170W Solar - Really though how many amps? 10? (1 Viewer)

[Raul]

This is todays forecast for my area, and the actual for so far in blue - batts will be full very soon so wont get the forecast, but it's surprisingly accurate normally. The forecast potential for today is 0.7kWh and tomorrow 0.8kWh - of course if the weather forecast is wrong then..... Today is overcast with 2 hours of clear sky, tomorrow is overcast rainy and no clear sky. We have 550w. So with slightly better weather we would be similar to you I guess. PS. South Coast - 10miles inland.

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Or about 1.5sun/hr in your case. I get similar results North of M25.

 

[Ian_H]

Average, as maximum without a tracker can achive 7-8 sun/hr. A tracker can do 10 sun/hrs.

Yours its doing very well, cold panels I see 266w out of a 250w if you say its a 250w, then you have a good efficient system.

OK, so in bright cold weather Chossy could have been getting more than the 1.5 sun/hr that you quoted?

 

[dawsey]

Nominal 12V panels have an OC voltage of around 20V. Under full direct sun in UK and approaching peak 170W output you should expect a peak output of approx 9A at approx 19V. Precise numbers will be written in the spec. A decent DC-DC solar charger with similar power electronics to a DC-DC charger (aka an MPPT) will drop the charge voltage by approx 30% but increase charge current by the same amount, all net of around 5% conversion loss. An old bang bang (PWM) will give about 20% less over the day, they are much less efficient in the shoulders.

on a very bright sunny day in June/July in UK with no shade you might expect a peak daily battery charge of approx 50-60Ah from an MPPT controller, maybe 40-50Ah from a PWM controller.

 

[TrudeandDall]

I've just been away for 30 days in the SW of England with mixed weather. My 280 of solar with MPPT had produced 800ah or 26ah per day average. The best output I saw was 16amps in full Cornish sunshine.
This was running a compressor fridge full time, charging 2x ebikes about 6 times, all helped by a 25 amp b2b for the 42 Hours of driving.
Net result is self sufficient even in a crappy April in the UK. The solar made all the difference.......

 

[Raul]

OK, so in bright cold weather Chossy could have been getting more than the 1.5 sun/hr that you quoted?

Absolutely, cold and sunny its best for solar harvest. Unfortunately not many days in the year with those conditions.

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[Captain Yoghurtpot]

Assuming a perfect solar system kit, on a sunny day the charging current should be about 14A but depending on the weather on other days it is likely to drop to much lower levels. If you have a large, 100Ah battery even a trickle of 2A for a 10 hour daylight day would keep it topped up provided you don’t use any equipment that draws a high current for long periods. You have already said that you will be careful so your system should be a great success. Obviously the main limitation would be long periods of really dull weather; we can all remember some weeks that were total write offs regarding sunshine.

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