Calculation of needed energy for a small house

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  • Pollux
    Junior Member
    • Apr 2015
    • 6
    #1

    Calculation of needed energy for a small house

    Hi,

    I am trying to size an off-grid system for a small home in a remote area (with no grid availability).

    I got stuck right at the beginning: calculating the energy needs.

    I have made an inventory of all installed electrical equipment in the house, power and hours of functioning.
    After finishing it seems heavily over sized.
    I believe I overestimated the hours of functioning, or I should have taken into account some simultaneity factor.

    Please find attached a .csv file containing this inventory. (I renamed it TXT because for some reason CSV/XLS are not allowed by the forum. Please do the reverse naming and open with an Excel-like software.)

    Please tell me your opinion.

    xcalcul.txt
    Tags: None
    • Sunking
      Solar Fanatic
      • Feb 2010
      • 23301
      #2
      Looks good to me. 15.2 Kwh per day is a tiny little house. I hope you are a very wealthy person as that is going to cost you around $40,000 initially to install and $17,000 to $20,000 every 5 years to replace batteries.

      Good luck with that.
      MSEE, PE

        Comment

        • Mike90250
          Moderator
          • May 2009
          • 16020
          #3
          You are going to change your lifestyle, or spend a LOT of money.

          I'm in a well designed 2,200sf house and pump water for 2 hours a day and generally burn about 10-2KWh
          (2 fridges, deep freeze, couple laptop computers) and I run a 5kw array and had >200 generator hours Nov-Jan this last fall
          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

            • Raul
              Solar Fanatic
              • May 2015
              • 258
              #4
              Hi Polux and welcome to the forum.
              I also have a log cabin on the upper chain of the Carpathian Mountains and I will be installing a small system this summer; currently it gets a live bench test on my workshop in London .
              I would never contemplate running those apliances you listed there from solar.
              There is cheap bottled gas in Romania and that's what we use for heating ,cooking , dhw and coffe making.
              The only thing we will be running of solar would be: fridge/freezer a+++ rated; top load camping washing machine, small travel iron; lighting; TV ; laptop; propane boiler ( ign) & ( circulating pump) and a small microwave 20mins top. We also got a Honda genny for back up.
              We go there to relax and keep gadgets to minimum .

                Comment

                • lkruper
                  Solar Fanatic
                  • May 2015
                  • 892
                  #5
                  Originally posted by Raul
                  Hi Polux and welcome to the forum.
                  I also have a log cabin on the upper chain of the Carpathian Mountains and I will be installing a small system this summer; currently it gets a live bench test on my workshop in London .
                  I would never contemplate running those apliances you listed there from solar.
                  There is cheap bottled gas in Romania and that's what we use for heating ,cooking , dhw and coffe making.
                  The only thing we will be running of solar would be: fridge/freezer a+++ rated; top load camping washing machine, small travel iron; lighting; TV ; laptop; propane boiler ( ign) & ( circulating pump) and a small microwave 20mins top. We also got a Honda genny for back up.
                  We go there to relax and keep gadgets to minimum .
                  What brand/model of washing machine?

                    Comment

                    • Raul
                      Solar Fanatic
                      • May 2015
                      • 258
                      #6
                      Mine is unbranded 230w washing power , twin tub . It's the same as Swiss one; one concept ; hiffi and the like. I found them on eBay UK and you can find them in U.S. as well but only seen the single tub . The twin makes life easy to rinse dry and has the added bonus of a draining pump so I can plumb it in and not fuff about.

                        Comment

                        • Pollux
                          Junior Member
                          • Apr 2015
                          • 6
                          #7
                          thank you all for your feed-back.

                          it's not really a project that I want to implement. it's more like an exercise, to understand what are the do's and don'ts with PV systems.

                          If I eliminate from the list the water boiler, cooking machine, air-conditioning and infrared heating panels, it remains a 5 kWp system. which is realistic for a small house...

                          the heating and hot water can be done with wooden pellets, the cooking with gas, and one can do without air-conditioning...

                            Comment

                            • Mike90250
                              Moderator
                              • May 2009
                              • 16020
                              #8
                              Originally posted by Pollux
                              .....the heating and hot water can be done with wooden pellets......
                              Be sure to include the power required by the pellet stove:
                              Auger motor
                              Blower motor
                              Ignitor glow coil (can be close to 400 watts, at all times the heater is on)
                              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

                                • Pollux
                                  Junior Member
                                  • Apr 2015
                                  • 6
                                  #9
                                  Originally posted by Mike90250
                                  Be sure to include the power required by the pellet stove:
                                  Auger motor
                                  Blower motor
                                  Ignitor glow coil (can be close to 400 watts, at all times the heater is on)
                                  right!
                                  thank you!

                                    Comment

                                    • Pollux
                                      Junior Member
                                      • Apr 2015
                                      • 6
                                      #10
                                      Hi,

                                      I have done the calculation and electrical diagram for a 6 kW PV system.

                                      It is a hybrid system, including battery bank, generator and grid connection.
                                      Of course, I realize this is not realistic for most cases, but I intended only to do a dimensioning exercise not a real-life application.

                                      My main concern is about the chargers and controllers. I use a Conext XW6048/230/50 inverter and two Conext MPPT 80/600 charge controllers. In the Schneider catalogue for the inverter it says "inverter/charger", so I'm not sure I should use the MPPT chargers at all.
                                      I have chosen 2 MPPT 80/600 chargers, but I'm not really sure if two smaller MPPT 60/150 would do for this application.

                                      Please review it and tell me what bugs you find in it, or other suggestions.

                                      6kw_PV_system.pdf

                                      Thank you!

                                        Comment

                                        • Pollux
                                          Junior Member
                                          • Apr 2015
                                          • 6
                                          #11
                                          Hi,

                                          I have asked technical support from Schneider Electric regarding the usage of the chargers.
                                          Now I think my design is pretty much ok, although a better configuration would be using two MPPT 60 150 chargers... I will work that out...

                                            Comment

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