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Where to start - converting from generator/UPS to more reasonable solar / powerwall?

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  • Where to start - converting from generator/UPS to more reasonable solar / powerwall?

    Looking for advice on where to start; my situation is a bit more complex than the scenarios I've read about so far due to my existing system, so thought I'd start with this post.

    Will caveat up front that I'm not a "green for the sake of green" person, I was trained as an electrical engineer so I like the tech, and I get the long term benefits of going green, but I'm a pragmatic finance oriented guy so I need things to also make financial sense before I proceed.

    My situation:
    I recently relocated to upstate New York and bought my 15 year old house for a song (about 30% of construction cost) because the house was built at the peak of the last economic cycle and the city and local businesses have been in decline or slow growth mode since. Homes don't really appreciate in this market regardless of what you do to them so any investment you make is typically gone. The guy that built my house was very wealthy and was a techie, so my house is large and was built with high end commercial-only (at the time) tech. Much of that tech has become obsolete or has trickled down into residential applications now. I've been opportunistically replacing systems as they fail with new and inexpensive tech (swapped out whole-house stereo / CD / DVD / Direct TV entertainment with roku / sonus, swapped plasma TVs with LCDs, swapped out networked thermostats with Nests, etc) to lower operating costs, save energy, and achieve (someday) an iphone controlled / connected home.

    Opportunistic is important because life has "happened" repeatedly such that the longest I've lived in a given domicile over the past 20 years is 3 years (I've been bounced from my homes for work / marriage / kids). I'm hoping for something much longer this time around (which is why I relocated), but hard to read the tea leaves. Therefore even though I have a strong interest in investing in my house, I'd like whatever I do to have an ROI of 1 year or less or "zero cash investment + net lower monthly cost" so I don't get burned when life happens again.

    Current electrical system:
    15 year old but barely used G75F1S Olympian (Caterpillar) generator set, producing 63 kW from natural gas, has instant-on feature in case of power failure. Whole house UPS, which is a daisy chained set of Eaton 9170+ units, good for 18kva in the base unit and maybe another 6kva in the attached unit, the second piece which has been unused for a while due to battery failure (and at $500 per battery x 12 batteries I'm not replacing them until I have to). 200, possibly 400 but I'm not brave enough to poke it with an ammeter, amp service - largest residential wire I've ever seen - into two main breaker panels, which chains to 2 more panels in the room with the UPS, which also has the home network, home entertainment center (what's left of it anyway), and the overbuilt commercial grade phone, lighting, and security systems.

    All in my house consumes about 40,000 kwh annually after my tweaks, which is probably about 30% to 50% of what it used to consume. I've got a goal to bring it down to 20,000 by next year - I've bought the eMonitor software over the weekend to start monitoring exactly where this energy is spent and to cut it back further over the coming months.

    Recently I discovered that my backup generator isn't running. Pretty sure it's from disuse (this has happened in the past). However, since it's a commercial unit and I'm in a smallish town without much industry, the closest repair guy is 2 hours away and charges a few hundred dollars per hour, so I'm in for almost $1,000 before he even starts looking at it. Couple that with the high cost UPS and the fact I want newer / cheaper tech and don't need that kind of power, and would prefer a more green solution all else being equal, I'm pretty motivated to explore a solar panel + battery, such as powerwall, solution.

    There are a lot of factors which make this a poor financial decision: big house, big KWH requirement, energy prices are very stable for past 10 years and relatively reasonable. However, I have to believe there must be some potential offsets to explore, either because the house is already wired to work with a generator and batteries, or perhaps I can sell the UPS and generator (still on the market for sale at about ~$50k if you bought them new, so maybe worth $10k - $20k now?) to offset the cost of a solar system.

    Where can I start to figure this puzzle out? Any tips?

    I have linked up with the local solar community at the nearby college and will be talking in local installers in 2 weeks, but I want to be armed with knowledge and want to understand what I might be able to do with my existing generator / UPS before I have those meetings.

    Thanks!!


  • #2
    Hello 2tall4economy and welcome to Solar Panel Talk

    A solar Grid Tie system ROI varies across the country but will eventually pay for itself.

    If your are looking for emergency power a generator will still be the best bang for your buck even if you get many long term outages. Other forms of emergency power supplies just cost too damn much and IMO (like the Powerwall 2) are still in the beta stage. So based on the current costs of batteries the ROI is extremely long for any place other than Hawaii or Germany.

    Also the best way to save on your electric bill is to conserve and reduce your usage. That is way cheaper then installing any other power generating equipment with much faster ROI.

    Comment


    • #3
      Originally posted by SunEagle View Post
      Also the best way to save on your electric bill is to conserve and reduce your usage. That is way cheaper then installing any other power generating equipment with much faster ROI.
      Best ROI around. Instant savings to boot.

      OP: At 40,000 kWh/yr., you need a serious energy conservation intervention. Where in upstate NY ? zip ? Nice weather huh ? Take this from someone who lived in 13021/14221 for 45 + years: Conservation measures/use reduction in your climate is way more cost effective than anything else, particularly solar generation measures.

      Comment


      • #4
        Originally posted by J.P.M. View Post
        OP: At 40,000 kWh/yr., you need a serious energy conservation intervention. Where in upstate NY ? zip ? Nice weather huh ? Take this from someone who lived in 13021/14221 for 45 + years: Conservation measures/use reduction in your climate is way more cost effective than anything else, particularly solar generation measures.
        Originally posted by SunEagle View Post
        Also the best way to save on your electric bill is to conserve and reduce your usage. That is way cheaper then installing any other power generating equipment with much faster ROI.
        Couldn't agree more - that's why I bought the eMonitoring software (SiteSage 44). $1,000 but I bet I'll get that back in 6-12 months. It arrives next week.

        Already cut the cord, replaced all the lightbulbs with LED and swapped out tons of entertainment system stuff. And we have no living room devices (xbox/vcr/cable), desktop computers, or other "typical" high usage things. I'm guessing it's the things I can't see / don't use (like the commercial phone system) and I'll be able to use the tool to find the circuit they are on and kill those leeches.

        Comment


        • #5
          Originally posted by 2tall4economy View Post



          Couldn't agree more - that's why I bought the eMonitoring software (SiteSage 44). $1,000 but I bet I'll get that back in 6-12 months. It arrives next week.

          Already cut the cord, replaced all the lightbulbs with LED and swapped out tons of entertainment system stuff. And we have no living room devices (xbox/vcr/cable), desktop computers, or other "typical" high usage things. I'm guessing it's the things I can't see / don't use (like the commercial phone system) and I'll be able to use the tool to find the circuit they are on and kill those leeches.
          All the stuff you mention is a start but may be small potatoes in the energy use dept. compared to HVAC and hot water loads. How's the weatherstripping ? insulation levels ? HVAC equipment ? Hope you're not heating w/electricity.

          By way of some rough comparison of your use, the U.S. average per yr. residential kWh use is something like 12,000 or so.

          Comment


          • #6
            Originally posted by J.P.M. View Post

            All the stuff you mention is a start but may be small potatoes in the energy use dept. compared to HVAC and hot water loads. How's the weatherstripping ? insulation levels ? HVAC equipment ? Hope you're not heating w/electricity.

            By way of some rough comparison of your use, the U.S. average per yr. residential kWh use is something like 12,000 or so.

            Yeah, I was reading 2x-4x normal levels which is why I freaked out and started looking at alternatives to the genset. HVAC is baseboard hot water nat gas heating, pipes are insulated, supplemented by net gas furnace which almost never goes on, and AC in the summer (with the hot water switched off). Insulation feels quite good (lowest draft house I've ever lived in). Appliances are all energy star. That's why I'm scratching my head and bought the monitoring software. I'm guessing (hoping?) there is a big leech or two out there (UPS, phone system, lighting system?) etc. If I can't find enough I'll pay the $400 to get the home audit done.

            Comment


            • #7
              sale price for a broken/non working backup genset = $crap value

              PowerWall to run your house, might last you a half hour, After all the ad hype, they are really a pretty small battery bank, power wise. You will need several , maybe a dozen,

              Do you NEED a UPS for the whole house, or just for the computer? Can you "get by" for 10 minutes before starting the behemoth generator you have, 63Kw is pretty darn huge. Most houses would be fine with 15Kw.

              Solar as a backup. When that ice storm comes and knocks the poles down, what will it do to your tempered glass PV array? PV can't take a resin lawn chair at 30 mph if you have winds blowing debris around. If you have conditions that solar would survive and if the clouds clear, solar & batteries could work.

              20,000 KWh year = 55Kwh per day, To get that down from 40,000Kwh is going to be tough, Even 55Kwh daily is going to be real tough, that's going to take at least 14Kw of PV panels.
              Batteries are a never ending expense, every 5-8 years, and 55Kwh will need a LOT of batteries.

              And with your gas appliances, your loads are quite puzzling. 12 Keg coolers in the garage ? Heater relay stuck ON in the heat pump ? Water pump for fountain ?
              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

              Comment


              • #8
                Definitely time to go on a hard core circuit by circuit search for power use. The best investment is to reduce your power use hands down. I would look at your water usage and your well pump. A small continuous leak can really suck up the watts if its deep well pump. Your power bills are going be a drag on the budget month by month so you need to really spend your time on this. The other possible power suck is air conditioning. There are some real bone headed home designs out there where folks went way overboard on glass, they freeze in the winter and broil in the summer so they need hard core AC in the summer to overcome the thermal load. The views out the window may be great but they come with big cost. I saw a rural vacation home in my area that someone got for a "deal" . It had a daylight basement with 2 1/2 story cathedral ceiling great room with basement floor to ceiling glass with great view. They didn't have to worry about solar gain as the glass wall faced north (in northern NH). They wondered why there was 550 gallons of heating oil tanks in the basement.

                Unless you have critical loads like 24/7 medical equipment no need for batteries. If the incentives are good in NY, you could install a Grid Tied system with a SMA string inverter that has a SPS (secure power supply) it has a very limited backup power capacity thrown in for free.

                If the old generator is a quality brand there is market for it as I expect some hobbyist can probably fix it. They aren't going to pay much but will save the dump run. Put it on craigslist.

                Comment


                • #9
                  Originally posted by Mike90250 View Post


                  And with your gas appliances, your loads are quite puzzling. 12 Keg coolers in the garage ? Heater relay stuck ON in the heat pump ? Water pump for fountain ?

                  Neighbors tapping into your wiring for an indoor pot farm?
                  2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                  Comment


                  • #10
                    Originally posted by littleharbor View Post


                    Neighbors tapping into your wiring for an indoor pot farm?
                    Originally posted by Mike90250 View Post
                    12 Keg coolers in the garage ? Heater relay stuck ON in the heat pump ? Water pump for fountain ?
                    I hope it's one of the above so I can shut it off next week

                    I'll report back my findings. Very excited, can't wait for it to arrive.

                    Comment


                    • #11
                      Small update here:

                      Bought a Sense and a Smappee, (and a SiteSage before that - but sent it back since they want $1,200 for a weaker product than the other two which cost $300 or so) both of which claim to monitor your main into the house and identify devices.

                      I get to use them for ~3 weeks but then need to send one or the other back to Amazon and get my money back.

                      So far I've seen that my home consumes about 20 to 25 kwh per day, or about $2 - $2.50. No idea why my bill is $5,500 vs $700. but then again I haven't seen a weekend consumption yet.

                      I monitored one of my 4 panels and discovered it consumes ~410 W pretty much always (it's my security and networking panel) and therefore about $350/yr. Found 2 things on that panel I can switch off. Still, $350 out of $5,500 means there's a lot left to find.

                      My initial reaction is that there is some massive vampire out there which I can't find. Will keep looking.

                      Also went to a local solar community meeting and met with 3 companies. Waiting for their quotes to go solar and battery vs gen. They are really negative towards whole house batteries. Unexpected...
                      Last edited by 2tall4economy; 03-09-2017, 11:10 PM.

                      Comment


                      • #12
                        Your Topic Title is Moronic. If solar and battery were better, pros would do that. Fact is no pro would ever do that.Generator/UPS is far less expensive, more reliable, and same unrestricted power of the utility.
                        MSEE, PE

                        Comment


                        • #13
                          Originally posted by Sunking View Post
                          Your Topic Title is Moronic. If solar and battery were better, pros would do that. Fact is no pro would ever do that.Generator/UPS is far less expensive, more reliable, and same unrestricted power of the utility.
                          Um, thanks for your input I suppose. I'd argue a battery is better than a nat gas generator that produces 75KW when my peak usage is 4KW and my steady state consumption is 2KW. Wasteful and costly.

                          And as far as the solar goes, yeah probably not required, but if I won't need the generator anyway, might as well sell it and us the money to buy solar panels to save on energy.

                          Comment


                          • #14
                            Keep researching consumption until it is itemized; then make a plan. I managed to cut the electric bill
                            by 2/3 over some years, by many different means. Solar is the worst possible backup; batteries are
                            extremely uneconomical, very limited in capacity, and high maintenance. I eventually managed to
                            generate all home energy with solar; the only batteries here are portable appliances and for starting
                            gasoline engines. A solar array big enough for your present consumption would be 400' long.
                            Bruce Roe

                            Comment


                            • #15
                              Originally posted by 2tall4economy View Post

                              Um, thanks for your input I suppose. I'd argue a battery is better than a nat gas generator that produces 75KW when my peak usage is 4KW and my steady state consumption is 2KW. Wasteful and costly.

                              And as far as the solar goes, yeah probably not required, but if I won't need the generator anyway, might as well sell it and us the money to buy solar panels to save on energy.
                              Why wouldn't you get a smaller generator closer to your consumption load? IMO a battery will cost more to generate a kWh then a fossil fuel generator if the generator is matched to the load usage. Especially if the generator is used only a few times a year. That is because the battery continues to die if it is being used or just sitting there while the generator can sit for a long time and still have much more life to give.

                              If you don't believe me then I would say size up your solar / battery system and provide a price. Then calculate it out as to how many kWh the batteries will provide over their true life time. Divide that number into the cost of the system. You will most certainly get a higher $/kWh then the cost of a generator and fuel that provides the same number of kWhs even at an elevated cost of fuel.

                              I get it that some people don't like the noise and smell of a fossil fuel generator. I also get it that some don't like the idea of putting CO2 up into the air. But what I don't get is that some people still believe that a solar/battery system is cheaper to run as an Emergency backup power supply then a properly sized and designed fossil fueled generator.

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