New solar set-up after 3 months of use

[Insequent]

Hello Brian,

We love solar too we now have 10X 330Watt BenQ panel and soon going to had 8 more all most 6Kw of solar that going to be wonderful (We live full time onboard and never shore-power so solar make sens)

could you tell me price of you 345Watt Sunpower panel?

Hugues

They are expensive here in Australia (like lots of things.....) and were US$560 each at current exchange rates.

I'm a fan of having as many panels as possible. But even with only 6 x 345W I don't connect shore power at the dock unless there are cloudy days.

 

[101TUG]

They are expensive here in Australia (like lots of things.....) and were US$560 each at current exchange rates.

I'm a fan of having as many panels as possible. But even with only 6 x 345W I don't connect shore power at the dock unless there are cloudy days.

Thanks Brian, yes I can Imagine 6X 345W that plenty of power

 

[CraigC]

I HOPE it doesn't make TOO much difference that your latitude is around 27 degrees, and mine is 37 (like the border of NSW and Victoria).... But then, in my wintertimes here, it's much more unusual to be cruising for any lengths of time, as our seas are generally much less friendly in winter. Like, how's the cruising out of Bairnsdale in June? Nice easy run to Hobart, then, I am sure... Or not.

The Sunpower cells seem like they would do pretty well in lower light, anyway. You could maybe comment on winter vs summer performance... Or, would you be designing your system differently if you were a liveaboard in Bairnsdale or Melbourne.... They are roughly equivalent to where I will be living aboard, except I am directly on your East Coast... more like Bairnsdale I guess.

 

[Arch]

Brian,
Why not run the water heater? A small 750 watt heater run for half an hour for shower and dishes would only take 35 AMPs or so. It would be the difference between cold water camping and a comfortable life ��
I agree, unlimited hot water would be too much.
Arch

 

[CraigC]

I believe the 30 gallon WH in my boat has a heating element around 3500-3800 watts... So does that mean for one hour I would use 3800/12 = 316 amps? and for 10 minutes, divide by 6, so about 53 amps used? But then, a tank keeps the water hot all the time, so it would be just a flat continuous 316 amps/hour...? Oh, tank heating element runs intermittently, so I would have to look at the specs of the unit itself, eh?

 

[BruceK]

You could spend hours identifying the HWS model you have, calculating heating amps,heat time required, temp retention period, reheat time/amps/cost, etc etc. Or, one frosty morning you could offer Mrs CraigC a cold shower, whereupon you will likely get instant direct advice to just power up the HWS.

 

[Insequent]

Brian,
Why not run the water heater? A small 750 watt heater run for half an hour for shower and dishes would only take 35 AMPs or so. It would be the difference between cold water camping and a comfortable life ��
I agree, unlimited hot water would be too much.
Arch

For hot water I have engine an engine heating loop as well as shore power. But in addition I have another loop with the Webasto hydronic heating system. If I need heat for the boat then I run the normal heating system loop and also make hot water. But if I just want hot water I change the valves to 'summer loop', which gives hot water without going through the hydronic heating circuit. So, I'm never going to be out of hot water, and no need to divert solar Ah for water heating.

 

[Insequent]

I believe the 30 gallon WH in my boat has a heating element around 3500-3800 watts... So does that mean for one hour I would use 3800/12 = 316 amps? and for 10 minutes, divide by 6, so about 53 amps used? But then, a tank keeps the water hot all the time, so it would be just a flat continuous 316 amps/hour...? Oh, tank heating element runs intermittently, so I would have to look at the specs of the unit itself, eh?

You have a relatively large HW tank, and 3500W + would be a large heating element as well. On USA shore power that'g going to get near 30A draw. My 20 gallon tank has a 1500W element, which is suspect is more typical.

Even with a 1500W element it would take a quite a chunk out of the house bank's capacity - say 60-70 Ah for 30 minutes of heating. I could probably cope with that, but just don't need to given other options to make hot water. However, my boat is wired so that I cannot heat water or run battery chargers off the inverter anyway.

 

[CraigC]

As it turns out, it is a 20-gal tank, per the survey. My guess is it is also 1500W. I will head over there tomorrow and check it out, find out what make and how old it is, and the draw. I still have a lot to learn about the boat, obviously..

Annoyingly, the WH has been moved about as far away from the heads as it could get, too.

I have started on that spreadsheet! Since I have no Mrs CraigC (yet), Ms. Excel will need to be the stand-in..

 

[Simi 60]

According to all your inputs, looks like this solar project is going to cost me around US$15,000.

Doest have to cost anything like that.
My victron inverter was $3k
Batteries were the same $3k
Victron batt monitor $200
Midnight Mppt was $750 delivered on ebay
250 watt Jinko panels were something like $140 each delivered ( tier 1 company 2nd hand panels but 9.5 years of warranty left)
A few hours of electricians wages to wire up and it all comes to less than $7000 usd

Household hws does use juice, but not as much as you may think.
when it is running during the day I still have + amps going in via solar, so panels generating more than hws uses.

 

[CraigC]

Thanks Simi. Yeah I think with a 5000VA inverter and enough batteries, the hws might be okay on the system.

I had the inverter priced at $2500, the panels at $2500 (about $1.25/watt, because I have yet to find the Sunpower mono 330W panel modules in the US (need 6 of them), so price is unknown), the Lifeline batteries at $4200 (padded this because my current four house gel cells are 10+ years old and I was thinking I might want to keep the current Freedom 20 Heart with the genset and a 2nd bank to use for the windlass etc as Brian has), the controller and the 702 at $800, that makes $10,000. Guess I could use cheaper batteries for the second house bank. The solar array would be replacing my second generator - I think I would move the NL genset in where the Onan is, and let the mechanic take the Onan for parts, so I presumed that reorganization would involve some wiring changes into my electrical load center/panel. I might be making too much of that. Plus 9.5% tax, misc materials, labor, and also moving some other things around, adding a Washer/Dryer, stuff like that.

The Odyssey 214ah batteries are less expensive than the 255ah Lifelines, but the installer sells Lifeline, so that's kind of what I need to use.

 

[Insequent]

My winter/spring cruise data, posted at the start of the thread, was quite good. Once summer arrived I was curious as to how much more output I would get. Mostly from longer daylight hours and sun angle being more overhead.

I have not anchored out for days at a time that much, but do see a pattern emerging. Max output (amps or watts) is similar to when I was on the extended cruise and the atmosphere was 'normal'. That is, particulates or smog not cleaned off by some rain. Overall Ah for a day is up and typically around the cruise maximum.

But yesterday was a new high - 806 Ah generated for the day even with the controller in 'float' mode for 3:15 hours. I'm hoping for some rain and clear skies thereafter at the weekend, and plan on running the washer and dryer for a bit to 'make some space' in the battery bank for a full day of solar generation, just to see how high it can get. The SunPower 345W panels continue to be amazing!

 

[twistedtree]

So if my math is right, that's 10kwh extracted, or the equivalent of 5hrs at full power on your 2kw array. Does that sound right? I'd say that's really good if it's correct.

 

[BruceK]

With that output,the Marina will be plugging into your boat, rather than the other way around. What a great successful system.

 

[Insequent]

So if my math is right, that's 10kwh extracted, or the equivalent of 5hrs at full power on your 2kw array. Does that sound right? I'd say that's really good if it's correct.

Yes, 10.6 kWh on the Mate 3 log. It is good as max output was 1670W. With really clean sky I have seen max up to 2300W. Still, I'm pretty happy.

 

[Insequent]

With that output,the Marina will be plugging into your boat, rather than the other way around. What a great successful system.

As often as not I don't plug into the marina at all. I think its likely better for the panels to be working rather than 'throttled back'. Do they age prematurely if they can't fully produce what they are capable of?

 

[BruceK]

As often as not I don't plug into the marina at all. I think its likely better for the panels to be working rather than 'throttled back'. Do they age prematurely if they can't fully produce what they are capable of?

With a much more modest set of panels we only leave the power connected for particular purpose, eg. pulling down the eutectics pre cruise.
As to the benefit of using the output and "keeping them working" can the electrics experts please comment? And maybe resolve the "where does unused output go" question we touched on a while back.

 

[Insequent]

With a much more modest set of panels we only leave the power connected for particular purpose, eg. pulling down the eutectics pre cruise.
As to the benefit of using the output and "keeping them working" can the electrics experts please comment? And maybe resolve the "where does unused output go" question we touched on a while back.

Just a guess, but instead of generating electricity the irradiance likely ends up as heat. If so, do the panels become hot enough to prematurely age the cells?

 

[BruceK]

Brian, In the absence of the electrical hotshots coming in, I hit search. This is the most helpful article I found: electric circuits - Where does electricity go from a solar panel that is not plugged in to anything? - Physics Stack Exchange.
Another article suggested heat could result in cells, with potential damage. Which may confirm your intuitive "guess".

 

[Martin J]

Hi Bruce
As the panels make the juice , it goes nowhere till its drawn by the controller. Most controllers (mavericks etc)on reasonable installations (1KW) have very smart charging programes which do the whole thing Bulk, settling, float etc. This allows the panels to be ("on" constantly). I only turn mine off when working on the system or general wiring that would interfere with the solar system. I also have ACR units that allow the excessvoltage to be used to ensure all engine batteries are mainatined at optimal voltage as well, by the overspill from the solar. I lay the boat up for 2x3 months a year, 3 months of winter and 3 months of summer. All batteries are 100% when I return.

 

[BruceK]

Martin, to paraphrase the article I found: "no demand = nothing being generated".
I like coming onto the boat, no charger connected except solar,to find batts in "float".
How do you turn panels "off"? Does your regulator have an "off" control?
I remember taping black plastic over my panels to "put them to sleep" while working on the system wiring, I probably don`t need to do that.

 

[Insequent]

Bruce
I can remove the fuses, located where the panels are paralleled, to isolate them from the rest of the system wiring. I imagine your system would have fuses not far from the panels too.

 

[Martin J]

Hi Bruce
I obviously have a circuit breaker in the line and a battery disconnect.

 

[Insequent]

Yesterday was hot, clear blue sky. The city was 38°C but in the Bay it was just over 31°C. Wind direction kept the solar panels shade free until mid afternoon, and my house bank was somewhat down. With about 13 hours from sunrise to sunset, and located at 34.5°S latitude it was a good test of what the panels are capable of.

Yield for the day was 942 Ah, or 11.8 kWh. Peak panel output was 130.4A or 1650W. This is about 80% of maximum possible just after some rain has cleared the atmosphere of particulates. But still very good performance!

 

[Martin J]

Sorry Brian your numbers don't add up

942ah 12volt = 78amps
130amps 12 volt = 1560 watts (1.56KW)

 

[Bob Cofer]

This is what we are getting today

 

[Insequent]

Sorry Brian your numbers don't add up

942ah 12volt = 78amps
130amps 12 volt = 1560 watts (1.56KW)

Well the numbers I quoted were from the Mate 3 log!

To clarify a bit, the house bank isn't 12V when charging, or when fully charged, its a bit more than 12V.

Your 78 figure has units of Ah/V - not A. To get average for the day divide by 13 (daylight hours) to get 72.5. The 130A (and W output) was the 'momentary' maximum panel output at around midday.

 

[BruceK]

Bruce
I can remove the fuses, located where the panels are paralleled, to isolate them from the rest of the system wiring. I imagine your system would have fuses not far from the panels too.

My fuses are near the batts served by the panels. Good idea, I had not thought of powering off the panels that way. Especially now we discovered no demand = no generation.