Generator: "To be, or not to be...that is the question!"

Howdy folks,

I am just finishing up building a small Rammed Earth casita (cabin) of 640 sqft.
It has a bathroom, bedroom, kitchen/living room.

My wife and I plan to use it only on weekends for the next three years.
We will then move into it while we build our 'main' house. This casita will then become a mother-in-law-quarters.

Grid power is 3 miles away, hence we will eventually be living on 100% Solar Power.

  1. I am thinking that I should just use a generator during the weekends for the next 3 years? Or should I just go ahead and spend the money for a complete Solar set-up now?
  2. Would the Solar equipment depreciate appreciably in those 3 years and would it be somewhat 'outdated' 3 years later?
  3. If I do end up going with a generator, should I still consider using batteries, etc., or would that cost not be worth it at this point?

Thank you ahead of time folks.
I am sure I will have a follow-up question.

Tombstone, AZ


  • BB.BB. Super Moderators, Administrators Posts: 29,994 admin
    Re: Generator: "To be, or not to be...that is the question!"

    So much depends on your approach to design and energy usage... Grid Power (and solar Grid Tied systems) cost around $0.15 to $0.35 per kWhr (excluding the costs to run the lines three miles)... A full off grid system (and generators too) probably runs more in the $1.00 per kWhr price range (and off grid systems are generally not allowed with state and federal rebates/tax breaks).

    Your first rule of thumb is to conserve electrical usage...

    Try only use "expensive" electricity were absolutely needed... Electronics, lights, fans, pumping... Use Solar Thermal for hot water/heating. Your number one energy user is probably the fridge/freezer... If you can live on propane powered ones for now, may not be a bad idea.

    Solar panels are best used when the the power is used all year long--in your case, you could design a system so that the batteries will last you 2-3 days without sun, but use smaller panels that would take 7 days to charge your 2 days of battery usage (save money on panels for now).

    With off-grid, you will still need a generator for bad weather conditions--so you will still have the cost of a generator even with a solar--just saving the cost of fuel when using solar (which is not a bad thing).

    At this time, the panels and electronics seem to be relatively flat in pricing--there is still good demand and the products (inverters, charge controllers) are mature and not too expensive. They don't wear so if you buy them now, they will still be useful 3 years from now.

    The batteries though, do age and will last you from 3-10+ years (depending on quality, price, and maintenance).

    If you power usage is not high, just buying a Honda eu2000i generator (~$900 if you look around) (1,600 watts continuous) will run ~400 watts for 15 hours on 1.1 gallons of fuel (factory spec.). Run the generator for 4 hours in the morning and 4 hours in the evening, you can run a fridge, lights, small pump, fan, TV on probably 1.5 gallons of fuel a weekend. Get a small storage battery and charger and you can have 12 vdc radio and LED lighting for times when the generator is not running... Low initial costs, not leaving a lot of expensive equipment where it can be stolen/lost/burned...

    However, if you are eventually going to get into full solar off-grid living, it would probably not be a bad idea to set up the system right now. It will give you actual data on how much power you use and how much the system can generate for your area (for a given solar array). Get good (not cheap) panels, charge controller, battery monitor, and true sine wave inverter, and get cheap flooded cell "golf cart" batteries and start learning...

    After 3 years of running off grid--you will be in a much better position to buy/build your next system for the main house--plus you will still have the small system for the in-law unit.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Generator: "To be, or not to be...that is the question!"

    Hi I was in a similar position as you a a couple of years ago when I bought my barn in Spain, although I wasnt visiting every weekend I was out for varying periods over the next two years till we finally emigrated. I endorse everything in the previous post, I started off with no solar first visit and started with a 1.6 kw suitcase genny charging a inexpensive 24 volt 330 amp hour set of 6 12volt lesiure batteries through a Modified Sinewave Xantrex DR2424E inverter bought secondhand off ebay. This allowed me to run a fridge freezer 24/7 a small TV and satellite system and water pump on about 4 hours runtime a day through the inverter. I also carried my genny around my site to power stuff like my cement mixer. So IMHO running just a genny every time you need power will become annoying and costly and impractical . I moved out to the countryside for peace and quiet not to listen to a genny running all the time! Trust me it wont take you long to get fed up of just a genny for power!

    Second vistit I had bought 3 x 200 watt solar panels and a basic Xantrex C40 charge controller and added this to the system which in the summer cut my genset runtime down to nothing.

    The modified sinewave inverter did fry a couple of phone chargers and a dewalt battery charger over the next year and I learnt to use these items only when the genny was providing power. I have now upgraded to a full sinewave SW3024E inverter charger added another C40 charge controller and gone up to 1600 watts installed PV with more to add. So if you can afford it go for a sinewave inverter if you can. But I was also concerned over security whilst I was still living in Uk and didnt want to leave expensive equipment unattended !

    The points I would mention are that I sold my Dr2424E and small lesiure battery bank on to friend in a similar start up position at cost ie I made no loss or profit 2 years on, with 3 years of hindsight and living off grid completely for the last year I wished Id upgraded to a 48v base system for full time off gridding as this would have saved money on wiring costs and charge controller costs.and allowed a bigger single string battery bank. I kept the little suitcase genny as its a emergency backup to our larger main generator and still good for portable power around our small holding . I will upgrade my C40s to MPPT soon and the C40s will be sold on,probably at a little profit !

    As the PV side is a very modular setup I would recomend spending a little bit extra on your first charge controller controller go MPPT and go 60 amp and this will allow you to fit panels as and when you can afford them without upgrading the controller ! Go 48v base voltage from day 1 it will save you in the long term and if you go the outback inverter route you can start with one inverter and easily expand it when your power needs go passed weekend warrior to full time off gridder. Also a subscripton to Home Power Magazine IMHO is good value for money. HTH

    PS According to NAWS PV Panels have increased 25% in price over the last three years in USA so it would seem the earlier you buy will save you money and spend less on fossil fuels.

    Have a look at my setup
  • mike95490mike95490 Solar Expert Posts: 8,579 ✭✭✭✭✭
    Re: Generator: "To be, or not to be...that is the question!"

    What is security like in the construction zone, will generators walk away? solar panels still be there next month ? Batteries ?

    Leave them locked inside till you arrive, stack outside to recharge over weekend, and lock up when you leave. Maybe after the roof is up, you can attach panels permanently.
    Powerfab top of pole PV mount | 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

    gen: ,

  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Generator: "To be, or not to be...that is the question!"

    While my crystal ball can be fogged with the best of them, In US dollars, I don't see any reason solar panels, the electronics or batteries will cost less or lose value in the next 10 years.

    On the Electronics, there is nothing technology wise that would allow any mentionable cost savings on the horizon, Batterys, the lead is in VERY short supply and would take a decade to have a surplus and the solar panels are being made in other countrys and any devaluation of the US dollar will offset any price reductions due to the increase in solar panels supplies.

    I would build the perminate solar system now that will power the final home, not just the inlaw cabin and have it available for the building of the main home.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Generator: "To be, or not to be...that is the question!"

    I have to agree with every thing BB said. I would look very carefully at the load side first. It is amazing how low you can get your loads, especialy on a week end house. (We use between 25-35amp/hours day 12vdc.)

    You will need a generator anyway, so the idea of a Honda eu is perfect. I have a eu 1000 that runs my xantrex charger full bore, while the generator idles.

    My only concern would be the batteries. If they are going to be idle for long periods and then not really used for 3 years, you might think about a small expandable pv system, with just a small set of batteries for your weekend use now. Having a big bank sitting around for three years waiting to be used is not a good idea, in my mind.

    Keep in mind that using other fuels for big loads, can bring down the size of the pv array as well as the battery bank. We pump water once a day using a gasoline pump to a gravity tank. We use 2 litre of gas a month to do so. Exanding the array to fill this load would be comparativly expensive, even with $1.25/litre gas. Same with the washing machine. A honda powered wringer washing machine cost us about 1 litre a month. To up size the battery to carry a washing machine load would be expensive. Same with the Fridge. Even the simple Dometic fridges, running on propane are cheap to run. our fridge will run for 6 months on a 100# propane tank.

    Good luck,

    I carus
Sign In or Register to comment.