    The panels are setup in strings to get the DC voltage up, and run into an combiner for their trip to the inverter, the inverter has an AC out that gets put into the main breaker panel as a back feed. In the US that can only be 20% of the bus bar rating on the main panel unless you derate the main breaker..

    Are the grid tie inverters you talk about just like the ones that plug into the wall with the exception that they are wired into main breaker panel?
  • BB.BB. Super Moderators, Administrators Posts: 31,038 admin
    Re: Newbie 101

    Yes.

    The normal grid tied inverters are available in ~230 VAC 50 or 60 Hz, and some (typically smaller units) are available in 120 VAC (50/60 Hz?). These are hardwired into the main AC building panel.

    The issue with Plug-in GT inverters is that there is no way for a regulatory agency or building inspector to ensure that somebody does not plug too many GT inverters into one branch circuit... It is possible that somebody could overload the branch circuit with too much current--Or a short circuit elsewhere (office lamp as an example) will now get current from both the AC panel + circuit breaker plus more current from the GT plug-in inverter (shared power sources on one branch circuit).

    Because it is (as far as I can tell--my personal opinion) impossible to get "UL" (NRTL) Listing on a plug-in GT AC Inverter, then there is no way of ensuring that those inverters otherwise are designed to meet, and manufactured under NRTL review.

    Are plug-in inverters "dangerous" if built well and used correctly. No, probably not.

    Are plug-in inverters well designed (regarding safety and fire hazards) and built under NRTL requirements. Have know way of knowing, but probably not since no agency could List the inverters as they would not meet code with a plug on the end (again, as I read the requirements).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    BB. wrote: »
    Yes.

    The normal grid tied inverters are available in ~230 VAC 50 or 60 Hz, and some (typically smaller units) are available in 120 VAC (50/60 Hz?). These are hardwired into the main AC building panel.

    The issue with Plug-in GT inverters is that there is no way for a regulatory agency or building inspector to ensure that somebody does not plug too many GT inverters into one branch circuit... It is possible that somebody could overload the branch circuit with too much current--Or a short circuit elsewhere (office lamp as an example) will now get current from both the AC panel + circuit breaker plus more current from the GT plug-in inverter (shared power sources on one branch circuit).

    Because it is (as far as I can tell--my personal opinion) impossible to get "UL" (NRTL) Listing on a plug-in GT AC Inverter, then there is no way of ensuring that those inverters otherwise are designed to meet, and manufactured under NRTL review.

    Are plug-in inverters "dangerous" if built well and used correctly. No, probably not.

    Are plug-in inverters well designed (regarding safety and fire hazards) and built under NRTL requirements. Have know way of knowing, but probably not since no agency could List the inverters as they would not meet code with a plug on the end (again, as I read the requirements).

    -Bill

    Perfect. Thanks so much
  • SevenSeven Solar Expert Posts: 292 ✭✭
    Re: Newbie 101

    What do you pay for electricity there?
    As others have said, conserving through better insulation, efficient appliances, LED lights, etc, is much more cost effective than solar.
    If you install a $10K system and it only saves you $.55 a day your money would have been better spent on new windows and added attic insulation.
    You say you are not worried about payback because of donations, but it seems to me that you would want the most for the dollars that people are donating. I know I would if I was the one donating.
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    Seven wrote: »
    What do you pay for electricity there?
    As others have said, conserving through better insulation, efficient appliances, LED lights, etc, is much more cost effective than solar.
    If you install a $10K system and it only saves you $.55 a day your money would have been better spent on new windows and added attic insulation.
    You say you are not worried about payback because of donations, but it seems to me that you would want the most for the dollars that people are donating. I know I would if I was the one donating.

    Lots to address here. First, the building is in Ghana. They use CF bulbs for light, open windows and ceiling fans for cooling and the obviously don't need heat. They have one TV, 1 stove and 1 frig and 2 freezers. There are other odd and end usage (laptop, radio etc..)

    They do use on avg 900 KWh a month at a cost of .115 USD/KWh for a bill of around 103 USD/mth

    The equipment I think I need (I'm still researching)

    8 - 124W Flexible Panels @ $289/ea
    1 - Combiner
    1 - Grid tie Inverter
    1- A/C shutoff
    Wire
    breakers
    meters

    I'm thinking this would be in the $3000 - $3500 range.

    Since they get 8 - 10 hours of equatorial sun each day, I'm thinking I can provide about 1/3 of their monthly usage with a payback period of some where around 7 to 8 years.

    Is it worth it? Is that a good payback period on donations?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie 101

    The numbers don't look good. For one thing, $0.11 per kW hour is pretty cheap electric. GT produced power is roughly 5 times that.

    For another, your panel choice:
    8 * $289 = $2,312
    8 * 124 Watts = 992 Watt array

    I don't know of any GT inverters that could make use of that size array. SMA has some small ones at 700 Watts, but usually GT is 3kW or more. Enphase or other microinverters might be a better choice, but they need to be used with recommended panels and these 124 Watt ones may not meet that requirement.

    The SMA 700 Watt inverter is $1,100 at our host http://www.solar-electric.com/smasugrtiein.html and that would put your total up to $3,412 before all the install hardware.

    As a rule GT systems become more economical the larger they are, especially if you can sell surplus power.

    Perhaps someone else has a better idea of equipment that could be used to meet your goals.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Newbie 101

    in addition to what cariboocoot said you would not need a combiner as the pvs would be in series to gain the necessary voltages for gt. it would be better to get the higher wattage pvs anyway as they are cheaper per watt.

    odds are the people there would not be all that impressed and may start to think they don't need as much conservation as they may think the solar is providing it. misnomer of solar as it is not unlimited power.

    they may come to appreciate it if power outages occur often there, but then battery backed gt is not as efficient and has a longer payback period. when the power is out, having backup can seem priceless. if this is automatic they wouldn't even know the power went off, but let the lights go out and you flip the switch and they change their tune. human nature is strange at times in that you have to take away their complacency without blame to yourself for them to see the true benefit.:roll:
  • goingtoghanagoingtoghana Solar Expert Posts: 34
    Re: Newbie 101
    niel wrote: »
    in addition to what cariboocoot said you would not need a combiner as the pvs would be in series to gain the necessary voltages for gt. it would be better to get the higher wattage pvs anyway as they are cheaper per watt.

    odds are the people there would not be all that impressed and may start to think they don't need as much conservation as they may think the solar is providing it. misnomer of solar as it is not unlimited power.

    they may come to appreciate it if power outages occur often there, but then battery backed gt is not as efficient and has a longer payback period. when the power is out, having backup can seem priceless. if this is automatic they wouldn't even know the power went off, but let the lights go out and you flip the switch and they change their tune. human nature is strange at times in that you have to take away their complacency without blame to yourself for them to see the true benefit.:roll:


    I'm actually to the point of punting the whole thing and giving them a back-up propane generator for their frequent blackouts. Batteries seem like such an expensive waste over time. I'll admit I'm bummed. It doesn't seem like solar makes much sense any any application unless it is for moral purposes.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Newbie 101

    a generator would be the same as you having the solar back up system with batteries and a flip of a switch on both would show what they are producing and would appreciate it in that seeing. no moral issues here, just dumb human nature is all. a generator is cheaper if you can deal with the getting of the gasoline which is an added cost for those kilowatt hours.

    you could talk it over with everybody and let them decide how to do it. in your citing a generator this means it is for outages. could you elaborate on the frequency of the outages and generally for how long? feedback from us on it and shared with them could bring an understanding of what is involved and what they would decide upon getting. you are blameless in this way.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Newbie 101
    I'm actually to the point of punting the whole thing and giving them a back-up propane generator for their frequent blackouts. Batteries seem like such an expensive waste over time. I'll admit I'm bummed. It doesn't seem like solar makes much sense any any application unless it is for moral purposes.
    IMO, you should separate the two issues of reducing the overall electric bill and covering grid outages.

    Grid tied PV can be very good for the first issue if the system is well designed, if the customer can take the economic long view, and if the relatively low hanging fruit of energy conservation is addressed first.

    For the second issue the solution can either be a generator or battery backup (or nothing - just hunker down and wait for the grid to come back up). The economics/logistics need very close scrutiny, as any sort of backup is going to be expensive. For infrequent short interruptions of power, a generator is nearly always going to be the more economical choice.

    Good luck with your project, and kudos for helping folks who need it.
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