Not Sure how to start off

Lake_ManLake_Man Solar Expert Posts: 27
G'day forum,

quick question - how do i start planning a solar off grid system if i am not sure of the loads i will have? Could i possibly work backwards by designing the system around the size of the battery bank?

The property is in a very remote location wit little to no chance of ever seeing grid power. We are in a very good solar area according to the solar charts I've looked up. We do however have a rainy season that runs from November to May - so a good percentage of overcast days here and there - but also lots of clear days during this period.

I am looking at a 48V system with 2000amps of battery capacity. Strongly considering the HUP SOLAR ONE batteries - 2000amp/Hr C20 rate at 48V. Thats a big battery bank as most of you would well understand. I am also planning two gensets - a 60Kva and a 15Kva genny - so i have a backup genny for one the first one goes down - this place is REMOTE so we need to have plan B and Plan C in place for when the inevitable happens and a gen set goes down. I will need the big genset to put enough power into the battery bank and the small one for small light loads when there is no need to top up the batteries (ie middle of the day when panels are in full swing charging and i need to power an electric stove/kettle/washing machine/clothes drier etc - and no we cant hang cloths out to dry in the sun because of a small parasite here that lays eggs on wet clothes and then when you wear then the parasite egg burrows into your skin and incubates, hatches into a worm first then a moth and eventually causes a huge sore as the moth gets out of your body to go reproduce - scary stuff huh). So we have all these unique things to think about. God only knows how the pioneers managed to live here !

So anyway, i cant accurately work out my loads - a guess at best. Two fridges, two freezers (for when one goes down - costs a fortune to get fresh food out here so cant risk losing all our meats etc because a freezer goes down), lights, 4 computers, monitors x plenty ...it goes on and on. In fact i am considering 2 x 2000 amp/Hr @48v battery banks.

So given all this how do i even begin to plan how many panels? the only thing i can come up with is how many panels needed to charge the batteries as some sort of guide.

Ideas? Am i thinking this through properly? Any comments most welcome.

Have a great day.

P.S the reason i cant work out loads is we take possession of the property on Jan 1st 2013 (we just bought the place). As well this is a small lodge and has 7 guest chalets - so hard to know what guests may want to plug in while there for a week - we are new to the lodge business so have no prior experience as to what the guests may want to plug in.....laptop/camera for example, as for any thing else.......who knows ?

LM

Comments

  • vtmapsvtmaps ✭✭✭✭ Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Not Sure how to start off
    Lake_Man wrote: »
    quick question - how do i start planning a solar off grid system if i am not sure of the loads i will have? Could i possibly work backwards by designing the system around the size of the battery bank?

    If you need to buy a pickup truck, you need to know the load you want to carry. If you buy a half-ton pickup you cannot convert it to a one-ton pickup when you realize your mistake. Likewise, it is very difficult to upgrade an undersized off-grid system.

    Sure, you can design backwards: buy the half-ton truck and cut your loads in half to fit.
    i need to power an electric stove/kettle/washing machine/clothes drier etc
    How about propane? It is not reasonable to try to power an electric stove or clothes dryer with batteries.
    and no we cant hang cloths out to dry in the sun because of a small parasite here that lays eggs on wet clothes and then when you wear then the parasite egg burrows into your skin and incubates, hatches into a worm first then a moth and eventually causes a huge sore as the moth gets out of your body to go reproduce
    Where is this place?!?! I don't think I want to go there while I'm still alive.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • HiminsHimins ✭✭✭✭ Solar Expert Posts: 54 ✭✭✭✭
    Re: Not Sure how to start off

    I would most certianly consider some additional passive solar. A friend built a very nice comercial installation passive solar heat for water, forced air, and under floor heat. This could naturally be used for drying clothes. You didn't mention climate or your water source. But looking at the overall size of your needs, and future needs, you may need consider wind, hydro electric, wood heat, geo-thermal, etc... I would LOVE LOVE LOVE, to review the natural resourses you may have sitting on this property already. My farm has been off grid since the spring of this year and I am constantly suprised by all the ways to supply my basic needs with some inovative(usually old) tech. Then you didn't mention a budget. You may have to include that in your overall plan. I had many customers ask me for a bid in my business, I always told them I need to know their budget before hand, then form a scope of work using the funds available. Unless you plan to grow and sell a lot of rope!
  • CariboocootCariboocoot ✭✭ Banned Posts: 17,615 ✭✭
    Re: Not Sure how to start off

    Can you work backwards? Sure! Start by buying the back-up generator you're going to need when you run out of power because the loads are heavier than anticipated and the solar not as much. And a big bottle of aspirin. Trust me; seems I spend half my time helping folk who have run into that problem.

    Guest cabins are going to be trouble. When we turn the cabin over to the kids for a couple of weeks in Summer ... oh boy. I cranked the LVD up on the inverter just to make sure the 'frige stays running over night. :roll:

    Refrigerators and freezers are big power users. They have heavy start-up surges and will easily suck down 1 to 2 kW hours per day each. I would suggest you work up some sort of allotment for power, no matter if it is a calculated estimate or from real Kill-A-Watt meter readings. I would also suggest that instead of one big system you plan two or three smaller, independent systems. That way if one fails you can still keep things running until repairs can be made.

    Without some kind of Watt hour target you are shooting in the dark. You need that number to size the battery bank properly. The size of the battery bank determines how much array you need to recharge it. In the case of your suggested 2000 Amp hour 48 Volt battery bank (massive) you would have about 12.5 kW of panel and three charge controllers. Such a system, btw, would supply about 24 kW hours of power per day - which is as much as a typical on-grid house.
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Not Sure how to start off

    Yes, you can work backwards--Here how I would start:

    First, if you pick the size of battery bank, then you want to charge at 5% to 13% rate of charge (just starting rules of thumb, don't recommend going smaller, and you can go upwards of 25% rate of charge--But that is expensive and can be a waste of solar resources--batteries get charged in the morning and rest of day just sit at float charge--and losing energy from sun... Note if you have lots of mid-day loads--washing cloths, fridge/freezers, pumping water, using solar for cooking, etc., you can up the solar array if you wish--below assumes you charge during day, use power at night):
    • 2,000 AH * 59 volts charging * 1/0.77 panel+controller derate * 0.05 rate of charge = 7,662 watt array minimum
    • 2,000 AH * 59 volts charging * 1/0.77 panel+controller derate * 0.05 rate of charge = 15,325 watt array nominal
    • 2,000 AH * 59 volts charging * 1/0.77 panel+controller derate * 0.05 rate of charge = 19,922 watt array "cost effective maximum"

    For your needs, I would suggest the 10% / 15,325 watt array... A charge controller would need, at a minimum to be rated at:
    • 15,325 Watt * 0.77 derating * 1/59 volts charging = 200 amps minimum solar charge controller rating

    Generator sizing--Generators are most fuel efficient (in general--especially gasoline/petrol/propane powered engines) at 50% or higher of rated output... Put a large genset with a small battery charger--And you can waste a lot of fuel... Also, diesel generators should be operated at 40-60% minimum rated output for long life ("wet stack", carbon buildup, glazed cylinder walls are all symptoms of running too light of loads on a diesel genset).

    And, you need to understand the AC battery charger you will be using... Many (most?) battery chargers have pretty poor "power factor" -- Typically in the 0.67 range... What does this mean? Basically, it is how "efficiently" the AC charger (or any AC load) uses the current. Many loads have a non-sinewave current wave form, or take the current out of phase with the voltage wave form--Makes the load take "more current" that would be expected from the power equation:
    • Power = Volts * Current ("normal" power equation)
    • Power = Volts * Current * Cosine (current lead/lag) = Volts * Current * PF

    So, with inverters and gensets, they have both a Watt and a Volt*Amp (VA) rating...

    More or less, you have to plan the solar array and battery bank to supply Watts and Watts*Hours; and plan the inverter and genset to supply VA (kVA, etc.)... It is because the wiring/inverter/genset have to be designed to supply the extra current to poor PF loads. Smaller inverters and gensets have Watts=VA max ratings... Larger commercial gensets may have VA>Watt maximum rating--So you need to keep both numbers in mind when doing the design.

    For example, your 15kW genset--If the genset is designed for 15kW/15kVA rating, then the maximum battery charger current output would be:
    • 15,000 Watt * 0.67 PF * 0.80 Charger Eff * 1/59 volts = 136 Amps @ 48 volt bank (typical battery charger)
    • 15,000 Watt * 0.95 PF * 0.90 Charger Eff * 1/59 volts = 217 Amps @ 48 volt bank (very efficient battery charger)

    If your genset has a kW rating of 15,000 watts and a kVA rating of 22.4 kVA, then you need to do both calculations and use the "worse case" numbers for sizing the charge controller:
    • 15,000 Watt * 0.80 Charger Eff * 1/59 volts = 203 Amps @ 48 volt bank (typical battery charger)
    • 22,400 VA * 0.67 PF * 0.80 Charger Eff * 1/59 volts = 203 Amps @ 48 volt bank (typical battery charger using PF & VA ratings)

    So--Now how much sun do you get in your area (this is not the UK--right?)? Lets assume that your minimum is 3 hours a day (sunny weather in winter) and >4 hours of sun per day for 9 months of the year (basically your solar break even point). Many locations can get 5-6+ hours of sun per day--Handy if you have lots of refrigeration (use more power as temperatures rise) and/or air conditioning in a great room.

    So, using 4 hours of sun and your "10%" rated array (minimum expected good weather energy):
    • 15,325 Watt array * 0.52 overall system eff * 4 hours of sun = 31,872 WH = 31.9 kWH per day [fixed]

    Note, I am using lots of digits for the calculations so you can follow my math and avoid introducing more errors--But in reality, if your solar is within 10-20% of the above numbers--That is doing pretty good.

    Also, this is a pretty big system--On the forum here, we try to educate folks so they can understand the basics (power, conservation, basic power/solar power math, and hardware)--This is probably a system that is beyond the capabilities of a first time solar power user to design and install themselves unless they have a technical/power background (retired licensed electrician, etc.).

    When you get systems this large, you are dealing with some pretty scary energy levels (huge current from battery bank if there is a short circuit, properly crimping wire connections, very large diameter copper wiring, fuse/breaker panels, etc.). High energy Arc Flash burns are very serious and the risk should not be taken lightly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot ✭✭ Banned Posts: 17,615 ✭✭
    Re: Not Sure how to start off

    Bill;

    About that PF of 0.67 for chargers - do you know what charger/type this is? Part of a continuing discussion in various threads is about Outback's chargers not be PF corrected like Magnum and yet in real-world performance we are not seeing any big problem.

    If I can remember this until I get back next year I'll try measuring it at different charge levels, but the one time I did check it was 0.99 at full rate (25 Amps to the batteries which is not the maximum output of the charger by far but is correct for my bank).

    I'd hate to think people are seeing this as a potential issue if it isn't really. Possibly the poor PF is on stand-alone chargers?
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Not Sure how to start off

    Marc,

    As I recall, that was with Iota and similar chargers.

    In general, if the mfg. does not say they have PFC (power factor correction), then they usually do not.

    There are some cases where the charge controllers can have good PF near rated output and have poor PF a light loads (Induction Motors have similar properties--As I recall). I thought I had read a thread in the Outback forum where this was true (or somewhat true?) for the Radian (--but I could be wrong--could not quickly find the thread).

    The Inverter/Charger units seem to have better PF than stand alone chargers (and much more programmable too).

    Power Factor Corrected stand alone battery chargers seem to be few and far between--At least that was what would found in this thread:

    Question about battery charger selection with EU2000 generator.


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot ✭✭ Banned Posts: 17,615 ✭✭
    Re: Not Sure how to start off

    That's about what I thought, Bill; just because an inverter-charger doesn't say "power factor corrected charger" doesn't mean it has a poor PF. I am not surprised at the stand-alone units being low PF as I have seen inside many battery chargers and some of them just leave you shaking your head. :roll:

    Naturally with any charger, especially an inverter-charger, some power has to go to running it which is subtracted from the input power available for charging.
  • vtmapsvtmaps ✭✭✭✭ Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Not Sure how to start off
    BB. wrote: »
    Power Factor Corrected stand alone battery chargers seem to be few and far between

    Actually I have in my research, found quite a few. In the forklift world of commercial warehouses, they must use pf corrected equipment, and there are quite a few pf corrected chargers on the market. The problem is that they don't follow the charging profiles that we are accustomed to, and most (not all) of them do not have user adjustable charging parameters. It's not clear (to me, at least) how these chargers would interact with wind or solar chargers.

    Of course, there is the Meanwell charger referred to in the honda thread. Xantrex also makes a Truecharge2 line of pf corrected chargers.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Not Sure how to start off

    I am glad to hear the commercial fork lift chargers are power factor corrected... I would think they would have to be PFC (from the various requirements I had to design larger computer systems to meet).

    A couple years ago, I cruised the web looking for PFC fork lift chargers and really did not find much on the subject at all... Perhaps if they "all have it", they it is no longer a bullet point on the glossy.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off

    Wow - great information. That's what i love about this forum, deep detailed information and a good discussion all round !

    Location of the property in question is 9 degrees South of the equator in the middle of Africa. Solar charts show very good level of solar ...mmm what do you call it? Solar....intensity? So that's good.

    Propane (LPG?) is available, is very expensive, is subject to shortages at various times through the year and the nearest re-suppply is 1200Klms away. All in all not very practical. We are going to use gas for cooking - plan will be to buy 7 or 8 LARGE gas cylinders so that we always have 2 full cylinders on standby, 2 for use and the rest in various places on the way up or down to the lake being refilled and returned for use (its a long supply chain so expect to have cylinders on the back of trucks going up and down for refill). Would not want to use this gas for clothes drying and/or running refrigerators.

    Ambient temperatures are approx 30 degrees C a good deal of the time. we are on a large fresh water lake (in fact this lake holds 15% of the earths fresh water) and the temp of the lake is a constant 26 degrees C so that helps keep temperatures fairly constant through the night as well. Night time gets down to about 20 Degrees C and daytime hits a max of around 40 Degrees C with the average being around 30 degrees C. Heating is not needed for us! Aircon would be lovely !! But at this time i am not planning Aircon - if it turned out we had the power budget for it i would jump at it but its at the bottom of the priority list and not something i have given much, if any thought too at all. We do get a lovely breeze down the lake from late September to end of April - it starts about 9 in the morning and gradually picks up in intensity until about 2-3 PM then dies off such that by about 5PM the air is still. It is a refreshing cool breeze that blows most days all day - so we get some sort of cooling during the hottest parts of the day - natures Aircon? Have considered a turbine but those things are expensive, don't give out so much power, are big and unwieldy, require ongoing maintenance and need constant wind to be of much real use and since our wind is mostly during daylight hours i think solar is a better fit for the money. Could be wrong though! I would not rule wind out per-Se just that from all the reading i have done it seems solar is the better bang for the buck.

    Not sure we have any natural resources apart from Sun, Wind and Water. Its in the rift valley so there is lots of stone either on the surface or just under the surface of the ground. But as said, until you take a close look with an eye towards finding whats there......well need to think that one through abit and just plain LOOK

    Budget is whatever it costs! The less the better! But realistically i am prepared for 100 - 120K+. Batteries per set are going to cost about 25K landed (fortunately we are duty free and sales tax zero rated on all alternative energy related products including batteries for solar use in this country) and i am figuring on 2 sets of batteries. I should think at least 20K on inverters. 60Kva genset is around 20K, the 15Kva genset around 8K. Then panels. How many panels is the $64,0000 question (and i think in this case it IS going to cost $64,000) I can see this hitting 100K+ pretty easily. I'd prefer to spend 20K if i could get away with but i know i cant so......

    The hard part is trying to figure what the REAL loads are going to be. Dont want to put in some massive solar panel farm and not use even half of its output and dont want to put in 50 panels and find we need another 200 later on....shipping and transport is a major cost here so if we need 300 panels best to ship them all in a one container and be done with it. Plus it could be a good idea to keep spare panels in the store room? Expensive yes, but trying to find identical panels 8 years form now might be hard, so........

    One aspect to this is water pumping. We are right on the lake and have several hundred meters of water frontage. There is a water tank in place (needs serious work to make it a lot better but it is in place and usable for now) and i'd figure about 15 - 20 meters above the water surface (from water surface to top of tank inlet). We have large expenses of lawn to keep green so we need to pump large volumes of water just to keep the lawns and the gardens. I know this sounds extravagant but it is a tourist lodge so no real choice here.....i mean do you want to go to a lodge on holidays and be in an area that is dry and brown and dusty?...... so water it is. Sorting out the water pumping is a whole other beast to wrestle. First plan (sure this will change over time but for now at least something to work too) is to put in 4 or 5 x 10,000 liter poly tanks and pump those full with the genset running - lets us charge batteries, freeze the freezers down to -30, get the fridges as cold as they can be, do some baking (cakes, pastries etc for guests) do laundry, mow lawns (electric lawn mowers) and PUMP water. Hence the 60Kva genset i am planning on. I would expect about 2 to 3 hours a day genset run time. The smaller genset would be for times when its been raining all day and batteries are running down a bit lower then i'd like (50% DOD) and we need lights, computers etc on. Would not run heavy loads on the small genset.

    I am definitely in for 1 x 2000 amp/hrs at 48V battery bank. I have a small inverter system running at home here in the capital city of this country. Our Grid supply is TERRIBLE !! Really dirty grubby power that goes off all the time and we are getting a LOT of load shedding as there is a huge power deficit in Southern Africa. There is simply not enough power generation for the EXPLODING population growth here...its scary to look at the projections of the population growth in Africa.....the planet is in trouble...... result of huge population growth and not enough power is....we have the second highest deforestation rate in the world...but this is a whole other debate and not for this discussion. So here at home i have a Victron 48v 5Kva Quatro inverter connected to mains on one side, and 4 x 200 amp/Hr 12v AGM batteries on the other. I've been running this for 3 years now and have come to understand how little power is stored in those batteries! I know that all of you here know it but its frightening how little power is available from off grid systems compared to being on grid!!!! So although this is a small system it has given us insight into batteries and inverters. No panels etc that's true so no experience there. We understand we are in for a whole new learning curve! So i figure at the very very least is 1 x 2000amp/Hr at 48v battery bank. I am seriously considering 2 sets of these. I want a LONG life from these batteries so would not really want to go below 30%DOD if possible, hence spreading the load over 2 sets. Implications to this though as you all understand. First is $$$ but it is what it is - who ever said living in paradise was going to be cheap? The big genset can charge both battery banks with careful control of what is on at any given time (don't want a big BIG genset). The real issue is how many panels do i need to charge up those batteries during our long sunny stretches? We would prefer to use the gensets as little as possible although we do understand there will be genset run time every day. For the record, diesel here is about $6.00 a gallon. We expect this lodge to stay in family hands for another 30 years at least (Children in late teens, early twenties who are VERY keen to go run this place) so the prospect of 30 years of running a generator is not that appealing........... rather make the investment in panels now and be done with it (well as much as one can be done with it anyway)



    Well that is a lot of back ground. Didn't mean to turn this post into a mini novel - sorry for that!

    This is a BIG project for sure. I don't expect to design this off a forum. I am just throwing ideas around and coming up to speed on the lingo you power folks talk. I want to understand al laspects of this project BEFORE i dive in.......ur..as you say around here, Ready Fire Aim? I DON'T want to do that.

    Warm Regards

    LM
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off
    vtmaps wrote: »

    How about propane? It is not reasonable to try to power an electric stove or clothes dryer with batteries.

    Where is this place?!?! I don't think I want to go there while I'm still alive.

    --vtMaps

    Gas is expensive and problematic - we will use it for cooking but the less we use of this stuff the better.

    We are in South Central Africa in the bush. On the edge of a large lake. 1200Klms from the nearest city. Grid power is about 20 Klms away across the water on the other side of the lake!! So close yet so far.

    If you want to know more about the parasites we have to deal with.........

    http://www.health24.com/medical/Condition_centres/777-792-1461-2504,31608.asp

    http://www.tropmed.org/primer/chapter10-2.pdf
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off
    Himins wrote: »
    I would most certianly consider some additional passive solar. A friend built a very nice comercial installation passive solar heat for water, forced air, and under floor heat. This could naturally be used for drying clothes.


    This sounds INTERESTING ! Can you provide more info or a link to where i can start researching this? I am up for any and all ideas. I may not use them all but cant hurt to consider everything and rule nothing out at this stage of planing.

    Thanks for the heads up.
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off
    Can you work backwards? Sure! Start by buying the back-up generator you're going to need when you run out of power because the loads are heavier than anticipated and the solar not as much. And a big bottle of aspirin. Trust me; seems I spend half my time helping folk who have run into that problem.

    I hear Ya !!!!! This is my fear - not understanding the TRUE loads and under/over sizing the system. Plus allow for growth and things we may be doing 5 years from now we have not even thought about right now! Difficult to say the least. Yet to get it wrong = $$$$$ wasted.


    Guest cabins are going to be trouble. When we turn the cabin over to the kids for a couple of weeks in Summer ... oh boy. I cranked the LVD up on the inverter just to make sure the 'frige stays running over night. :roll:

    Got you on that one too. I have no idea what people get up too in thier rooms and what they may try to run....a laptop , a camera, a cell phone (camera function) Ipod/s .....hmm cant think what else.

    Refrigerators and freezers are big power users. They have heavy start-up surges and will easily suck down 1 to 2 kW hours per day each. I would suggest you work up some sort of allotment for power, no matter if it is a calculated estimate or from real Kill-A-Watt meter readings. I would also suggest that instead of one big system you plan two or three smaller, independent systems. That way if one fails you can still keep things running until repairs can be made.

    Yes no way around this - just have to accept they are power hogs and we cant live without them (well....you can be who wants too?)


    Without some kind of Watt hour target you are shooting in the dark. YEP You need that number to size the battery bank properly. The size of the battery bank determines how much array you need to recharge it. In the case of your suggested 2000 Amp hour 48 Volt battery bank (massive) you would have about 12.5 kW of panel and three charge controllers. Such a system, btw, would supply about 24 kW hours of power per day - which is as much as a typical on-grid house.

    Yes understand what you are saying. My thoughts on battery are to to have a big enough battery bank such that we only hit 20 -30% DOD. That way we get a long life out of the batteries (all other things being equal with good maintenance and careful monitoring of the bank over the years). These batteries are BIG and HEAVY. About 5 tons i believe. I have to ship these in from somewhere in a container so rather get two sets now and save 10K on shipping costs if 2 sets will in fact be helpful to get more life out of the whole setup. Not much use to bring in one set now and find we need more and drop another 10K on shipping to bring another set in two years time. However everything gets super sized to accommodate 2 of these monster battery sets. I realize this but it is what it is - if we need this then we have to do it.
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Not Sure how to start off

    We have a thread that just has a lot of information, projects, and links (sorry--it is random at this time--More of a stream of consciousness in blog form).

    Basically, you should be working at (note--Links are for reference only--Don't know anything more about products or websites):
    Otherwise, you are probably going to look at commercial Watt*Hour (kWH) meters so you can measure AC loads and generator usage.

    If fuel costs are high and delivery is "spotty"--It is possible that using induction cookers/cook tops may be a possible alternative to Propane.

    Induction
    cooking - Wikipedia, the free encyclopedia

    Amazon induction cookers

    At home here, we also use thermos cookers--We boil the meat/etc. then throw it in a large thermos to cook in its own heat for 4+ hours--Possibly one more quick reboil and back in the thermos for another couple hours.

    Very popular in Asia and Asian markets (at least in the US).

    Amazon thermos type cookers

    Again--this may not make any sense for your needs/usage--Just throwing ideas out there.

    Once you have conserved and measured your load requirements, then we can talk about sizing your system... Note there can be a huge difference between refrigeration installations (age, maintenance, local temperatures, etc.). I doubt I can even guess at how much power those units you currently have will consume. Given you have a lake nearby--It is possible that you can setup a pump and heat exchanger--Or even use a de-superheater to heat hot water for the kitchen (solar hot water may be possible too--and that can be a good Do It Yourself type project using local materials and labor--Although solar hot water is still a big plumbing project with pumps and such--leaks and maintenance can be an issue) (see the projects thread at top of this post for lots of links).

    By the way, how much sun (by month or season) do you get--We typically use "hours of sun" (noon time equivalent) per day--You may get it in MJ per day or some other units.

    One alternative may be to run the place by genset (with instrumentation on your major loads/circuits) to find out how much power you need--Then design the system.

    There are alternatives too--One is to setup your system to run from battery bank/inverters at night/morning/during the day... And for late afternoon into evening, your generators recharge your battery bank and support other major loads (washing, cooking, lighting, entertainment, A/C, etc.). (A hybrid generator/battery system). You run the genset with constant/heavy loads (when it is fuel efficient). And batteries/inverters for light loads/quiet time. And you can add solar array later once you have everything sized.

    If you need lots of water--If you can pump during daylight hours/sunny days--Then a solar powered water pump will be very interesting... The pumps are not cheap (Grundfos SQFlex ~$2,000 +/- per pump, Lorentz pumps, etc.) but can run directly from a solar array--More efficient, no batteries/charge controllers, so the "power side" can cost 1/4 that of a full off grid battery based system.

    These type of pumps are also very efficient and "Off Grid Power" friendly (not a lot of surge current, every efficient pumping).

    If you need a lot of pumping--You can look at 3 phase pumps and VFD (Variable Frequency Drives)--The pumps are not near as expensive, and the VFD's are not too expensive either, but allow you to program pump speed for optimum pumping.

    Note that submerged pumps (or pumps with intakes below water level (pit beside tank, etc.), are much more efficient at pumping too...

    At the end of this, you will be ready for a side job involving conservation and planning for remote power systems.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off

    Hey Bill,

    I was hoping you would jump in here - i've been reading this forum off and on over the years and am always amazed at your calculations!!! I might add they make my head spin and ache ;-)

    Yes i get MOST of what you say but not all and i am not even going to try to follow your math and do my own calcs! The only subject i failed in school was maths !

    The gensets....... Yep understand very well all the issues with Gensets. Tricky to get a genset exactly the right size. Its ok if you have a static load that never changes. But in the real world, over time the load only ever gets bigger...or at least in my experience anyway. This is why i am specc'ing two gensets. One genset just cant do it all. At heavy loads the small genset cant cope and at light loads the larger genset is expensive to run and all the issues you mention of a large genset not run under load bite us on the backside! The only thing i can come up with is two gensets. Big plus to this is that when one goes down (and it will) we have a second one to keep is limping along till we sort the one that is down. I call that plan B. Out here it is well wise to have a plan B and C in place. OK so plan B is squared away, still have to think about plan C.

    Battery charger.......dreading this part of the discussion. At this stage (although still have LOTS of reading to do on this) i am looking at the SunnyBoy private AC grid system. Its a lot to take in and absorb though so still need to try to wrap my head around the concept. However if what i am reading and understanding is right it looks to me this is the way to go. I want to use the LARGEST panels i can get ( i am liking this panel http://www.solar-electric.com/kykd315wamus.html) so i think i need grid tie with battery backup? So i think the chargers are built in to the inverter?

    We get LOTS of sun. LOTS and LOTS. From April thru November there are few clouds in the sky - just bright vivid blue skies all day everyday. Rainy season is from November to April/May (depends if rain starts early or late and this varies year to year). There are days of overcast cloudy skies all days - and there are periods of blue skies during the rainy season. I need to get a meter to log the solar intensity. I think in the dry season we can bank (excuse the pun) on 8 hours of good strength sun per day. In the rainy season lets go with your estimates


    "Note, I am using lots of digits for the calculations so you can follow my math and avoid introducing more errors--" ...er , yeah right........ i think i'll just stick to your figures ;-)

    Agree it IS a BIG system. For sure no doubt at all. And costly. I'd prefer to just hook up to the grid and not do any of this but it aint going to happen, so......

    Problem is this is not a personal whim. We have a small commercial lodge to run with guests coming in and out all the time. Not huge numbers for sure but we intend to jack the place up and market the hell out of it to get the bed nights ratio way up. We intend to invest heavily to spruce the place up and raise the standard to a much higher level then it is now. That does not fit with " please dont turn on a light or plug in your laptop while you are here"........ "oh and by the way, its raw fish for dinner tonight as the truck with the gas broke down and will only be here well after you have left"...... hahaha i wonder what sort of review we would get on trip adviser if we operated like that :-)

    But at the same time i don't want to waste resources on a power system that is huge overkill. So many other areas are demanding our money on this project,......boats, scuba gear x 10, renovations, a home for our selves in this spot (don't want to take up a valuable money earning room while we live there). If i can do it for less i am all for it but my expectations are realistic - i figure on a large expenditure to set all this up. yes we are putting our life savings into this - we are not rich (and never will be owning a lodge in the bush in Africa - its all about lifestyle).

    I want/need a good quality system with the best electronics money can buy. Its along way to town to get parts to fix a broken/worn out this or that. Out here we say "cheap is expensive". I am not going to skimp on the inverter setup. We will do all we can to reduce loads (like LED lights throughout) but we have to have lights on all night around the property to keep guests feeling comfortable, we have pump water to keep the lawns and gardens green and nice looking, we have to do guests laundry everyday, we have to cook three meals a day plus coffee and cake/pastries/biscuits throughout the day for guests. We dont want to spend $6.00USD per gallon x 3 per hour 8 hours a day for the next 30 years. So what to do? The only thing i can come up with is panels, panels, panels, and a HUGE battery bank with all its cost and complexity. If this comes in below 120K USD i will be amazed.

    Agree that this is no job for an amateur. I DO understand the dangers of arching (the guy who is selling this place lost half of his foot from a big three phase system electrical shock - he is VERY lucky to be alive and he knows it). I just dont want to go to a professional designer and get led down the garden path.

    Warm Regards

    LM
  • stephendvstephendv ✭✭ Solar Expert Posts: 1,571 ✭✭
    Re: Not Sure how to start off

    Hi,

    Sounds like a very interesting project! Well it looks like you do have _some_ idea of the loads because you know more or less what appliances you're going to run and how many bungalows you're going to have. So even it it's just a rough number, you can still derive at least some number for the kWh you'll need on a summer day and a winter day (Add up each appliance power rating * the time they'll be on during the day, e.g. TV = 200W for 4 hours = 800Wh). This will help a LOT in sizing the battery bank correctly. If you get the size of the battery wrong, you'll need to run the generator more often or would have spent too much money on an unnecessarily large battery. But you can always correct this by buying another identical batt. 30% DoD might be too uneconomical. Industrial forklift batteries used in warehouses are typically discharged to 80% DoD every day, 5 days a week all year round. They then last about 5-10 years. You'll get a much better life out of them if you don't discharge that deeply, but with a solar powered system you will very rarely have to go to deep discharges. So letting them go down to 80% DoD a handful of time a year won't be too terrible in my opinion, and it lets you spend less on the battery.
    Not sure where you plan to source the hardware from, but you can get 3000Ah+ batteries in 2V cells. This will let you have the entire battery in a single string without the need to parallel. See: http://www.exide.com/dk/en/product-solutions/network-power/product/classic-solar.aspx and http://www.hoppecke.com/content/view/full/1210

    The generator is another item you don't want to get too wrong, and this will be based on the peak loads (e.g. TV = 200W + fridge = 100W + washing machine = 2kW = 2.3kW). There is also a limit of how fast you can charge a battery, usually 20A for every 100Ah of capacity. With 2 x 2000Ah 48v battery you'd only be able to push about 38kW into it. The generator will have to run the loads and charge the batts at the same time, so if the peak load was about 10kW then the max you'd need from the gen would be 48kW. It's good to keep a diesel gen loaded, so a 60kW diesel is about the right size (assuming my stab in the dark numbers for your peak load is right). If you have some spare land you could also considering growing a biodiesel crop like rapeseed, pressing it and making your own oil. It's fairly easy to convert a diesel genset to run on vegetable oil, or alternatively convert it into biodiesel with a bit more work. Might be a nice "eco" selling point for the lodge ;)

    You can run the system entirely on generator + batteries + inverter/chargers, so it doesn't matter if you undersize the solar panels at the outset. It's very easy to simply add more panels later on.

    If you plan on sourcing the material from abroad then this http://www.systems-sunlight.com/docs/12-02-12-18-16-23-SUNLIGHT-APS-SOLUTIONS-ENG.pdf might be of interesting. I believe they build a complete off-grid system inside a shipping container, then all you have do to is connect the panels on the outside and you're up and running. Don't have any more details other than seeing their brochure :blush:
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off

    Hey Bill - hi again,

    You ARE a prolific poster i must say! All you guys are a hidden gem on the Internet!! There is so much WISE useful information on this forum. The best resource i have ever found on all things power related. Kudos to Wind-Sun for providing this to us!

    OK have read through your last post and some useful suggestions there. I fully realize that trying to figure this out the way i am is nigh on impossible! I do like the idea of running everything on a genset/smaller battery/inverter and try to measure the power usage to gauge some idea. However this does not take into account the growth path we have planned. We only have 7 rooms and we want to increase that to 12. (Place is not making any money right now - in fact it never has as the owner has never lived there and has managers that run the place who i guess don't really care about the costs and the loss of running gensets all day and pumping water with gasoline all day). Right now they are mostly cooking on an outside fire (charcoal) with some gas range use, the fridges all run on GAS so i am going to get rid of those ASAP and buy NEW energy efficient fridges and freezers. ALL water is pumped by a 5HP Honda pump on gasoline and it runs a good deal of the day....etc etc. They only have a 5HP Honda Genset and i think about 6 solar panels connected to 8 or 10 12v 100 amp/Hr solar batteries. So they run the Honda genny a good deal of the day. No wonder it is not profitable!

    Regards water pumping...... this is much more intense then i have alluded to so far (just wanted to keep it simple for now). The other thing we will be doing here is collecting and exporting tropical fish for aquariums around the world. We are right now involved with suppliers in getting several container loads of glass to make aquariums out of. I wont go too far into this (unless you are interested) other then to say large volumes of fresh water from the lake flowing in to the tank, through the tank and back out in ONE PASS only then discard is the BEST way to keep the fish healthy. So in some respects we will have very high efficiency on pumped water - 95% of the water we pump will be pumped through the tanks first then out a drain of each tank to a reservoir in the ground. From there we will put a pressure pump on the reservoir and reticulate the water around the grounds/gardens/lawns. So we will use the pumped water twice.

    The aspect to this to understand is i will probably never stop adding tanks. I am planning 600 tanks for the first pass through on construction. About 800 - 1000 liters per tank x 600 = A LOT of water. I need to change about 25% per day. So i need at least 150,000 liters per day right there and this WILL grow. However this is not my first priority. The lodge is. I have to get that viable and producing income. So any excess power can be bled off to power up another pump to push more water through the tanks. At the same time i don't want to put in a system that has so much excess power that i am pushing 50 tank turnovers an hour through the tanks (although the fish would love this _ my wallet would not). So i do have to be reasonable and try to balance things out.

    My real concern is under provisioning rather then over provisioning because as i say i can suck up any excess power in water pumping alone. Plus if a 120K investment can let me run aircons in the rooms - hey what a bonus! Be nice to be able to say our rooms in the tropics by the lake shore has aircon in every room - but i doubt this will work out. Time to get both feet back on the ground!!

    I guess the bottom line is how much power do we need Vs how much can we generate from the sun Vs investment.


    Things to consider - a commercial lodge with guests coming and going all the time, fuel is expensive and a major undertaking to get supply (we often get fuel shortages in this far flung outpost so have to plan stock levels of Diesel because of that), Gas is EXPENSIVE HERE as there is NO local production - its all imported plus we can sometimes go 6 months with NO GAS in the country at ALL!!! This is a small African country where things you take for granted at home just don't work out here. We have to plan accordingly.

    Ahh the dilemma......i dont want to put in 300 panels if 200 will do the job. I sure as heck don't want to put in 50 panels to discover in my first month i need 200 more! As for batteries i really want to keep the DOD to 20% if possible 30% occasionally and 50% DOD in a spell of 4 or 5 wet days in a row. So to me that necessitates 2 x 2000 amp/hr @48v (although i would LOVE someone to talk me out of that - i would prefer to just run one string of batteries).

    Diesel at $6.00 per gallon pump price + transport to a remote area then load into a boat and cross the lake to get it into my store room is just not attractive!. The thought of 30 years of that is almost enough to put me off the whole thing!.

    LM.
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off

    Hi Stephen!

    I have been an avid follower of your site in the last year or two. I haven't been there in the last few months due to intense work load my side but i have read everything on your site about 10 times! Especially fascinated by your genset muffler system. Might steal your work on that.

    Yeah i hear you on what you have said and agree for the most part. Regards the battery bank - what i DO understand is the DOD Vs life of battery curves. I really would prefer 20 years on a set of batteries if possible. I can assure you battery care will be a daily task for my boys who are going up there to run the place. So we are prepped for that work load and understand battery care. I am not opposed to 50 or 60K's worth of panels to do the job if that's what is needed. I do get that you just don't get THAT much power from a a few panels. I would prefer to invest in panels then keep buying diesel over the years. Panels are at an all time low so great time to jump in at the deep end of panel purchasing. Diesel here only ever keeps going up - when you can get it.

    Was thinking of HUP SOLAR ONES. I've never read a review of anyone who has these so not sure if this is my best bet or not? I'm all ears regards battery bank to use.

    Think we will give the bio fuel a miss ;-) for now at least - we already have so many issues hitting us that i don't wont to deal with another aspect right now. But thanks for the suggestion. In time, when thins have settled down we may well look at this - just not right now.

    Every single item we need is imported. Everything except thatching grass! I would like to put batteries on the bottom of the container and panels on top of the batteries to fill the container up - most economical shipping is a FULL container. It costs about 10-12 K to get a container to the capital (from east cost USA - China half that but dont know about anything Chinese - can they be trusted? I believe in the Good Ol' US of A. I'm Australian and an American Ally so rather deal with my American friends but lets not get political lest i get banned here ;-))- the lodge is still another 1200 Klms past there straight up in the bush - place is remote! So getting ANYTHING here is expensive, so i have to consider that in my planning. 25K for batteries is not that much considering i have to spend half the cost of one set of batteries just to get them on site. So two sets now is not so bad in terms of cost IN MY PARTICULAR SITUATION - YMMV

    Thanks for the links and your thoughts - interesting!

    Warm Regards

    LM
  • Lake_ManLake_Man Solar Expert Posts: 27
    Re: Not Sure how to start off
    BB. wrote: »
    We have a thread that just has a lot of information, projects, and links (sorry--it is random at this time--More of a stream of consciousness in blog form).-Bill

    Bill - thanks for this - really really interesting reading in that lot! Thanks for the heads up!!

    LM
  • Eric LEric L ✭✭ Solar Expert Posts: 262 ✭✭
    Re: Not Sure how to start off
    So, using 4 hours of sun and your "10%" rated array (minimum expected good weather energy):

    15,325 Watt array * 0.52 overall system eff * 4 hours of sun = 31,872 WH = 3.19 kWH per day

    Minor point but in case it makes a difference, I'm sure BB meant to say 31.9 kWH/day.
    At the same time i don't want to put in a system that has so much excess power that i am pushing 50 tank turnovers an hour through the tanks (although the fish would love this _ my wallet would not). So i do have to be reasonable and try to balance things out.

    Given the lodge requirements and the high cost of moving things in there, I doubt this will happen. At the same time, depending on the head pressure on the pump, moving the required 6500 liters per hour might be doable as an add-on to the system down the road, given that that part of the pumping requirement would come straight from a lake (Lake Malawi, Lake Tanganyika, or Lake Victoria, I'm guessing).
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Not Sure how to start off

    Thank you Eric. Fixed.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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