Hi, I’m Allan from CT, USA. The 8kW generator on my yacht just died, and I’m exploring the idea of replacing it with a solar generator. I don’t think I need 8kW, as I don’t need to run all the AC appliances and all three air-conditioners at once! Instead a generator that will run a small fridge, short bursts of microwave and cook stove, and occasionally an hour of ONE of the air-conditioners. Is that possible without breaking the bank on batteries?
Solar enthusiast trying to replace diesel generator on yacht
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newbostonconst
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You need to list all the loads and what they draw and then the amount of time you are going to run them...
Then calculate the size of battery/solar you need. If you do the above I am sure you will get plenty of help.
Then calculate the size of battery/solar you need. If you do the above I am sure you will get plenty of help.
rin67630
Solar Enthusiast
On a sail yacht, expect to get no more than 30% at the best from your solar panels.
The half of them will be shaded by the sails and the other half wrong oriented.
On a rainy day, calculate with 7%.
The half of them will be shaded by the sails and the other half wrong oriented.
On a rainy day, calculate with 7%.
12VoltInstalls
life passes by too quickly to not live in freedom
My thought is that you won’t have enough space to panel for an air conditioner. I’m assuming this isn’t a sailing vessel.
Diesel is “safe” on a boat. What’s the smallest diesel genset you can get?
Do basically to go solar, sure the loads are important, but how many square feet do you have for panels? That’s almost more important because that’s finite; you can manage both your loads and the batteries- especially if you suddenly are losing an 8kW pig of iron.
Diesel is “safe” on a boat. What’s the smallest diesel genset you can get?
Do basically to go solar, sure the loads are important, but how many square feet do you have for panels? That’s almost more important because that’s finite; you can manage both your loads and the batteries- especially if you suddenly are losing an 8kW pig of iron.
newbostonconst
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If they are day sailors/boaters and can charge at shore, panels really don't mater as much.
Well, I didn’t expect such a response…I’m new to this forum and am impressed. My intro post I kept short, but now that you’ve asked, here goes.
I have a 44’ Sea Ray motor yacht, no sails, room for three unshaded, large (residential size) solar panels (so maybe 1200 W), lots of room for battery size and weight when I remove the 450 lbs, 30” x 30” x 25” diesel generator. Yes, I could replace the generator with a smaller (5.5KW) unit, but I thought I would explore solar generation.
Before I detail the electrical loads I would need, let me first explain my application and likely use. We coastal cruise with our yacht, and most times we overnight in a marina, so we use shore power, no problem. When we are motoring, the twin Caterpiller diesel engines with their alternators generate more than enough energy to power our fridge and other small peripherals (WiFi router, electric fans) that run on AC power (I use a 3000W 12V-120V inverter, yeah, overkill). The real need I require is the occasional night that we spend at anchor or on a mooring, rarely if ever two nights. So I am really seeking advice on powering my AC needs for 12 hours (late afternoon to morning).
I have clamp-metered my potential AC loads during the overnight stay. NOTE: I have three air conditioning units, but I would only run the lower capacity unit for an hour or so, and only if absolutely necessary.
3/4 size fridge - 5 A (600W) Duration on = 5 hours
Two Cabin fans - 1 A (120W x 2 = 240W) Duration on = 4 hours
Two LED lights - 1 A (120W x 2 = 240W) Duration on = 4 hours
Microwave - 14 A (1680W) Duration on = 1/6th of an hour)
Cooktop - 10 A (1200W) Duration on = 1/4 of an hour
WiFi router - 1 A (120W) Duration on = 4 hours)
Salon Air conditioner - 14 A (1680W) Duration = zero!
Front cabin Air conditioner - 7 A (840W) Duration on = 0.5 hour
Aft cabin Air conditioner - 7 A (840W) Duration on = 0.5 hour
(An alternative to Air conditioning might be a dehumidifier + fans)
All the rest of the systems operate off DC from a hefty house battery bank (4 x 100 Ahr flooded batteries)
My current thoughts are to go with a 24V system, 3 400W panels in series on aft cabin roof, a Growatt “all-in-one” solar controller, inverter, charger (about 3000W capacity), and 24V lithium iron phosphate batteries (either true 24V batteries or series 12V batteries) … how much will I need is what I’m hoping you’ll help me decide, if I make this jump from diesel generator to solar generator. I think it makes sense, given my limited need for AC power at anchor/mooring. Also, the cost for a solar generator would be 1/3 that of a diesel generator, and much easier to install.
OK, probably TMI, but I thought I would lay it all out for discussion. Thanks!
I have a 44’ Sea Ray motor yacht, no sails, room for three unshaded, large (residential size) solar panels (so maybe 1200 W), lots of room for battery size and weight when I remove the 450 lbs, 30” x 30” x 25” diesel generator. Yes, I could replace the generator with a smaller (5.5KW) unit, but I thought I would explore solar generation.
Before I detail the electrical loads I would need, let me first explain my application and likely use. We coastal cruise with our yacht, and most times we overnight in a marina, so we use shore power, no problem. When we are motoring, the twin Caterpiller diesel engines with their alternators generate more than enough energy to power our fridge and other small peripherals (WiFi router, electric fans) that run on AC power (I use a 3000W 12V-120V inverter, yeah, overkill). The real need I require is the occasional night that we spend at anchor or on a mooring, rarely if ever two nights. So I am really seeking advice on powering my AC needs for 12 hours (late afternoon to morning).
I have clamp-metered my potential AC loads during the overnight stay. NOTE: I have three air conditioning units, but I would only run the lower capacity unit for an hour or so, and only if absolutely necessary.
3/4 size fridge - 5 A (600W) Duration on = 5 hours
Two Cabin fans - 1 A (120W x 2 = 240W) Duration on = 4 hours
Two LED lights - 1 A (120W x 2 = 240W) Duration on = 4 hours
Microwave - 14 A (1680W) Duration on = 1/6th of an hour)
Cooktop - 10 A (1200W) Duration on = 1/4 of an hour
WiFi router - 1 A (120W) Duration on = 4 hours)
Salon Air conditioner - 14 A (1680W) Duration = zero!
Front cabin Air conditioner - 7 A (840W) Duration on = 0.5 hour
Aft cabin Air conditioner - 7 A (840W) Duration on = 0.5 hour
(An alternative to Air conditioning might be a dehumidifier + fans)
All the rest of the systems operate off DC from a hefty house battery bank (4 x 100 Ahr flooded batteries)
My current thoughts are to go with a 24V system, 3 400W panels in series on aft cabin roof, a Growatt “all-in-one” solar controller, inverter, charger (about 3000W capacity), and 24V lithium iron phosphate batteries (either true 24V batteries or series 12V batteries) … how much will I need is what I’m hoping you’ll help me decide, if I make this jump from diesel generator to solar generator. I think it makes sense, given my limited need for AC power at anchor/mooring. Also, the cost for a solar generator would be 1/3 that of a diesel generator, and much easier to install.
OK, probably TMI, but I thought I would lay it all out for discussion. Thanks!
newbostonconst
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Comes up to just under 7kwh. So a 24 volt bank of 280ah (8cells) would work.
There are many flexible solar panels that would also work that are out now.
Can you fit a larger alternator to charge while the main engine is running. This may do it without solar.
100amp 24vdc alternator could charge it in the 3 hours of driving.
I really don't think solar is going to make a dent in the charge requirement and the shore power and alternator is where it is at.
Good Luck.....
There are many flexible solar panels that would also work that are out now.
Can you fit a larger alternator to charge while the main engine is running. This may do it without solar.
100amp 24vdc alternator could charge it in the 3 hours of driving.
I really don't think solar is going to make a dent in the charge requirement and the shore power and alternator is where it is at.
Good Luck.....
rin67630
Solar Enthusiast
So let us start to be realistic.
You will get the nominal 1200W only for a few hours around noon if your panels are oriented perfectly (which is never the case for a boat), and you have the perfect day, 100% sunny, but not too warm.
Else expect a reasonable 2-3Kwh per day as an average on mid sunny days, 200-300Wh on rainy days.
So now it's up to you to decide whether it could replace your 8KW generator, that is capable of delivering 192KWh per day.
This isn't TMI - you're actually providing enough information to be able to give any solid advice at all. We have to drag this info out of most people over the course of 5-10 posts.
I think you're (wildly) overestimating the power consumption for some of your devices, e.g. LED lights, fans and wifi router.
You could probably get a long way with a Growatt all in one and 8s2p 280 Ah lithium (14 kWh raw, 11 kWh usable), along with 1200W of solar and (preferably) adding 24V high-power alternators to your engines.
12VoltInstalls
life passes by too quickly to not live in freedom
^^^^ true
But… the projected loads COULD be effectively supported with solar almost just barely. Battery coverage is probably not a concern space-wise. More panels might erode the “maybe” some. I can see it being done. 2400W of solar would be a better plan. Don’t anchor below a bridge!
I’d nix the dehumidifier- makes a bunch of heat, uses lots of watts. Air conditioners use the watts but they put the heat outside the enclosed area.
But… the projected loads COULD be effectively supported with solar almost just barely. Battery coverage is probably not a concern space-wise. More panels might erode the “maybe” some. I can see it being done. 2400W of solar would be a better plan. Don’t anchor below a bridge!
I’d nix the dehumidifier- makes a bunch of heat, uses lots of watts. Air conditioners use the watts but they put the heat outside the enclosed area.
newbostonconst
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Listening to a generator constantly run sucks...I think batteries are a good idea... Just got to figure out how to get them charged...
Keep the ideas coming, guys, I’m learning a lot. Three observations/questions:
1. If I charge the lithiums at the dock with shore power, will they remain nearly fully charged for 8-10 hours if I go on anchor that night? I assume so. Then no or little solar is necessary. The solar would be insurance if I was going to anchor two nights.
2.I really like the alternator charging idea. If the assumption above (my #1) is true, then having the engine alternators to charge the lithiums would be good insurance. At issue here is I have no idea how my Caterpiller engine alternators are wired, and whether there is a 24V alternator to fit them…need more research, and maybe a marine electrician.
3. What about heat in the engine room where I would need to mount the batteries? I’ve read that 60 degrees C (about 140 F) is the limit. Is that right? I would need to measure the temp in the engine room while the Caterpillers were cruising (not a problem, I just haven’t done it).
1. If I charge the lithiums at the dock with shore power, will they remain nearly fully charged for 8-10 hours if I go on anchor that night? I assume so. Then no or little solar is necessary. The solar would be insurance if I was going to anchor two nights.
2.I really like the alternator charging idea. If the assumption above (my #1) is true, then having the engine alternators to charge the lithiums would be good insurance. At issue here is I have no idea how my Caterpiller engine alternators are wired, and whether there is a 24V alternator to fit them…need more research, and maybe a marine electrician.
3. What about heat in the engine room where I would need to mount the batteries? I’ve read that 60 degrees C (about 140 F) is the limit. Is that right? I would need to measure the temp in the engine room while the Caterpillers were cruising (not a problem, I just haven’t done it).
1. Yes. LiFePO4 is very good at not bleeding off a charge just sitting there. Very low self discharge. Less than about 3% monthly.
2. A 24v->12v DC-DC charger would work here. But it depends on how big your alternators are. i.e. how many amps can they put out normally.
3. Heat can be a problem. 60° C is the upper limit. I would want that to be much lower for longevity.
2. A 24v->12v DC-DC charger would work here. But it depends on how big your alternators are. i.e. how many amps can they put out normally.
3. Heat can be a problem. 60° C is the upper limit. I would want that to be much lower for longevity.
You will need a marine electrician regardless. There's a wealth of possibilities for adding alternators etc to an existing engine, suited to your battery bank and needs.
Yes, that's what I meant. A step up charger/converter is readily available. While I don't use one myself, the only ones that I'm familiar with are from Victron Energy. The 12/24-50 can produce up to 50 amps. You may be able to stack these units. Put one on each alternator for up to 100 amps. But that depends on if your battery and BMS will accept that high of a charge.
12VoltInstalls
life passes by too quickly to not live in freedom
For the money I’d suggest asking your marina about an accessory alternator that is 24V. 24V is not uncommon.
Just see what it costs/ but then again, there’s the need for different charge parameters for a lithium battery.
Unless I did the math in my head wrong, however, 2000W of solar at your indicated level of use seems like near enough just barely enough to do your tasks and recover every day. If you can fit the panels solar will meet the need. Maybe one more battery and you’re autonomous.
Just see what it costs/ but then again, there’s the need for different charge parameters for a lithium battery.
Unless I did the math in my head wrong, however, 2000W of solar at your indicated level of use seems like near enough just barely enough to do your tasks and recover every day. If you can fit the panels solar will meet the need. Maybe one more battery and you’re autonomous.
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