Solar Panel Test-gctid814598

[joe440]

We are going to be on the hook for the next 11 days. The weather is forecast sunny, looks like this could be the best week of the current summer. I'm going to see how many days I can go without using the generator. The Admiral will use the microwave ad electric kettle every morning. The ice machine and stereo will be running all day and evening long and the fridge will be running 24/7.

3 flexible 100 watt panels on the front of the fly bridge.

[SprinterX]

11 days Joe, where abouts?

Should be a good test for the system. Keep us informed.

[freedre]

With 300 Watts, I fear you are going to be disappointed.

[joe440]

"SprinterX" post=814611 wrote:
11 days Joe, where abouts?

Should be a good test for the system. Keep us informed.

We are at Bedwell Harbour. We'll do day trips from here on the Waverunner.

If any BOC members are around, stop by and say hello.

[joe440]

"freedre" post=814636 wrote:
With 300 Watts, I fear you are going to be disappointed.

I know we can do a weekend.

[TenMile]

Joe - did you install a battery monitor that calculates State of Charge (SOC)?

[mlewis100]

300 watts = 25 amps (at best on a perfect day)

Based on 6 hours of full production= 150 amps per day (sugar coated).

The fridge might be around 50-60 amps per day depending on a number of factors.

Depending on the ice maker, that could use a fair bit of juice.

The electric kettle and microwave use a pretty big draw but at least this will be early in the day perhaps give a good chance to recover the amps through the day.

If you run the generator during the use of the kettle and/or microwave usage that would help.

How many amp hours is your total house battery bank? Battery configuration?

Please reply back to this post after your trip with your experience and observations. It is always interesting to know the real-world characteristics compared to the specs.

Have a safe trip!

[tower3218]

Don't count on 6 hrs of full production a day. At best, you will get a maximum of 2 - 3 hours unless you constantly tilt the panels towards the moving sun.

[hfxjack]

You should go to Ganges for the long weekend . The fireworks are great

[Solandri]

"tower3218" post=814656 wrote:
Don't count on 6 hrs of full production a day. At best, you will get a maximum of 2 - 3 hours unless you constantly tilt the panels towards the moving sun.

Just go to the government PWatts site and enter the numbers for your PV solar panels. It takes into account latitude (angle of the sun, length of day) and typical weather conditions for the area. The site doesn't deal well with less than 1 kW of panels, so just enter the number of Watts instead of kW (e.g. enter 300 Watts as 300 kW), and divide the production amounts by 1000.

http://pvwatts.nrel.gov/

Enter 0 degrees for the tilt. Since you're interested in DC production, under advanced parameters enter 1.0 for DC to AC size ratio, 99.5% for inverter efficiency (highest you can set it), and 0 for ground coverage ratio (to reflect the panels being horizontal).

Entering 300 Watts for Blaine, WA (closest point in U.S. to British Columbia) yields a peak production of 46.2 kWh for July, which at 31 days works out to 1.49 kWh produced per day. That's 1490 Wh / (300 Watts * 24 h) = 0.207 capacity factor for July, which is slightly better than the annual average for the desert Southwest U.S. Or put another way, that's equivalent to 24h * 0.207 = 4.97 hours of peak production per day (zero production the other 19.03 hours).

Year-round production will be 300.8 kWh, which translates into a capacity factor of 0.114, which is about what you'd expect at that latitude. Equivalent to 2.7 hours of peak production (0.824 kWh) per day.

Somewhat disheartening, at an electricity price of 7 cents/kWh, your panels only generate $20 worth of electricity per year. Or an annual average production of 5.6 cents worth of electricity per day.

[SprinterX]

"hfxjack" post=814720 wrote:
You should go to Ganges for the long weekend . The fireworks are great

That's what I told him too.

[joe440]

"SprinterX" post=814731 wrote:

"hfxjack" post=814720 wrote:
You should go to Ganges for the long weekend . The fireworks are great

That's what I told him too.

Not sure. Admiral has her own ideas. lol

[joe440]

Things ant going as expected. Lots of wind today. My solar panels were facing the wrong direction most of the day. Still running on batteries. 12.8 volts reading on my solar controller as I go to bed.

[freedre]

"Solandri" post=814728 wrote:


Somewhat disheartening, at an electricity price of 7 cents/kWh, your panels only generate $20 worth of electricity per year. Or an annual average production of 5.6 cents worth of electricity per day.

The problem with this analogy is that we are talking about boats - not homes. The cost of power on your boat is considerably higher than 7 cents/kWh. The solar panels are are a substitute for on board generators, not commercial power.

When viewed from this perspective, solar panels are much more attractive.

[Solandri]

"freedre" post=814741 wrote:

"Solandri" post=814728 wrote:
Somewhat disheartening, at an electricity price of 7 cents/kWh, your panels only generate $20 worth of electricity per year. Or an annual average production of 5.6 cents worth of electricity per day.

The problem with this analogy is that we are talking about boats - not homes. The cost of power on your boat is considerably higher than 7 cents/kWh. The solar panels are are a substitute for on board generators, not commercial power.

When viewed from this perspective, solar panels are much more attractive.

True that. I was thinking more in terms of value of electricity produced. Back in my grad school days, our EE crunched some numbers and calculated we were spending $20,000 on batteries to carry around 13 cents worth of electricity in our robot submarine.

Anyhow, the Honda EU2000i is rated at 1600W and 3.4 hours from 0.95 gallons at that output. At $3/gal for gas, that's ($3/gal * 0.95 gallons) / (1.6 kW * 3.4 hours) = 52.4 cents/kWh.

At 1/4 load (400 Watts), it gets 8.1 hours. So that works out to ($3/gal * 0.95 gallons) / (0.4 kW * 8.1 hours) = 88.0 cents/kWh.