Blown Enphase Q relay (3 phase) - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: August 17, 2021, 05:25:05 pm
content: Today I was visiting someone who happened to have a small solar panel setup. About 3kW of panels spread across 3 phases. A problem with the system is that appearantly on very sunny days the Enphase Q relay (*) blows up in combination with switching other loads (like a vacuum cleaner). The system already went through two of these relays and the owner is reluctant to change the relay again waiting for it to fail again.I wasn't there to look at the solar system but couldn't resist myself and opened up the Q relay. I found that there are MOVs and transzorbs between the lines and neutral. For one phase the MOV and transzorb failed spectaculary (=blown apart). My assumption is that the mains voltage is already high and a small pulse is enough to push the voltage over the limit.Has anyone had similar experiences with these kind of relays? Are there other models compatible with the micro inverters from Enphase which have more margin?* The Q relay disconnects the solar array in case there is something wrong with the mains voltage. Local code requires to have this relay but the system would work just fine without it.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 17, 2021, 06:34:48 pm
content: Measure the line voltage. Probably way too high as standard in suburbs with too many pv.Then q-relay then “opens”, and the poor pcb relays will have a bad day.Maybe wire a true Schneider contractor operated by the q-relay instead of using the q-relay itself.You must have the q-relay installed and talking for the grid profile to work, unless you can still change the grid profile to something where the q-relay isn’t required in the toolkit.

author: nctnico
author_rank: Super Contributor
timestamp: August 18, 2021, 05:04:17 am
content: Quote from: Jeroen3 on August 17, 2021, 06:34:48 pmThe PCB relays look just fine. It is the overvoltage protection at the grid side which has been destroyed.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 18, 2021, 05:39:16 am
content: You can measure the voltage after the main isolator on a sunny day, not like today, saturday perhaps. And measure at the q-relay.If they measure significantly different, verify the cable and connections, you may have voltage drop.Otherwise write to Liander/Stedin or whomever to request they fix the high voltage in the area.You can attach a raspberry pi to your smart meter and install P1 Monitor and enable the logging for the voltage the smart meter reports.https://www.sossolutions.nl/slimme-meter-domoticz-starter-met-raspberry-pi3bhttps://www.ztatz.nl/p1-monitor/If your smart meter reports the voltage....

author: mansaxel
author_rank: Super Contributor
timestamp: August 18, 2021, 05:46:51 am
content: Quote from: nctnico on August 18, 2021, 05:04:17 am1. transient logging? It's entirely possible that the grid is being stressed with microproducers going off and coming on-line, even though the most dramatic transients come from larger grid partition events; If a relatively big consumer drops off a somewhat narrowly connected part of the grid there is going to be a voltage surge from the sudden increase in impedance.2. Better protection on the grid connection, outside of the PV in-a-box solution. If the above can be concluded, there may be a case against the grid company for exceeding the parameters of the service. They can solve that by fattening the grid or bodging protection onto consumer connections.

author: nctnico
author_rank: Super Contributor
timestamp: August 19, 2021, 01:31:33 pm
content: One of the ideas I have is to use a transformer to bring the line voltage to the solar panel system down -say 10%-. A variac (for each phase) might be an option to try

author: mansaxel
author_rank: Super Contributor
timestamp: August 19, 2021, 07:24:58 pm
content: Quote from: nctnico on August 19, 2021, 01:31:33 pmIf you're being hit with surges that won't help. Unless there's something getting annoyed by the galvanic connection that a transformer would break.

author: nctnico
author_rank: Super Contributor
timestamp: August 19, 2021, 07:41:34 pm
content: Quote from: mansaxel on August 19, 2021, 07:24:58 pmFrom what I have gathered I think the problem is a combination between the line voltage being too high, surges and an overvoltage protection circuit which trips at a voltage which is too low for practical purposes. Measuring the line voltage on a sunny day should give more insight but I doubt I'll be doing that measurement.

author: bdunham7
author_rank: Super Contributor
timestamp: August 19, 2021, 08:04:13 pm
content: If the PCB itself survived you could try replacing all of the devices with ones rated for 10-20% more voltage. If you move the trigger points up 20% and they still blow, then there are some serious problems with the power. It would be interesting to know if it was the same phase that exploded on both relays.

author: f4eru
author_rank: Super Contributor
timestamp: August 19, 2021, 08:04:49 pm
content: Why not measure ? Why not confirm or disprove the root cause ?

author: tszaboo
author_rank: Super Contributor
timestamp: August 19, 2021, 08:12:11 pm
content: Quote from: Jeroen3 on August 17, 2021, 06:34:48 pmThe line voltage because of solar panels cannot be "way too high". Meaning that they reduce or switch off the output, if the line voltage is too high.I've participated in a project, where we were actively searching for inverters that were doing this (in Belgium), so we had data from the generation every 15 minutes (green certificate trading) address, we got weather data, we compared it to installations in the vicinity and so on. Big data. I think 5% of the installations were losing like 50 EUR per year, because the inverter reduced output because the line voltage.It can be "high, yet within the specification of the network".

author: bdunham7
author_rank: Super Contributor
timestamp: August 19, 2021, 08:28:50 pm
content: Quote from: tszaboo on August 19, 2021, 08:12:11 pmEnphase has an option where you can adjust the default limits for voltage and frequency if your local regulations permit a wider operating range. I'm not sure whether they offer that in your jurisdiction.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 21, 2021, 04:41:04 pm
content: Perhaps install a whole house surge protector and add 10 ohm or so fusible power resistors on the input of the relay module, then use the output to switch a contactor?