New to solar.. Just inherited the system.. Advice please

BazzoBazzo Registered Users Posts: 6
Hi all, So I live in southern Spain, and have just bought a house that is off grid... The previous owner used it as a holiday and got by on the system he had put in.. (about 18 months ago)..
Originally the system was 6 x 240w panels, 4 x US185 XC 12v batteries all being looked after with Victron kit.. a 150/70 MPPT and a 5kw Victron Multiplus converter.
We had a few initial issues and had the original installers come and fit 3 more panels and 2 more batteries.. The sytem is multi voltage, but currently set up for 24v. We also have a 10kva backup generator, but fuel here is expensive, and I would rather improve the solar than spend on diesel.
The solar system is in the garage with a run of about 15m to the house. Everything we run is 240v AC

So my questions are this... the system is currently 24v, Would I be better off changing to 48v, and if so what do I need?.. and how do I reconfigure it...
The system is not perfect, we still run out and have to start the generator, so im guessing more panels and more batteries needed, Is this something I can buy and fit myself, or must I have the original installation company back to re-configure. The mppt and inverter are both multi voltage. but I guess I would need 2 more batteries to produce the 48v.. what about the panels?

Im starting to grasp how the system works, and how we need to alter our lives to live with solar... but we really want to have more capacity.

Many thank for your help in advance..
Bazzo

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    I think first you need to live on the current system for a while.

    Living on solar for the first time, you are not likely to understand how things work. You will learn to conserve and to try to run loads when you have excess solar energy. Things like doing laundry on sunny afternoons and cooking on sunny days if you cook with electric. Likely you have yet to give up on some 'grid connected' conventions. Blow dryers in the morning? lots of hot stuff in the morning? Coffee, toast, eggs all off solar?

    You will end up with a massive system if you don't adapt to life off grid.

    "Everything you run is 240V AC" so does that include a oven? A/C? water heating? Some things might be better done with gas, some might be done with different equipment...

    There are reasons to change to 48 volt, but I doubt your inverter is really multi voltage? I went and looked at the "Victron Multiplus converter." and it does look to be voltage specific, so it would have to be changed to move to a 48 volt system. If you decide to add any more panels to your array this would be a consideration, you could double your array with out adding a charge controller if you moved to a 48 volt system. If you stay with a 24 volt system you would have to add another charge controller, you appear to be at the max of you charge controller for a 24 volt system.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BazzoBazzo Registered Users Posts: 6
    Yes we are learning to live with solar, and we are getting it... But....We have a pool pump to run, yes the oven is electric.. but that's going to gas, all heating and water is gas, and we have no A/c

    Im confused though.. the Multiplus is indeed 24v/5kw .. if at max 5kw
    then 5000/24 =208A yet the Mppt is limited to 70A

    Also the Mppt is limited to 2kw max Pv and although I have a theoretical max of 2.25kw, most ive seen has been 1.7kw... Yet the installation company is telling me I need more panels and more batteries????

    So what do I need to do to stop having to run the generator... more panels/batteries .. if so whats the max for my current set up... I know you are gonna say live with it... But we have been in the house 9 weeks now, we work our day around the solar... not much on first thing, pool pump about 10, washing/ironing during day when sunny, and never done at same time..
    All bulbs in house are energy efficient.. as are most appliances.. yet we still run out... System is only 18months old and installers tested the batteries when they added the 2 new ones...

    Also.. why are the panels added in 3's?

  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    You are new to this!

    Think of this as 2 systems;

    1; A charge controller that is 150/70 MPPT, that translates to 150 volt maximum input and 70 amps maximum output that charges the battery bank, it can take any input upto 150 volts and down converts the wattage to a point that is proper to charge the battery. You are setup to have strings of 3 panels 240watts X 3 = 720 watts, likely around 90 volts and 8 amps. In series the voltage adds and the current/amperage remains the same. amps x volts = watts so 8 amps at 90 volts = 720 watts. The problem is the panels must be rated at a standard amount of light, typically they rarely reach this standard. Panels typically put out 70-75% of their panel rating so a 240 watt panel is likely to put out 180 watts. So you currently have 3 strings that are rated combined at 2160 watts but likely put out @1620 on most sunny days (cold days you might come closer to the panel rating.

    2; an inverter that draws energy from the battery bank and converts it to AC 24v/5kw 24 volts outputting up to 5 Kws

    Just so you understand, this is a very large inverter. if run at "5000v/24 =208A" it will try to draw current/amperage at 1/3rd of your batteries capacity. Batteries are rated at a constant draw of 1/20th of their capacity, if they current is draw off faster than this, the effective capacity will be less. Also you will experience voltage drop that may trigger a low voltage disconnect. If your running the oven and the pump kicks on your inverter might shut down due to appeared low voltage coming into the inverter. Your battery might be fine. Heavy wiring will help, but drawing above 1/5th of capacity is going to drop the incoming voltage.

    I will say to use what you have for a while, you might measure where you're using electric. Can the pool pump be turned off at night? perhaps turned on and off every other hour? I suspect it is a very large energy draw and you may have pinpointed the major issue. I know some pools have moved non chemical means of purifying water, I don't know how this would effect the pool pump. There may be more energy efficient pumps also cleaning the filter more often will help the motor run easier. So how much energy does you pump use?

    I run a 24 volt system and try to do too much with it, I have a 4kw array, near 2x your size and a 800ah 24 volt battery. You appear to have a 600 Ah battery bank (voltage adds and amperage remains the same in strings) I, personally would not have added batteries to an 18 month old battery bank.

    Bill should be along shortly and ask that you get a handle on your loads, It would be a good idea to know where your energy is going, I understand there is a energy monitor like the 'Kill-A-Watt' meter we have in the US. plug the meter into the outlet and the load into the meter and you can find out momentarily and over a period how much energy things use. Items that are hard wired like your pool pump, could be determined by a clamp meter.

    Have you added anything major? The solar setup was designed for weekend use so the batteries had the week to recharge, so you could expect some additions.

    I say use what you have, since if you add to the system you will likely want to go to 48 volts. You could do this by adding 2 batteries and switching out your inverter/converter but that won't be cheap and the batteries will be suspect and likely you will need to change them all out about the same time as the original 4 (another 3-4 years). I should have gone to a 48 volt system but I had just purchased the forklift battery 2 years prior, It may last 20 years so I didn't switch... So I feel your pain. I actually intend to add (actually put up, I've had them for a couple years now) 2500watts to my array to run opportunity loads during the day. More A/C and water heater. I will also get more charging on overcast days. To do this I'll have to have the charge controller limit their output so I don't charge at a 20% rate...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Please tell us how those batteries are configured. I am assuming they are 2 in series for 24V and 2 sets in parallel, right? I found these listed at 200 Ah and 220 AH, so they will produce 400Ah or 440 Ah. Do you know what their Ah rating is?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    Opinions vary but a broad rule of thumb:
    Under 1000 watts - 12 volt is good
    1000 - 2000 watts - 24 volt is good
    Over 2000 watts --- 48 volt is good

    Changing to 48 volts is looking for more complications than I would seek if I were you. Maybe you could run the pool pump less? Smaller, more efficient pump?
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BazzoBazzo Registered Users Posts: 6
    Thanks for all your time and input.. Much more than I expected.. What a nice bunch you are !!!

    Yep.. I am new this this LOL....
    The pool pump is 1.25kw, and only runs for an hour around 11am...
    Not added anything major...extra small fridge for the beers!!.. plasma tv (will change to led as soon as possible as I know plasma is power hungry.

    I was aware about the adding battery issues.. But could not afford to replace the existing 4, with maybe 8 new ones.. they cost 400euro each here!! They have a 7 year warranty and were installed by the same contractor that fitted the system, so if there are any issues they will have to cover the warranty... What issues may I face? and would I be better off adding 2 more sooner rather than later? will that need more panels to charge them all??? The batteries are all matched at 172ah... must any new ones be exactly the same make/spec?

    I realise now that I will have to stay with 24v system as replacing with 48v would be too expensive,.. But what can I do to improve the situation, that is the question...We want to live as normal life as possible and would rather spend on panels and batteries than diesel for the generator... Interestingly the contractor suggested more panels and batteries, but at what point would I be wasting my money.. i.e no more gain?

    Batteries are configured 2 in series, to give 24v then 3 x parallel...

    Thanks for all your advice!!
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    The electric oven can not be used without running the genset. Same with the pool pump.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    That's a hefty price for batteries!

    The added fridge, even a small one will likely use near 1 Kwh a day! Small ones use just a little less than smaller full size fridges! also be aware of where the fridge lives, if it's in warmer areas it will use more, out by the pool? In the sun? will increase the energy use. Even in the home out of the sun/heat this is a substantial load. I understand inverter type fridges are available in Europe and they use a good bit less energy.

    Adding more panel becomes expensive at this point, more panels will require another charge controller. Charge controllers work based on out put current, since current is reduced by half between 24 and 48 volt systems, I think it is important to get a handle on whether you will need to move to a 48 volt system. In a 48 volt system you could double the size of your array without needing another charge controller.

    I'm not familiar with Victron system, but you might check your settings, typically you would equalize flooded lead acid batteries before adding to the battery bank. 3 strings is more than I would like to have already and my first reason for saying try to live within the energy you're producing.

    Do you have a battery monitor? How do you know you need to run the generator? A 2000 watt array even in sunny Spain would require pretty good conservation. Your pool pump is using an hour of your charging, though it needs to run during the prime charging hours. A second fridge generally would not be in order. I suspect since you have moved from a grid connected home, little things have yet to become routine, lights always off when you leave a room,...

    I think Plasma TVs needs to be on a on off switch behind the plug, I think they use more enrgy in stand by mode, though this might be old information. Also if you have a satellite receiver some use as much energy off as they do on! You want one the stores it's settings so you can turn off the electric to the receiver (as switch or power strip).

    You might look into finding a meter to measure what your loads consume We have a Kill-A-Watt meter here in the states. They have a cheapy China meter available on Ebay. It might work might check into a similar meter for your power outlet/voltage. Maybe check with the power company you aren't using...lol.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    Forgot, yes batteries added should be the same size/capacity even make, though I would not recommend adding any more strings.

    Thinking into the future is part of what solar is all about, if you need to switch/add capacity often it's best to do this at the same time. I suspect they have 6 volt batteries in similar size cases with near double the capacity. If you stay with 24 volt system you might switch to 2 or even 3 strings of these. You could also look into a fork lift/traction type battery. They have slightly different characteristics but tend to last a good bit longer and may offer a better value.

    Remember if you need to replace the inverter/ charger that the old one will still have a good deal of value and you won't have to replace your charge controller so it might be a near even nil difference, though you would have to invest in the new before selling the old. Your installation company might even help you with this since they know the history of the inverter, they might offer a 'deal' to a new user... Victron might even warranty by year of build so they could offer the remainder of the warranty, I believe they have a 5 year warranty.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    Ironing....ouch. Big energy user. Did you say your tv is plasma? New LED tvs run on energy conservation mode will help a lot. Also....a smaller genset. Yours is a monster.

    If you don't have an energy conservation mode.....just darken the screen. It is significantly screen brightness that consumes energy.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BazzoBazzo Registered Users Posts: 6
    Confused///

    cannot use oven or pool pump without genset... really .. Why?.. solar typically pulls in 1.7kw during day, (my panels face due south and mounted on 30deg roof) and pump is only 1.25kw.. Already realise that electric oven is a no no as it will probably pull more than the pv can supply, and deplete batteries.. Although it does work... on PV only That aside, gas oven is ordered

    Don't add more strings of batteries you say... Why is that? My understanding is that more batteries = more storage, although more panels will be needed to charge adequately?.. and more panels will make more useable Kw available during the day, ie to run pool pump and extra fridge etc...

    I don't expect to go days without sun and not have to use genset... but as we have 300 days of sun here every year I would have thought that my victron multiplus 5kw.24v and Mppt 150/70 should be adequate if paired with the right amount of panels and storage... which in my thought train, its not... But then I really do know nothing about the tech side of this

    Its difficult coming from a grid house all my life, and I know we have to make changes if we want to live off grid (no choice!).. all non essential appliances are unplugged when not in use, and sat receiver is always off when not in use.. not standby, and we have always turned lights etc off when not in use..

    It seems you guys are saying that my current setup cannot be improved any, or it has reached its capacity... So I guess the installers are just trying to sell me kit that will not help any? the installer is running a 48v system and 12 batteries!!! What is the downside of having more batteries?.. as I understand it the more Ah I have, the longer I can go without sun?

    Im desperate to keep the system I have, but make the absolute most out of it... Before joining this forum I was on the verge of adding another 3 panels and 2 more batteries making 8, 4 at 18month old and 4 new,....... now I have doubts... can someone explain in simple terms why 3 more pv and 2 batteries will not improve my situation?
  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    I did NOT say not to run your pool pump or oven, You are welcome to, and you are running the pool pump at pretty much the ideal time, I suspect with moderate loads while the pump is running that you will typically draw down your battery a bit during the hour it runs, that's fine, it's just an early hour during the major charging time. Tonight I both cooked a pizza(1200 watts) and heated water(900watts) after prime afternoon hours and likely pulled a Kwh from my battery bank before my normal evening loads, I knew I would get a little help from the afternoon and setting sun.

    I say don't add batteries for the same reason that the installer is running a 48 volt system with 12 batteries! When you run more strings of batteries it becomes harder to keep the batteries in balance. Your new and we haven't talked about the batteries health and what you are doing to maintain it, but flooded batteries, in my opinion should have a maintenance equalizing every month, and you should check the specific gravity of each cell each month until you have a good feel for your system some people do this every month for the life of the system, it's not a bad idea. If your having problems, which you are, you should be checking to see that your batteries are all reaching full capacity together and that some are not too low as other reach capacity. The more strings you have the harder it is to maintain the batteries balance and this only becomes harder as the batteries age.

    Note that your installer has a 48 volt system so they only have 3 strings, above 3 strings you are likely to have more problems. A good installer should be willing to discuss this with you.

    I have no problem with you adding batteries and solar panels to your system, but I would much rather see you have a 48 volt system with a single charge controller and inverter and a 4000 watt array and 3 strings of 4 batteries, than a 24 volt system with a 4000 watt array 2 charge controllers and 6 strings of 2 batteries. The 48 volt system would be more trouble free, and be easier to track down any problems.

    I have suggested you get a good handle on your loads, but I can 'see' you run close to using what you have coming in now. You have 3 major loads every day in the pump and 2 fridges, That is likely 3kwh's on their own. If you want to just add batteries and panels, you may well get the system to work for a while, but you will have more problems down the road and more maintenance now. It might be good for you to use one of the on line system sizers, you plug in your loads and it tells you what size system you would need.
    BRAZZO wrote:
    ...can someone explain in simple terms why 3 more pv and 2 batteries will not improve my situation?

    Because your Charge Controller is at maximum capacity now! To add more panels you will need to add another charge controller! I did my best to explain this in a prior post. This is one of the reasons to see if you can stay at 3 strings and work with a 24 volt system. With a 48 volt system you could have a 4000 watt array one charge controller. There is a market for your inverter/converter. If you need a larger system I strongly suggest you change to a 48 volt system now! Your smaller batteries may last 5 more years and you can add 2 more and reconfigure your batteries for a 48 volt system.

    I actually am, in much the same situation you are! I live on 24 volt system and have 2 charge controllers with higher capacity than you have and I will add a third to increase my array. If I didn't expect 15 year life span from my battery I would seriously look into a 48 volt system. Unlike you I would have to sell my battery, there is a very small market for a used 1100lbs (500kilo) battery and then you have to transport it.

    For me it will be a wait of another 10 years to expand my system to 48 volts. I'm actually trying to live with the inverters I have now rather than pump money into a system that should be a 48 volt system. I had just purchased the battery when I was forced to move from the cabin I had built on my own land. Changing home owner covenants. My new place is not as well designed for solar.

    I hope I have helped, if you could provide the ways in which you are measuring the battery capacity and what is triggering your need to run the generator, I and others might be able to add some insight. You may have other problems that we can't see. Do your batteries tend to be at 100% capacity at the end of the day when the sun is shining? Over night on these days do you use all of your stored energy?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    I hope I haven't been too harsh, I seriously looked at switching to a 48 volt system. I too would save 1 charge controller, and I have not purchased a premium larger inverter to run my home, rather staying with a smaller one, so far, I have to watch what loads I put on my inverter. I often, like tonight turn on one load as soon as another has finished. Turning on a 900 watt water heater as soon as the 1200 watt pizza oven turned off... I'm pretty stubborn and might make it 10 years, if I do I might well be as cheap as the power company, largely because I use so much of the energy that comes in. I wish you the best, I don't run a generator, and someone said you had a large one, but I didn't see that posted. There are good and bad generator setups and you might ask questions of the generator crowd here on how, to run yours most effectively.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    softdown wrote: »
    Ironing....ouch. Big energy user. Did you say your tv is plasma? New LED tvs run on energy conservation mode will help a lot. Also....a smaller genset. Yours is a monster.

    If you don't have an energy conservation mode.....just darken the screen. It is significantly screen brightness that consumes energy.
    Note that there is a difference between LDC displays using LEDs as backlight (not too bad, great compared to plasma, and in some cases they may be able to selectively dim the backlighting in parts of the screen) and OLED screens where the source of light is pixel sized LEDs and the intensity of each pixel is modulated. No waste of backlight power behind dark areas of the screen. The latter is the coming thing for cell phone displays to maximize battery life.
    SMA SB 3000, old BP panels.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    With less than 3 Kw of solar capacity, one tends to be camping as much as living comfortably. I would recommend reading a book or two on solar power.

    Bigger inverters use more power than smaller ones. Your 5 Kw inverter is quite large. Bigger gensets use a lot more fuel. The old pros here like to run gensets around 1000-2000 watts in size when they can. Especially considering Spanish fuel prices.

    Running refridgerators off of solar is generally to be avoided. Though there are models that are very energy efficient however. Readily available in 12 volt or 24 volt. Your inverter may have a 12 volt accessory on it.

    How many people in the household? If more than two, you probably should figure on switching to a 48 volt system.

    As for me answering questions while asking them? I have run a 12 system for years and read four solar books. Needed help getting my new 48 volt system operational. Should happen tomorrow with luck. So I am both new and old.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Bazzo wrote: »
    Confused///

    .........

    Im desperate to keep the system I have, but make the absolute most out of it... Before joining this forum I was on the verge of adding another 3 panels and 2 more batteries making 8, 4 at 18month old and 4 new,....... now I have doubts... can someone explain in simple terms why 3 more pv and 2 batteries will not improve my situation?

    I can see where you are coming from, and I can hear your frustration... but as I wrote earlier you need to document your usage across the day and night so that we can all review it and look for opportunities to possibly improve your system or, as is, get it to provide what you need powered. All good systems start with a complete plan, I listed every light and item plugged in, by room, and the amount of time, in minutes, and time of day it was used for my system... For us it payed off in the house design/construction too...

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BazzoBazzo Registered Users Posts: 6
    Hi , It was Softdown that said I cannot run pump or oven without genset..

    Yes the genset is 10kva/8kw, although I believe it has been "turned down" and will run all night on about 10euros... as I needed it too when we ran out of power at 11pm one night, it had been particularly cloudy all day, and we had guests that evening so used the oven. Today however we have had the pool cleaned, so pump was running extra time, wife has used oven, yet I still expect to go through the night without issue.

    The batteries are definitely 12v 200ah and I believe that the Victron charge controller looks after the batteries pretty much automatically, except for checking levels and gravity, which I will do every month. I may be wrong, but the installer said all I needed to do was check levels.
    I understand that the charge controller is 2kw max.. and technically im over that at 2.25kw... however the most the panels are expected to produce is about 1.7kw (don't understand why)..

    Am I right in assuming that the charge controller is only capable of passing 2kw to the batteries.. anything over that is either wasted, or used as it is produced?... My thinking is that if I add more panels to supply more watts during the day, then the batteries should go into the night fully charged as I wont be pulling them down during day... OR are you saying that I can only connect a max 2kw to the charge controller FULL STOP?.. hence the need to install a 2nd charge controller...

    I take on board all you have said about changing to 48v and I agree that would be better in the long run, but right now I cant afford it along with expanding the system.. hence why i was edging towards 3 more panels and 2 more batteries. .. my thinking is that if I have to change in a year or 2, I will still have the panels and batteries.. whereas if I change my inverter now to 48v, I would have to add batteries, and still only have 9 panels.

    The charge controller has a digital display with battery monitor.. plus a host of other info available, That's how I can see state of battery, seems to be a clever bit of kit... But how do I know to run genset.. well either inverter goes to low batt state... or if I know I have to pull power above and beyond I go and start it.. Today I was working on the house, pool running, and I had to do some welding on gates, so I figured it would make sense to run gen while I was working....I am looking for a way to make it auto start (it has an ignition key and inverter is capable) although I will not be able to auto stop it as that is done manually and I cant be messing with solenoids etc.

    I guess the most important question here for me is the one in para 3... the 2kw spec on the charge controller... if I have more kw available is it either used or wasted... of can I not run more than 2kw???

    Im having a meeting with the installation company next week, to see if there is a deal to be done to go to 48v, but I seriously doubt it. .. so stuck with 24v..... but then if I have to buy another charge controller then im stuck.. I guess it will have to be 48v... and something will have to be sold to cover the cost.


  • BazzoBazzo Registered Users Posts: 6
    My reasoning behind the more panel/batteries. route... I have 2.25kw theoretical PVw... in reality only 75% of that.. I,e 1.68kw so the Mppt still has a little to give...
    If I add 3 more 240w panels, giving me a total theoretical of 3kw.. in reality 75% of that ...2.25kw .. so slightly over the rated 2kw for the Mppt... im guessing the excess 250w would be ignored?
    Apologies for my ignorance.. but I was thinking more panels would sort my daytime consumption... even if the charge controller didn't use all the available kw.... and 2 more batteries would give us the small cushion we need... After all, its not that the system isn't coping MOST of the time... it just needs that little extra help occasionally... maybe once a week...

    Or do I leave the solar part of the system as it is, and investigate an autostart option for the gen.,... A whole other topic I guess... But I cant help but think that the existing system is so close to coping with the demands, maybe panels/batteries AND an autostart for gen is the answer... My concern is that I don't want to be hitting the low batt threshold as I imagine that will not do the batteries any good.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    When to start the genny? well you have to know what loads you are going to have and decide BEFORE the LVD kicks the inverter OFF , why? because at that time you will have to feed the heavy loads as well as charge the batteries. the lower you have drawn the batteries the longer you have to run the genny. There is a concept called 'opportunity loads' and this is when you know the batteries are fully (>90+%) charged also identified as when the charger gets the battery into FLOAT stage, after an ABSORB period , as set in the charger.
    The concept used is to use the right sized genny to take you through the BULK phase and then let the PV go through the ABSORB and into FLOAT. So you have full batteries, then you start using some of the, about to be lost, power coming in from your PV... that is run loads that otherwise would deplete your battery storage that you need for overnight...
    Bulk is a stage where the charger sends as many AMPS into the battery as it will take and VOLTAGE RISES slowly, to the ABSORB VOLTAGE, then the charger enters ABSORB and the AMPS slowly fall to the FLOAT value and the when the ABSORB criteria of Volts and Time are met, enters FLOAT stage... again for a set time.. the above is for a sunny day, if you don't get sun you run the gen a bit longer, and based on your expected LOADS you guesstimate if you can "make it through the night"...


    this is a must read for you... http://forum.solar-electric.com/foru...erator-support
    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • PhotowhitPhotowhit Solar Expert Posts: 5,653 ✭✭✭✭✭
    You can add more panels to your array, and it will help you reach the 70 amps output level, 70 amps at 24 volts = 1680 watts so that is the max output at 24 volts, you should reach 28 volts during the charging cycle, and at 28 volts 70 amps = 1960 watts at the point the battery/system reaches 28.4 or so your battery bank will slowly accept less current. extra array/panels will help on cloudy days and it will help during the morning and evening hours, but since the charge controller can only put out 70 amps it won't help charge the battery when you are running loads during the day. To do that you would need to add another charge controller.

    I, personally, would rather turn off a fridge and put my beer in the wife's fried and even go so far as having to ask her permission!, rather than run a system with 4 strings of batteries. people do, do it. I would not feel comfortable doing it.

    Your inverter/converter has a 5 year warranty, I would think someone would love to buy it at a 75% of a new one, that would be about what an additional charge controller would cost.

    It seems to me that you don't charge your batteries when you run the generator?

    I don't know Victron's system, but a reading at the charge controller might well not give you a good idea for the battery capacity. Loads can effect the voltage and that and the current passing through the charge controller is all the charge controller can 'see'. I believe Victron makes a shunt based battery monitor, that is what you need if you want to know the capacity of your battery bank. Ask your installer if you have a "shunt based battery monitor" it may use the charge controllers display but you want a monitor that measures the current going into and out of the battery, NOT the charge controllers shunt!

    Softdown is not yet familiar with larger systems, he will learn. Every body contributes from their knowledge base, he has run smaller systems and in smaller systems, I would agree. Today I would recommend solar and batteries over propane for refrigeration in areas with year round sun. Most of the people here have started with smaller systems and grown into their larger systems. You have just been dropped into living with the limits of solar.

    Having said that, other things can give your inverter the idea that the battery bank is low. My guess is that it can only 'see; the voltage that is available. if you tried to run your oven at night, without the help of the energy coming in from your solar array, it might well see low voltage from the excessive energy draw from your batteries. Your batteries rated at 178 or 200 amps just store energy. their rating is based on an energy use/draw of 1/20th of their capacity. So if you had a 400 amp hour 24 volt battery bank and ran your oven at night, your oven is likely 3500-4000 watts 3500 ÷ 24 = 145 amps or 1/3rd of your battery capacity or 1/4 with a 600 amp battery bank. at these larger use/draws your battery bank is effectively smaller! This may or may not be 'your' battery but Here is information about US 185 XC2 . I think this is likely your battery as you gave me 178 amps as their capacity and that is the 10 hour rate. and 200 amps their 20 hour rate. Another thing happens when you put a large load on your battery bank, the voltage drops and the voltage that is 'seen' by things like your charge controller drops even more due to wire losses. a wire that has almost no voltage drop handling 50 amps might have 4-5% loss with a 150 amp load. This can have you inverter charger shut down to protect your battery bank even though the battery bank is mostly full. Even large burners on electric ovens can pull 2500 watts!

    I know it's all a bit overwhelming, just think in a couple years you will be helping out others as they struggle with their systems!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    We are approaching several prime solar months. You will probably be fine for several months now. Almost everybody bleeds during the winter time.

    Edit:...pffft, like S Spain has a winter. Still...longer days help of course.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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