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Solar panel setup


blackrose

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I'm just starting to look into solar panels for my boat. I know there's already a lot of info on the forum, but I'm finding it a bit confusing. I have a mooring with shore power but I'd like to start to run from solar as much as I can. My inverter isn't pure sine wave so can't run my washing machine but I can always plug into the mains if I need to.

 

To start with, my power audit is giving me 95 Ah/day which seems pretty high, given that I have a gas fridge, but I often work at home from the boat and I'm including 8 hours of laptop use/day. If I add in the fridge running on mains instead of gas for 12 hours/day I get 226 Ah/day. I also have a small tabletop mains freezer which draws about 9 amps DC but if I include that in the audit I think I'd need a bigger battery bank so I can do without that luxury.

 

The bit I'm finding really confusing is which type of panels to buy. I think I'd rather have rigid panels than the flexible stick down type, but they would be mounted flat on the roof, so with a daily power audit of 226 Ah can anyone advise me the best type of panels/how many watts and which controller from Bimble please? My battery bank is 3 x 150 Ah Trojans (wet lead acid).

 

Thanks

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Unless you intend to run the fridge via the inverter it as no relevance to the power audit. I would suggest shore power when in the marina and gas when cruising.

 

The freezer should not be running 24/7 because it should have a thermostat so take half the 9 x 24 figure as a guide so 108 Ah per day.

 

I doubt you stand much chance of running 100% on solar for the whole year, especially if it is a narrow boat because of roof space, so I would suggest that you don't go chasing maximum theoretical output because that will have a cost penalty. Concentrate on getting as much solar as you can fit and afford.

 

Once you get into large Ah per day figures it is probably time to start saving to eventually convert from lead acid batteries, that within minutes of charging start to limit the charging current, to LiFePO4 lithium batteries that will absorb the maximum charge you can throw at them until your system has to terminate the charging to stop the batteries being damaged by overcharging.

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9 Amps @12v = 108Watts, for your little tabletop mains freezer is very high, As you quote DC I assume you are running it on the inverter. Is it not a compressor freezer? Or does your inverter use a lot when not powering anything?

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Look at what Bimble have on their website at the moment and see what gives you the best bang for your buck - they usually have second hand panels from solar farms which have been upgraded, which are significantly cheaper than new. Work out how many you can fit on the roof and that's what to get. Add up the total panel wattage, divide by 10 and that's the current rating (for a 12V system) of controller you need. Tracer controllers (and maybe others) will take an input of up to double the rated output without damage (but won't deliver more than the rated output), so you could reduce the controller output (and cost), which will reduce the peak power available at the height of the summer, but will extend that output further into the autumn and spring.

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1 minute ago, David Mack said:

Tracer controllers (and maybe others) will take an input of up to double the rated output without damage (but won't deliver more than the rated output), so you could reduce the controller output (and cost), which will reduce the peak power available at the height of the summer, but will extend that output further into the autumn and spring.

 

And if they are  charging lead acid batteries the batteries thensellves will soon be limiting the current they accept anyway so maybe not as wasteful as it seems.

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7 minutes ago, Tony Brooks said:

Unless you intend to run the fridge via the inverter it as no relevance to the power audit. I would suggest shore power when in the marina and gas when cruising.

 

The freezer should not be running 24/7 because it should have a thermostat so take half the 9 x 24 figure as a guide so 108 Ah per day.

 

I doubt you stand much chance of running 100% on solar for the whole year, especially if it is a narrow boat because of roof space, so I would suggest that you don't go chasing maximum theoretical output because that will have a cost penalty. Concentrate on getting as much solar as you can fit and afford.

 

Once you get into large Ah per day figures it is probably time to start saving to eventually convert from lead acid batteries, that within minutes of charging start to limit the charging current, to LiFePO4 lithium batteries that will absorb the maximum charge you can throw at them until your system has to terminate the charging to stop the batteries being damaged by overcharging.

 

Ok thanks, so you don't think I can run the fridge on mains from solar panels? I already based my fridge and freezer calculations on 12 hours/day. 

 

I'm not going to change to lithium batteries.

10 minutes ago, Tracy D'arth said:

9 Amps @12v = 108Watts, for your little tabletop mains freezer is very high, As you quote DC I assume you are running it on the inverter. Is it not a compressor freezer? Or does your inverter use a lot when not powering anything?

 

Yes, 8.8 amps is what my battery monitor is showing when running the freezer from the inverter. That includes 0.6 amps for the inverter itself. I rounded up to 9 amps.

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6 minutes ago, David Mack said:

Look at what Bimble have on their website at the moment and see what gives you the best bang for your buck - they usually have second hand panels from solar farms which have been upgraded, which are significantly cheaper than new. Work out how many you can fit on the roof and that's what to get. Add up the total panel wattage, divide by 10 and that's the current rating (for a 12V system) of controller you need. Tracer controllers (and maybe others) will take an input of up to double the rated output without damage (but won't deliver more than the rated output), so you could reduce the controller output (and cost), which will reduce the peak power available at the height of the summer, but will extend that output further into the autumn and spring.

 

Thanks, it's the various panel technologies which I find confusing. Mono solar, Monocrystalline solar, Mono percium solar, etc. Are they all the same?

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Just get a kit off Bimble or another provider if you want value.

They will advise even if you have some extreme requirement, but why should you?

PS the kits don't all include inverters, they sell bits and pieces, but kits mean you get matched wiring etc

Edited by LadyG
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7 minutes ago, LadyG said:

Just get a kit off Bimble or another provider if you want value.

They will advise even if you have some extreme requirement, but why should you?

 

Thanks but kits from Bimble seem to include inverters and batteries which I don't need.

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1 hour ago, blackrose said:

 

Ok thanks, so you don't think I can run the fridge on mains from solar panels? I already based my fridge and freezer calculations on 12 hours/day. 

 

 

 

You may be able to during the summer but certainly not for the less sunny months. It all depends upon how much solar you can get on to the boat, but I doubt it even on a 72 footer. Remember within short time charging the batteries will be limiting the current, not the solar.

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2 minutes ago, Tony Brooks said:

 

You may be able to during the summer but certainly not for the less sunny months. It all depends upon how much solar you can get on to the boat, but I doubt it even on a 72 footer. Remember within short time charging the batteries will be limiting the current, not the solar.

 

Blackrose does have a 'big fatty' boat !

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Some modern fridges have a freezer compartment which can be removed or kept in place as required.

I don't see the need for a full sized freezer on the inland waterways, just stock up at Aldi  for main food and drink, then top up with bread and milk as you pass by villages. The only food I buy frozen is things like chicken burghers, fish cakes, and ice lollies, they all come in small packets and are consumed within days.

It's not a good idea to buy fresh food and then freeze it, there is no cost saving and it's not going to be as good as frozen foods. Unless you are thinking of bringing frozen ready meals from home, to cut out cooking on the boat?

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50 minutes ago, LadyG said:

Look again

 

I looked again. The kits seem to limit my options because some come with stuff that I don't need. Also it's easy to say "just get a kit" but my original question still remains. Which particular panels within those kits are you recommending?

 

23 minutes ago, Alan de Enfield said:

 

You can mix-n-match with Bimble.

You can say I don't want X, but I need 2x as much cable, and make the Panels 345 w instead of 250 w. etc etc.

 

Ok, I see. I didn't realise.

 

6 minutes ago, LadyG said:

Some modern fridges have a freezer compartment which can be removed or kept in place as required.

I don't see the need for a full sized freezer on the inland waterways, just stock up at Aldi  for main food and drink, then top up with bread and milk as you pass by villages. The only food I buy frozen is things like chicken burghers, fish cakes, and ice lollies, they all come in small packets and are consumed within days.

It's not a good idea to buy fresh food and then freeze it, there is no cost saving and it's not going to be as good as frozen foods. Unless you are thinking of bringing frozen ready meals from home, to cut out cooking on the boat?

 

I don't have a full sized freezer. As I said, it's a small tabletop freezer. I seldom freeze fresh food but some frozen food is actually fresher than "fresh food" - fish for example. It's also much cheaper. I find it quite useful while on shore power, but as I also stated in my OP, I would do without it if I was just charging on solar.

Edited by blackrose
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16 minutes ago, Alan de Enfield said:

 

Blackrose does have a 'big fatty' boat !

In that case he may well get enough it to provide enough output for much of the year, but I still think quantity rather than chase the highest output technology.

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2 minutes ago, Tony Brooks said:

In that case he may well get enough it to provide enough output for much of the year, but I still think quantity rather than chase the highest output technology.

 

Ok so the panel technology is secondary and doesn't make that much difference? I could just get as much output as possible, but is it possible to have too much that could damage the controller or the batteries?

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20 minutes ago, blackrose said:

 

Ok so the panel technology is secondary and doesn't make that much difference? I could just get as much output as possible, but is it possible to have too much that could damage the controller or the batteries?

The technology will make some difference but probably not as much as extra panels will make. Also, some "new" technology seem to give higher outputs under certain conditions but not in others so unless you can replicate those conditions you would be paying money for nothing

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3 hours ago, blackrose said:

 

Mono solar, Monocrystalline solar, Mono percium solar, etc. Are they all the same?

 

Monocrystalline panels , often abbreviated to mono, use a single silicon crystal to a unit.

Polycrystalline panels , often abbreviated to poly, use a multiple silicon crystals to a unit.

Monos are supposed to be more efficient than poly, but you generally pay more for them of course.

 

Perc or Passivated Emitter and Rear Cell, is another technology that is apparently better, which can be combined with Mono is seems, although better than what I'm not sure.

 

I'd check the specs and look at efficiency ratings, and also calculate the price per W (of that efficiency).

 

Then look at the size of your roof, avoiding obstacles and it will probably narrow the choice down a bit, get the most efficient panel that makes the best use of the roof space.

 

I'd get larger, better panels now, and plan to add to them later if you find you need more capacity. Buying a cheap panel that wastes space would be the worst as you'd probably bin it later if you wanted more panels in the future.

 

The price variation for suppliers was also quite extreme when I was researching, I ended up with some much more efficient Victron panels (with a much longer warranty) that came out cheaper than some unbranded units just by switching between a reputable/popular supplier.

 

 

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