New Stand Alone PV System using Victron and Rolls
bernithebiker
Registered Users Posts: 15 ✭
Hi - been reading through some posts here, and learnt a fair bit.
I've designed a small system for our flat in Majorca, Spain, as we cannot get grid electricity for the time being (6 months at least).
So we need a PV system to tide us over.
We are limited on roof space so I have to design around 2 x 280W panels for now, hopefully being able to add 2 more later.
I have specced a Victron Phoenix 3000W inverter, and 4 x 6v Rolls S 605 (485Ah each) batteries.
Charge controller is a Victron BlueSolar MPPT 100/50.
All heating is done by gas, so no worries there.
Otherwise we have LED's everywhere, don't really cook at home (holiday flat), and can do washing at a laundrette if need be.
But being English, we do like a cup of tea, as the kettle will be boiled a few times a day.
Does this system seem 'functional' and any opinions on the equipment chosen?
Cost is about 3500 Euros or 3000 US.
Thanks!
I've designed a small system for our flat in Majorca, Spain, as we cannot get grid electricity for the time being (6 months at least).
So we need a PV system to tide us over.
We are limited on roof space so I have to design around 2 x 280W panels for now, hopefully being able to add 2 more later.
I have specced a Victron Phoenix 3000W inverter, and 4 x 6v Rolls S 605 (485Ah each) batteries.
Charge controller is a Victron BlueSolar MPPT 100/50.
All heating is done by gas, so no worries there.
Otherwise we have LED's everywhere, don't really cook at home (holiday flat), and can do washing at a laundrette if need be.
But being English, we do like a cup of tea, as the kettle will be boiled a few times a day.
Does this system seem 'functional' and any opinions on the equipment chosen?
Cost is about 3500 Euros or 3000 US.
Thanks!
Comments
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bernithebiker wrote: »Hi - been reading through some posts here, and learnt a fair bit.
I've designed a small system for our flat in Majorca, Spain, as we cannot get grid electricity for the time being (6 months at least).
So we need a PV system to tide us over.
We are limited on roof space so I have to design around 2 x 280W panels for now, hopefully being able to add 2 more later.
I have specced a Victron Phoenix 3000W inverter, and 4 x 6v Rolls S 605 (485Ah each) batteries.
Charge controller is a Victron BlueSolar MPPT 100/50.
All heating is done by gas, so no worries there.
Otherwise we have LED's everywhere, don't really cook at home (holiday flat), and can do washing at a laundrette if need be.
But being English, we do like a cup of tea, as the kettle will be boiled a few times a day.
Does this system seem 'functional' and any opinions on the equipment chosen?
Cost is about 3500 Euros or 3000 US.
Thanks!
No plans to ever cook there? Since you have gas, it would seem a natural to have some sort of gas appliance to heat water for tea. Resistive heat takes a lot of power, but if you get something to measure the kettle like a kill-o-watt meter you should be able to predict how much you need.
Also, did you know that larger inverters take more DC to product the same amount of AC? 3000w sounds large from what you describe. What does a kettle use, 750w?
As for heating, does it use electric fans to circulate the air? You will need to spec that out as well.
I suppose that if I could walk a few minutes to get tapas, I might not cook much either
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bernithebiker wrote: »I've designed a small system for our flat in Majorca, Spain, as we cannot get grid electricity for the time being (6 months at least).
So we need a PV system to tide us over.
The "right answer" is to not spend much money (if any) on solar power... It really only makes sense in the long term (years). Of course, the grid may never come, be too expensive, or after living off grid for 6 months, you may decide you don't want the grid.
However, if you have a small solar system to power LED lighting and perhaps a computer/tv for a few hours per night--The system could be small enough/cheap enough that you may keep it for emergency power outages or even be able to sell it to the next person needing small amounts of power.We are limited on roof space so I have to design around 2 x 280W panels for now, hopefully being able to add 2 more later.
I have specced a Victron Phoenix 3000W inverter, and 4 x 6v Rolls S 605 (485Ah each) batteries.
Charge controller is a Victron BlueSolar MPPT 100/50.
I am all about building a "balanced" system. The loads/power needs drive the battery bank. The battery bank drives the solar array sizing... And of course, the loads also drive the solar array sizing. You want to keep the battery bank "happy" -- Or else it will not be long for this world.
Since you have a battery bank chosen--We will make the system design off of that (since we really do not have loads at this point). First, what could such a battery bank supply? Assuming 2 days of storage, 50% maximum discharge (longer battery life) and using AC power:- 485 AH * 24 volt battery bank * 0.85 inverter eff * 1/2 days storage * 0.05 maximum discharge = 2,474 Watt*Hours per day
Next, how much power can you get from such a bank:- 485 AH * 24 volts * 0.85 inverter eff * 1/20 hour discharge rate = 495 Watts -- Or roughly 495 Watts for 5 hours per night for two nights (no sun)
- 485 AH * 24 volts * 0.85 inverter eff * 1/8 hour discharge rate = 1,237 Watts maximum continuous draw from battery bank (dead in less than 8 hours)
- 485 AH * 24 volts * 0.85 inverter eff * 1/5 hour discharge rate = 1,979 Watts maximum short term draw (minutes to an hour or so)
Also, larger inverters "waste" more power with small loads... A small inverter may draw 6-10 Watts just "turned on"... A large inverter may draw 20-40 Watts or more just "turned on"... That can be a significant amount of load for a small system (if you leave the inverter turned on 24 hours per day to charge cell phone, run lights, etc.):- 30 Watts * 24 hours = 720 WH per day just with a large inverter on 24 hours per day and no loads (almost 1/3 of your daily load budget in this example)
- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 913 Watt array minimum
- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 1,827 Watt array nominal
- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 2,375 Watt array "cost effective" maximum
http://solarelectricityhandbook.com/solar-irradiance.html
Palma
Average Solar Insolation figures
Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
(For best year-round performance)
Jan
Feb
Mar
Apr
May
Jun
4.19
4.84
5.90
6.37
6.35
6.62
Jul
Aug
Sep
Oct
Nov
Dec
6.82
6.66
6.00
5.27
4.06
3.87
It looks like 4.0 hours of sun minimum per day will cover most of the year:- 2,474 Watt*Hours per day * 1/0.52 end to end system eff * 1/4.0 hours of sun per day average = 1,189 Watt solar array minimum (to meet load guesstimate)
All heating is done by gas, so no worries there.Otherwise we have LED's everywhere, don't really cook at home (holiday flat), and can do washing at a laundrette if need be.
The above system (with the larger solar array) would pretty much run your home very nicely. And with conservation, you might find a small electric refrigerator that could even live on that system too.But being English, we do like a cup of tea, as the kettle will be boiled a few times a day.
Everybody has their "needs"... With the size system you are looking at, an 800-1,200 Watt kettle would not be a big problem.
Your thoughts?
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Wow, firstly thanks for the comprehensive replies, which I will now look into!!
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No plans to ever cook there? Since you have gas, it would seem a natural to have some sort of gas appliance to heat water for tea. Resistive heat takes a lot of power, but if you get something to measure the kettle like a kill-o-watt meter you should be able to predict how much you need.
Also, did you know that larger inverters take more DC to product the same amount of AC? 3000w sounds large from what you describe. What does a kettle use, 750w?
As for heating, does it use electric fans to circulate the air? You will need to spec that out as well.
I suppose that if I could walk a few minutes to get tapas, I might not cook much either
You're right, a gas hob would make sense, but the kitchen is new (we have only had the flat 1 year) and it has a shiny new induction hob.
The reason for a large inverter was future proofing, and being able to run say, kettle and toaster at the same time with no issues. Kettles over here (UK/Europe) tend to be at least 1500W, mostly 2000, often 2500.
The heating is by piped radiators, so no fans, just the circulation pump, about 40W I believe.
And yes, you're right, as we are right in the heart of Palma, a huge choice of restuarants is on the doorstep! -
The "right answer" is to not spend much money (if any) on solar power... It really only makes sense in the long term (years). Of course, the grid may never come, be too expensive, or after living off grid for 6 months, you may decide you don't want the grid.
There are 2 ways to approach this; my first was a pure 'emergency' system. I found a product called Minijoule that has a 200W panel and a self contained unit on wheels that contains a 100Ah battery and a 1500W inverter. It is 1400 Euros. This would just allow some lighting, and the fridge (yes there is a small one).
But then, for not SO much more (3400), we could have a system that would keep the flat 'useable' and maybe even stay off the grid ad infinitum which would be nice, although we would need to upgrade more it seems. Also, if it doesn't work out and we end up getting back on the grid, both systems should be quite saleable, 2nd hand.
However, if you have a small solar system to power LED lighting and perhaps a computer/tv for a few hours per night--The system could be small enough/cheap enough that you may keep it for emergency power outages or even be able to sell it to the next person needing small amounts of power.
I am all about building a "balanced" system. The loads/power needs drive the battery bank. The battery bank drives the solar array sizing... And of course, the loads also drive the solar array sizing. You want to keep the battery bank "happy" -- Or else it will not be long for this world.
Since you have a battery bank chosen--We will make the system design off of that (since we really do not have loads at this point). First, what could such a battery bank supply? Assuming 2 days of storage, 50% maximum discharge (longer battery life) and using AC power:- 485 AH * 24 volt battery bank * 0.85 inverter eff * 1/2 days storage * 0.05 maximum discharge = 2,474 Watt*Hours per day
There is a fridge.
Next, how much power can you get from such a bank:- 485 AH * 24 volts * 0.85 inverter eff * 1/20 hour discharge rate = 495 Watts -- Or roughly 495 Watts for 5 hours per night for two nights (no sun)
- 485 AH * 24 volts * 0.85 inverter eff * 1/8 hour discharge rate = 1,237 Watts maximum continuous draw from battery bank (dead in less than 8 hours)
- 485 AH * 24 volts * 0.85 inverter eff * 1/5 hour discharge rate = 1,979 Watts maximum short term draw (minutes to an hour or so)
I think the reason I went with the 3000 model and not the 2000, was to have the capacity to cook for short periods if need be; i.e run one ring on the hob (1000W?) and a toaster (1000W?) and a microwave (700W), albeit for short periods (less than 3 minutes all together like that. The dishwasher is about 1300W, and would be nice to be able to use this occasionally too.
Also, larger inverters "waste" more power with small loads... A small inverter may draw 6-10 Watts just "turned on"... A large inverter may draw 20-40 Watts or more just "turned on"... That can be a significant amount of load for a small system (if you leave the inverter turned on 24 hours per day to charge cell phone, run lights, etc.):- 30 Watts * 24 hours = 720 WH per day just with a large inverter on 24 hours per day and no loads (almost 1/3 of your daily load budget in this example)
Yes, although not sure if the Victron has a low consumption mode (as we'd be out most days), or can I be bothered to run upstairs and turn it off?!
Next--Solar array sizing. Based on battery size, we suggest that 5% to 13% rate of charge is good for solar... 5% for a weekend cabin, and >~10% rate of charge for a full time off grid home. 13% is usually around the cost effective array size (wasted capacity):- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 913 Watt array minimum
- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 1,827 Watt array nominal
- 485 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 2,375 Watt array "cost effective" maximum
http://solarelectricityhandbook.com/solar-irradiance.html
Palma
Average Solar Insolation figures
Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
(For best year-round performance)
Jan
Feb
Mar
Apr
May
Jun
4.19
4.84
5.90
6.37
6.35
6.62
Jul
Aug
Sep
Oct
Nov
Dec
6.82
6.66
6.00
5.27
4.06
3.87
It looks like 4.0 hours of sun minimum per day will cover most of the year:- 2,474 Watt*Hours per day * 1/0.52 end to end system eff * 1/4.0 hours of sun per day average = 1,189 Watt solar array minimum (to meet load guesstimate)
Just to get up and running, I can install 2 panels on the terrace very easily. 2 more could go on the roof, but access and permission is more tricky. Presumably, if we are careful with our power demand, 2 panels, could, in the short term, keep these batteries topped up? Also bear in mind that we only use this flat for about 8 weeks of the year, the rest of the time it is vacant, although it would be nice to rent it a bit, to understanding friends, family.....
All heating is done by gas, so no worries there.
The above system (with the larger solar array) would pretty much run your home very nicely. And with conservation, you might find a small electric refrigerator that could even live on that system too.
Everybody has their "needs"... With the size system you are looking at, an 800-1,200 Watt kettle would not be a big problem.
Yes, I think we may have to swap the kettle for a lower powered one if we go down to a 2000W inverter. The 3000W was not that much more expensive so I figured it was wise to over spec. Maybe if I can find out about a low consumption mode.....
Your thoughts?
See above, and may thanks again! Palma is so sunny (300 days per year), it seems a tragedy not to use it in some way!
-Bill
See above -
Forgot to mention - the fridge is small, and has no freezer. Not sure on consumption, but it is at least quite recent (less than 2 years old).
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It would seem that the 24V Victron 3000 uses 15W at 'zero-load power' and is 94% efficient (max). The 2000 uses 10W, so I figure the 5W cost is worth it?
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bernithebiker wrote: »It would seem that the 24V Victron 3000 uses 15W at 'zero-load power' and is 94% efficient (max). The 2000 uses 10W, so I figure the 5W cost is worth it?
While your inverter is running is when you will get the biggest hit. So the 1000w difference at 6% would be 60w. The documentation on these types of items does not always make it easy to figure out these sorts of things, and my example is just that ... an example.
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Remember that the batter is the "heart" of your system... You can hang a 10,000 watt inverter on your 4x battery bank and still only get around 2,000 watts reliably out of them.
And remember, that batteries age, so when you might get 3kWatt peak from a new set with 100% charge--4 years down the road and 70% state of charge you may not... And you would want those batteries to last 5-8 years or so--Not have to replace them in a few years because they do not support your loads any more.
And--I would highly suggest the 5% minimum rate of charge--There are a lot of reasons we pick this number--And with a lower rate, you may end up with very short battery life.
Solar has its limitations--And one of them is it is very expensive to build a "large" solar system--And if you only use it 2 months out of the year, your payback (return on investment) is very poor. Especially if you are expecting utility power in 6 months.
Personally, I would highly suggest a propane (or other fuel) temporary stove (even something made for camping). Use it for a few months and put it in storage when utility power is brought to the property. Do not install a solar system that will run your loads for 10+ years only to mothball it after 2-6 months of use.
This sounds more like a condo than standalone vacation home--I assume that running a small Honda eu10i, 20i, or similar genset is out of the question?
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Remember that the batter is the "heart" of your system... You can hang a 10,000 watt inverter on your 4x battery bank and still only get around 2,000 watts reliably out of them.
And remember, that batteries age, so when you might get 3kWatt peak from a new set with 100% charge--4 years down the road and 70% state of charge you may not... And you would want those batteries to last 5-8 years or so--Not have to replace them in a few years because they do not support your loads any more.
And--I would highly suggest the 5% minimum rate of charge--There are a lot of reasons we pick this number--And with a lower rate, you may end up with very short battery life.
Solar has its limitations--And one of them is it is very expensive to build a "large" solar system--And if you only use it 2 months out of the year, your payback (return on investment) is very poor. Especially if you are expecting utility power in 6 months.
Personally, I would highly suggest a propane (or other fuel) temporary stove (even something made for camping). Use it for a few months and put it in storage when utility power is brought to the property. Do not install a solar system that will run your loads for 10+ years only to mothball it after 2-6 months of use.
This sounds more like a condo than standalone vacation home--I assume that running a small Honda eu10i, 20i, or similar genset is out of the question?
-Bill
Thanks again Bill, useful stuff.
It's a flat in an old (parts date to 16th century) building of 5 flats in old town Palma, so a generator is a tough one, too noisy, although on the terrace, for short periods, to charge batteries.....maybe we'd get away with it....! Not sure.
The 6 months is a wild guesstimate - it could be up to 2 years. There is a mountain of red tape to wade through so it's hard to tell.
Victron do make a 24V/3000V called a Multiplus that accepts a generator input - maybe this is the way to go?
Or maybe I should just order 4 panels and try to get the extra 2 installed right from the start.
Or go back to the original 'emergency' idea of the Minijoule combined unit. (200W panel, 1500W inv. 100Ah battery).
It's very confusing!
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Quick question;
Let's assume it's full sun and the 2 panels are producing their rated 560W (is it possible they might produce more?).
I am running a 500W appliance in the house.
Am I right in saying that the batteries are being 'bypassed' as in the power is coming directly from the panels, or are the batteries providing the power and the MPPT slowly recharging them? -
Noon time--Panels typically produce:
560 Watts * 0.77 panel+controller derating = 431 Watts
431 Watts / 29 volts charging = 14.9 Amps
431 Watts from solar array * 0.85 AC inverter eff = 366 Watts to AC load from panels.
You are correct, if the batteries are full, the solar array+charge controller will supply the current needed to run the loads (and float the battery bank if any current left over).
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Thank you.
The 0.77 panel + controller derating is a loss adjuster for losses in the panels / wiring / and controller? Does it really lose nearly a quarter of it's power before it gets to the batteries?
So if we neglect inverter losses (15W against 10W, (3000 vs 2000), and assume that we only use high powers (toaster, kettle) very sporadically and for very short periods, and are careful to never discharge the batteries below 75% ish, is this system workable? (With 2 panels, + 2 later). Put aside the cost for the moment, just, is it workable?! -
bernithebiker wrote: »is this system workable? (With 2 panels, + 2 later). Put aside the cost for the moment, just, is it workable?!
Not if it's the system I think it is. Bill pointed out in his first post in this thread that a 913 watt array is the bare minimum for the batteries you are proposing.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Don't use a smaller than 5% array unless you plan on using a generator or other power source. 2.5% rate of charge is not enough.
Yes, you lose that much power. And another 20% loss for cycling the battery for night time loads.
How much energy do you wish to use daily? What months will you be there?
A kill - a - watt type meter can make these measurements very easily.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Aint solar just fun! The key these days to happy systems is lots of PV. Cant make it, cant use it.1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar -
Don't use a smaller than 5% array unless you plan on using a generator or other power source. 2.5% rate of charge is not enough.
Yes, you lose that much power. And another 20% loss for cycling the battery for night time loads.
How much energy do you wish to use daily? What months will you be there?
A kill - a - watt type meter can make these measurements very easily.
-Bill
OK, I am absorbing the bad news here. But we are in a tight spot. We have no access to mains electricity for the forseeable future and we need to use the apartment, albeit only for a few weeks.
I need to be there (I work as a cycle guide) for the first 2 weeks of October, then the whole family for 1 week at Xmas.
I can fit 2 panels now but 2 more is not really possible this year - it's complicated.
As for energy required daily, well, I can get by using the bare minimum if need be. I would just like some hot water (gas), cold milk, a bit of light and a phone recharge. I can boil water on a small Primus stove, and eat out.
So fridge is 50W x 24 = 1200,
Gas boiler = next to nothing, 50?
Lights LED= 200
Phone/computer charge = 200?
So less than 2000W per day.
Maybe in that case, I can use a smaller inverter (even though it only saves 300E), and maybe even less batteries? -
Forgot inverter itself at 10 x 24 ('search mode' is 5W) = 240, but still, theoretically is less than 2kW / day.
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bernithebiker wrote: »So less than 2000W per day.
Maybe in that case, I can use a smaller inverter (even though it only saves 300E), and maybe even less batteries?
You are still trying to get something for nothing... Those two panels just won't produce enough energy for your loads. You will ruin your batteries.
Your comment: "and maybe even less batteries?" is something to think about. You could bring your system into balance by using less battery.... match your battery to your charging current. If you go that route, you MAY still have a problem... your small, but balanced system MAY not be large enough to provide for your minimal needs. How many cloudy days in a row can you have in Spain?
--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
You are still trying to get something for nothing... Those two panels just won't produce enough energy for your loads. You will ruin your batteries.
Your comment: "and maybe even less batteries?" is something to think about. You could bring your system into balance by using less battery.... match your battery to your charging current. If you go that route, you MAY still have a problem... your small, but balanced system MAY not be large enough to provide for your minimal needs. How many cloudy days in a row can you have in Spain?
--vtMaps
Majorca is pretty much the sunniest place (island) in a very sunny country, which helps.
Given that we had been considering 'camping' at the flat with no electricity at all, then some is better than none. This was why I initially considered the MiniJoule Island, a self-contained unit with 1500W inverter and 100Ah battery, fed by a 200W panel.
But this is 1400 Euros. I just re-priced a simpler 'a la carte' system, with 2 x 285W panels, 2000W inverter (down from 3000) and 2 x 200Ah 12V batteries, (down from the 4 x 6V Rolls) and this comes to a bit less than 2000 Euros. So the latter is better as it is higher performance all round, and can be added to in the future, which the Minijoule cannot.
Personally I can live without pretty much everything if need be; except hot water - the thought of a cold shower fills me with dread, so as long as I can power the boiler, I'm happy. If I can add bits and bobs like the fridge and some lights, then great. -
The self contained system with a 200 watt inverter, 100 AH battery bank, and a 1,500 Watt AC inverter is still "unbalanced)... Realistically, a 100 AH 12 volt battery would practically be around a 250 Watt AC inverter maximum. Yes, if the battery is an AGM (or Li Ion) that can supply better surge current--The total storage capacity is:
- 12 volts * 100 AH = 1,200 Watt*Hours of storage.
A system with 200 Watts of solar panel in December would produce:- 200 Watt * 0.52 end to end system eff * 3.87 Hours of sun for an average December day = 402 Watt*Hour per average December day
13 Watt LED fixture * 3 fixtures * 10 hours per night = 390 Watt*Hours per night
That is pretty much it... Perhaps you can charge a cell phone too.
The math just does not work out any other way...
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
The self contained system with a 200 watt inverter, 100 AH battery bank, and a 1,500 Watt AC inverter is still "unbalanced)... Realistically, a 100 AH 12 volt battery would practically be around a 250 Watt AC inverter maximum. Yes, if the battery is an AGM (or Li Ion) that can supply better surge current--The total storage capacity is:
- 12 volts * 100 AH = 1,200 Watt*Hours of storage.
A system with 200 Watts of solar panel in December would produce:- 200 Watt * 0.52 end to end system eff * 3.87 Hours of sun for an average December day = 402 Watt*Hour per average December day
13 Watt LED fixture * 3 fixtures * 10 hours per night = 390 Watt*Hours per night
That is pretty much it... Perhaps you can charge a cell phone too.
The math just does not work out any other way...
-Bill
OK no problem, I had pretty much rejected that option anyway.
What do you think to my new 'pared' down system? (Coupled with pared down consumption!) -
bernithebiker wrote: »OK, I am absorbing the bad news here. But we are in a tight spot. We have no access to mains electricity for the forseeable future and we need to use the apartment, albeit only for a few weeks.
I need to be there (I work as a cycle guide) for the first 2 weeks of October, then the whole family for 1 week at Xmas.
I can fit 2 panels now but 2 more is not really possible this year - it's complicated.
As for energy required daily, well, I can get by using the bare minimum if need be. I would just like some hot water (gas), cold milk, a bit of light and a phone recharge. I can boil water on a small Primus stove, and eat out.
So fridge is 50W x 24 = 1200,
Gas boiler = next to nothing, 50?
Lights LED= 200
Phone/computer charge = 200?
So less than 2000W per day.
Maybe in that case, I can use a smaller inverter (even though it only saves 300E), and maybe even less batteries?
Sorry to be pedantic--But:- Watts = "Rate" -- Like miles per hour
- Watts*Hours = "Amount" -- Like miles driven
"2,000 Watts per day" is actually 2,000 Watt*Hours per day.
If you want that much average power per day, for a 2 day storage (bad weather) and 50% maximum discharge:- 2,000 Watt*Hours * 1/0.85 AC inverter efficiency * 1/24 volt battery bank * 2 days storage * 1/0.50 max discharge = 392 AH @ 24 volt battery bank
- 2,000 WH per day * 1/0.52 off grid system eff * 1/3.87 hours of average sun in December = 993 Watt array minimum
- 2 * 260 Watt panels * 1/12 volt battery bank * 0.77 panel+controller derating * 1/0.05 rate of charge = 667 AH @ 12 volt (or 334 AH @ 24 volt) battery bank maximum size
- 2 * 260 Watt panels * 1/12 volt battery bank * 0.77 panel+controller derating * 1/0.10 rate of charge = 334 @ 12 volt nominal size bank
- 2 * 260 Watt panels * 1/12 volt battery bank * 0.77 panel+controller derating * 1/0.13 rate of charge = 257 AH @ 12 volt battery bank minimum
- 2 * 260 Watt panel * 0.52 DC solar system eff * 3.87 hours of sun per average Dec day = 1,046 Watt*Hours per day
So fridge is 50W x 24 = 1200,
Gas boiler = next to nothing, 50?
Lights LED= 200
Phone/computer charge = 200?
Fridge--Out. Lights+Phone= 400 Watt*Hours per day--Lots of extra power available (1,046 WH - 400 WH per day used = 646 WH of "extra" energy).
I would look at a 12 volt @ ~257 to 334 AH battery bank and a MorningStar or similar 300 Watt TSW inverter @ 12 volts--There is a 230 VAC 50 Hz version available.
http://www.morningstarcorp.com/products/suresine/
A thought--If you can get "golf cart" batteries (6 volt @ ~200 AH) in your region for a good price--I would connect 2x in series, and 2x parallel strings (4 batteries total give you a ~400 AH @ 12 volt battery bank)--Would fine OK for a weekend/seasonal place.
Or if your loads are really 400 WH per day, then just 2x 6 volt GC batteries with the 2x 260 Watt panels... A bit over paneled--But you can certainly use the power (run computer+cell chargers during daytime) with those batteries.
Assume the batteries will last you 3-5 years if you take good care of them... Or ~2 years or less if not (most people murder their first or two sets of batteries anyway--Living off grid is a learning experience--And why we suggest going "cheap" with the first set or two of batteries--Almost everyone kills the first ones).
2x 260 Watt solar panels
1x MPPT type charge controller (30 amp minimum--MPPT controllers are more expensive but needed here)
2 to 4x 6 volt golf cart batteries
1x MorningStar or similar 300 Watt @ 12 vdc TSW inverter with 230 VAC @ 50 Hz output
Wiring + circuit breaker(s) + battery box (keep batteries safe from kids with metal objects)
1x Hydrometer (US source, find European vendor)
1x Digital Volt Meter (I really like a DC Current Clamp DMM like this one--Maybe in the future)
1x 230 VAC Kill-a-Watt type Watt*Hour meter
Misc. hardware (roof mount, screws, cable ends/ring lugs, bus bars, etc.).
What people sometime do--Get a piece of 2'x3' plywood--Mount the charge controller+AC inverter+breakers+bus bars+etc. to the board. Setup battery bank + solar array in your yard at home--Wire up and test for a few days, make sure it all works... Disconnect array+battery bank and haul to installation site.
Just to give you an idea what a small system can look like--poster 2manytoyz has documented his evolution with lots of photographs:
http://2manytoyz.com/
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
For four weeks, have you considered a generator?1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar -
For four weeks, have you considered a generator?
Hi - it's a lot more than 4 weeks, and a generator would be too noisy (neighbours). thanks -
bernithebiker wrote: »
Hi - it's a lot more than 4 weeks, and a generator would be too noisy (neighbours). thanks
What do you neighbors do for their electricity? If they are close enough to hear your genny, they must have a solution. Live like the natives for 6 months. -
ie. Run a power cord from the neighbours....
Re 0.05C charge rate. I wouldnt do it. Solar is all about balance, the reason a 0.1C charge rate works so well (other than that batteries like it) is that coincidentally it means that you can fully recharge the battery in a single day. Allowing for charge effciency a 0.1C charge rate takes about 14 hours for 100%DOD but we only run 25% DOD as a daily rule, so a quarter of 14 is 3.5hrs. Which just conveniently happens to be the average sun hours per day in most places.
Solar costs a fair bit, and... takes a bucket load of time to learn. Dont under estimate that.1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar -
The neighbours have mains, but we don't. It's a complicated, red tape thing, to do with meter norms, etc. Our meter was taken away by the previous non-paying owners. Now we want a new one, they don't like the communal meter arrangement. Needs work to comply. But neighbours won't pay their share.....voila....!
So maybe could trail a lead from a friendly neighbour, but would prefer something more independent.
I'm going to go with the the 2000W Victron inverter, 2 x 285 panels (with the hope of adding more soon), 2 x 200Ah 12V batteries, the MPPT mentioned above, and a remote monitor dial. 2000 euros.
With a gas stove, and very limited elec. use, I'm hoping we'll get by for the time being. -
bernithebiker wrote: »The neighbours have mains, but we don't. It's a complicated, red tape thing, to do with meter norms, etc. Our meter was taken away by the previous non-paying owners. Now we want a new one, they don't like the communal meter arrangement. Needs work to comply. But neighbours won't pay their share.....voila....!
So maybe could trail a lead from a friendly neighbour, but would prefer something more independent.
I'm going to go with the the 2000W Victron inverter, 2 x 285 panels (with the hope of adding more soon), 2 x 200Ah 12V batteries, the MPPT mentioned above, and a remote monitor dial. 2000 euros.
With a gas stove, and very limited elec. use, I'm hoping we'll get by for the time being.
Getting there. But reread what bill said about battery to inverter ratio...
To support the current requirements of the inverter a battery needs to have 400Ah of capacity per kilowatt of inverter (12V), thus the victron, needs 800Ah. Without it, the voltage will sag, and the inverter shutdown. If you dont get this, read the inverter manual. With inverters the exact opposite of "bigger is better" applies. Counter intuituive i know.
I really think you have better solutions available to you. Take the 2000 bucks and give it the neighbour, run a lead, for all the power can you can ever need or use.1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar
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