Hi all
I’d like to share my experiences and offer a few suggestions and maybe tips, just because I think sharing information is the way to go. This is not going to be a review or a request for help.
So here goes. We live in a small cottage away from the grid so, after years of upgrading and upsizing our stand alone solar power system, we decided we wanted a simple ’ plug and play’ system requiring minimal maintenance. We purchased an AC300 and a B300S battery. The battery was faulty so we sent both units back and received a full refund. Partly due to availability issues, and partly due to the sense that bigger would be better, we purchased an AC500 and 2 B300k batteries. I’ve posted elsewhere about the need to have the 2 bigger battery cables to take full advantage of the AC500 AC output capacity. With that sorted, I connected our 4 x 265 watt solar panels as 2 strings, 1 into each PV input. It has been working fine, although a bit under-powered. This is an issue with a bigger unit such as the AC500 as it self-consumes around 35 watts when AC and DC output are turned on. 35 watts doesn’t matter much if you have enough PV input and enough batteries.
In the last few weeks we have replaced our 4 x 265 watt solar panels with 8 x 440 watt panels, again as 2 strings (i.e. in series). Rated voltage is around 130v. We could have gone for the next size up in panels which was 490w, but this would have brought the voltage up to 149.5v. Still under the 150w maximum that the AC500 will accept, but I had heard that you need a bit of leeway to allow for voltage peaks (colder weather, edge of cloud, I think were the 2 that were mentioned to me).
So, I connected up the new panels, 4 to each PV input and flicked the switches ( I have dual pole isolators) and - big anti-climax, nothing happened. No watts, No volts, No amps showing on the AC500 screen. After trouble shooting, I realised that I had crossed the polarity on one of the cables ( you’ve got to keep focused when you connect those MC4 connecters, don’t you?). I disconnected the string with the faulty cable and the other string (PV1) started working. Then I fixed the faulty cable with new MC4s on the correct wires. Then I went to turn on the other input (PV2) while leaving PV1 running. this time I got an alarm PV2 input voltage too high -153v. And then the same message for PV1. It seems that there isn’t much, if any leeway in the AC500 to allow for a bit of over voltage.
After a bit of trial and error, I came to realise that although there are 2 ‘separate’ MPPT controllers in the AC500 unit, they are very much interlinked and are influenced by what the other is doing. So in my case I needed to turn both PV1 and PV2 on at the same time. Having done this, the system is now working correctly.
We will probably get a couple more batteries when we can afford to.
Some other observations/things I have learnt. The first thing I learned is that unless you really like geeking out with this stuff, then get it working and LEAVE IT ALONE. In other words, don’t be tempted to try out all the settings etc, just because you can. If you want to keep your life simple, get it working and let it do it’s thing.
Second, I really like this unit, especially the fact that it has so many built in alarms/protections.
Third. we have been using a Honda invertor generator - one of the old 2KVa models with ‘Eco throttle’. If you are using one of these for charging the batteries, turn the Eco throttle off. The AC500 and the generator confuse each other when there is a load on the AC output of the AC500, and it will likely stop charging and the generator will go into a high throttle- low throttle dance. You can still get the occasional ‘Grid Ripple’ fault( I think that’s what it’s called) even with the Eco throttle turned off. Anyway, I don’[t think we’ll be needing the trusty old Honda generator much now that we have the new panels installed.
That’s all from me - thanks for reading.
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