Request opinion on a new Solar system parallel with electric grid

emanuf
emanuf Registered Users Posts: 3
in Solar Beginners Corner #1
Hello
I’m writing from Portugal (100 Km north from Lisbon) and i’m planning to install solar panels, battery supported, in order to cut my energy account and preserve some independency from the electric grid. Big problem for now is that i'm really new to this things and i've been collecting info from suppliers... and what comes from the Internet, but in this case usually is very technical... and over here it seems that you explain stuff in a very clear way...

My consumptions are about 5.500 kW / year, half during the day (mostly on weekends or when air conditioning is needed) and half during the night (dish and laundry washers); also have the water heating (460 W)…
I have 2 proposals.
1. First Proposal:
a. 12 panels PANASONIC HIT N240 (in series of 2, 6 strings)
b. 1 Inverter SMA SB 4000TL
c. 1 Sunny Island SI 6.0H
d. 8 batteries EXIDE GEL 12V 230A/h (4 in series x 2 in parallel)
e. 1 Regulator Outback FlexMax 80
2. Second proposal:
a. 8 panels PANASONIC HIT N240 (in series of 2, 4 strings)
b. 1 Inverter SMA SB 4000TL
c. 1 Sunny Island SI 6.0H
d. 4 batteries EXIDE GEL 12V 230A/h (2 in series x 2 in parallel)
e. 1 Regulator Outback FlexMax 80
f. 1 wind generator 1000W and the regulator SMA Windy Boy 1200

Solar panels will be divided in 2 different orientations: S-SE and S-SW. Where I live we have lots of sun and it can be windy sometimes (many times…). Temperatures can go up as +40 C and lower as -3 C (usually for a few days and in the morning, when the sun comes it goes to positive values)…
I don’t pretend to substitute totally the electric grid supply, but I do want to be certain that I can live without it if need it.

What I’d like to ask your opinion is about:
1. With the Sunny Island do I need the Outback FlexMax?
2. Having both proposals almost the same value, which one is preferable?
3. Does the wind generator contributes for a higher “use” of batteries, especially during the night (with charge / discharge, resulting of having wind and not).
4. With this equipment can I have a good control not to let excessive production to flow out to the electric grid? (no consumption and batteries at 100% with a sunny day)
Thanks for your opinion.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,622 admin
    #2
    Re: Request opinion on a new Solar system parallel with electric grid
    emanuf wrote: »
    I’m writing from Portugal (100 Km north from Lisbon) and i’m planning to install solar panels, battery supported, in order to cut my energy account and preserve some independency from the electric grid. Big problem for now is that i'm really new to this things and i've been collecting info from suppliers... and what comes from the Internet, but in this case usually is very technical... and over here it seems that you explain stuff in a very clear way...

    My consumptions are about 5.500 kW / year, half during the day (mostly on weekends or when air conditioning is needed) and half during the night (dish and laundry washers); also have the water heating (460 W)

    Welcome to the forum and a couple of quick questions...

    5.500 kW per year.... Many countries swap "." for "," in numbers... Also, I think you mean kWatt*Hours per year... I (in the US) would write that as:

    5,500 kWH per year (for me 5.500 would be 5.5)

    Next, with solar, realistically, yearly usage/generation numbers are not real useful for off grid systems. Generally, we can only store around 1-3 days of energy in the battery bank on site... So, knowing your daily loads (sometimes seasonal--like Air Conditioning + Water irrigation in summer, and none of that in winter).

    5,500 kWH per year / 365 days per year = 15 kWH per day (average)

    That is not a lot of energy (the average north American and many European homes is probably on the order of ~33 kWH per day).

    However, for off grid solar--That is a fair amount of power and is not a small system... A minimal sized system (no-A/C) would probably be closer to 3.3 kWH per day (refrigerator, lights, clothes washer, well pump, laptop computer, efficient TV). And that would reduce your installation costs to 20% of a 15 kWH per day system.

    If you need a 15kWH per day system--That is fine--Just want to confirm.

    Also, do you have any information how many hours per day of noontime equivalent sun per day (or kWH per sq.meter per day) by season/month you get? That will help to size the system too.

    Are you planning on keeping the grid connection, or disconnecting and using a generator?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • emanuf
    emanuf Registered Users Posts: 3
    #3
    Re: Request opinion on a new Solar system parallel with electric grid

    Hi Bill

    About the numbers, over here "." separates the thousands and the "," separates decimals... but you are correct, last year i spent around 5,500 kWH (that is five thousand and five hundred)... but in 2011 i spent a little bit more than 6,000 kWH. This here we had very hot days (+40C... +42C) but only for 5 to 7 days, than temperatures went down to +30C... i've been saving in air conditioning.

    As you say, my average goes around those 15 kWH per day. But i've just checked in weekly registers i've been making: from may until now my daily average is around 10kWH... but with air conditioning working (especially during the afternoon, from 1pm to 6pm and that happened the previous week and on the first week of july) daily average can go up to 16 kWH...
    Of course that this means tha in winter i would probably spend around 20 to 30 kWH daily...

    But i want to keep the grid connection and i'm thinking on keeping air conditioning direct to the grid... I dont' have a well and i would have to programme machines (laundry and dishes) to work during the day as ooposite to now where they work during the night (cheaper).
    The ideia is to have a system that can hold basic stuff (refrigerator, lights, laptop computer, efficient TV) for one day and night in case of grid failure... thant's why there are batteries; if its a sunny day, so it should also be able to wash clothes :). Meanwhile I do want to be able to get some return from the investment on the daily basis... but as I said, keeping the grid.

    About the sun, my coordinates are: Lat 39.47 Long -8.47.
    I dont' know if this is what you want: https://eosweb.larc.nasa.gov/cgi-bin/sse/retscreen.cgi?email=rets%40nrcan.gc.ca&step=1&lat=39.47&lon=-8.47&submit=Submit (I just think that this teperatures and wind speeds are... very different from reallity...)
    One of the suppliers gave me a report; it seems made with a software called PVSYST v5.55 and it has this values:
    Attachment not found.

    I hope this can help you helpping me. :)
    Thanks.
    Emanuel
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #4
    Re: Request opinion on a new Solar system parallel with electric grid
    emanuf wrote: »
    What I’d like to ask your opinion is about:
    1. With the Sunny Island do I need the Outback FlexMax?

    If you use a Sunny Island + Sunny boy, then you don't need the flexmax. If you choose not to install the sunny boy, then you can use a Flexmax. Either:
    SI + SB or
    SI + flexmax.

    SI + SB + Flexmax makes no sense.
    emanuf wrote: »
    2. Having both proposals almost the same value, which one is preferable?

    Neither, they both spec extremely expensive super-efficient panels which you don't need unless you have very little roof space. The second one has an unnecessary flexmax. And both include crappy 12v gel batteries which are expensive and won't last very long in cycle applications.
    emanuf wrote: »
    3. Does the wind generator contributes for a higher “use” of batteries, especially during the night (with charge / discharge, resulting of having wind and not).

    Any additional charging sources will reduce your use of the batteries. The question is whether it's an economical charging source or not. Wind is tricky because of expensive quality wind turbines and high maintenance cost. Solar is more reliable and a provides more kWh/installed cost. In any case their proposal to use a windyboy is ludicrously expensive for a small turbine.
    emanuf wrote: »
    4. With this equipment can I have a good control not to let excessive production to flow out to the electric grid? (no consumption and batteries at 100% with a sunny day)
    Thanks for your opinion.

    Yes the sunny island will fully control this for you, you can tell it when to use the batteries and when to start charging from the grid (based on the battery state of charge and/or time of day and/or current draw).

    IMO an ideal cost effective system would be:
    - Chinese panels from a top manufacturer: (Canadian solar, Yingli, Trina, Suntech) or even LDK, Jinko.
    - SMA sunny island
    - Outback flexmax 80 (to allow for future expansion), or a midnite solar classic (also 80A at 48V).
    - PzS forklift batteries. These are designed for heavy and deep daily discharges. They will likely be 1/3rd or 1/2 cost of the gels, but they gas so must be installed outside or with very good ventilation. You'll need to check the water level every 3 months or so.

    If you went for 12 panels, then the total cost of the above should be under 12k euros.

    Since you have a grid connection to make up for any deficit in charging the number of panels you install is really up to you. Here's an interactive tool that'll help you decide on the number of panels: http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php#
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  • emanuf
    emanuf Registered Users Posts: 3
    #5
    Re: Request opinion on a new Solar system parallel with electric grid

    Hi sthependv

    I thought that the option was between Sunny Island and FlexMax and not between SunnyBoy and FlexMax; didn't know you could connect the solar panels to SI ou FM...
    About the batteries, I can't have them "outside"... and i'd the opinion that gel batteries would last longer than the lead-acid ones...

    The price you give (12k euros) does it include instalation and configuration and taxes?

    The link ou sent is seems a very good one... problem is, i don´t know how to calculate some of the variables
    Thanks
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #6
    Re: Request opinion on a new Solar system parallel with electric grid
    emanuf wrote: »
    I thought that the option was between Sunny Island and FlexMax and not between SunnyBoy and FlexMax; didn't know you could connect the solar panels to SI ou FM...

    The sunny island is a battery inverter + AC charger. Then the option is to either connect the panels to the sunny boy, and the sunny boy feeds AC power into the sunny island, which charges the batteries. Or solar panels connected to the flexmax, which charges the batteries directly.
    emanuf wrote: »
    About the batteries, I can't have them "outside"... and i'd the opinion that gel batteries would last longer than the lead-acid ones...

    They are both lead acid, except the gels don't have liquid electrolyte. Since there's no liquid, if you accidentally overcharge then there's no way to replace the electrolyte. With flooded lead acids, it's just a matter of adding water. It's also possible to measure the state of charge accurately with flooded bats with a hydrometer. Plus the gels tend to be much more expensive.
    The flooded bats just need to be in a well ventilated space, they don't have to be literally outside.
    emanuf wrote: »
    The price you give (12k euros) does it include instalation and configuration and taxes?

    The link ou sent is seems a very good one... problem is, i don´t know how to calculate some of the variables
    Thanks

    Price was a finger in the air estimate, without instalation:
    - Sunny Island about 3k
    - 3kW of solar about 3k
    - 700Ah/48 forklift battery about 4k
    - Midnite classic or flexmax about 600 euros
    - Cabling, mounting and breakers about 1k

    So around 11k rough estimate.

    With the link, you just need to choose your location, and enter the installed kW, then select the orientation and inclination- you can leave everything else as-is.
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