… but solar panels don’t work in the winter!

I’ve had my solar panels since October 2011 (details about my system can be found on this post) and I’m always telling people how good they are. When I tell people about my solar panels, I get one question – “how much do they generate” and the second is a statement that always makes me want to bang my head against a brick wall – “… but solar panels don’t work in the winter!” Don’t they??

When I first started telling people they should buy solar panels, all I could them was how much electricity they would generate and potentially cut from their bill, but since then I’ve added monitoring to the system which uploads the data to the internet. After the person I’m talking to has used the infamous statement about not producing electricity in the winter, I then proceed to show them the stats from my solar panels.

In the UK, winter solstice is a day between 20th and 23rd December and for more than a week each side of winter solstice, there are less than 8 hours of sunshine in a day. It’s quite literally the worst generation time of the year for solar panels in the UK – especially combined with the weather that you can get at that time of year… But when the sun does shine in the winter, you can get very good solar output days!

This December gone, I checked my system from work during lunch (as I do most days! sad, yes I know…) and noticed the solar panels had heated the hot water. To heat the hot water, there has to be enough energy generated by the solar panels to not only cover the house’ standby usage (350 ish W/h), any additional power being used by family members and also the 1kW/h immersion.

What’s more impressive is that the date was 16th December!
(the red block indicates the immersion is switched on)
16dec15

In fact we even had brief solar water heating on the 19th and 20th but they aren’t as visually impressive…
19dec1420dec14

But what all three of those charts show is that solar panels do work in the winter. They can even generate enough electricity to cause a surplus and power devices around the home!

It is true that the panels do not generate as much electricity during the winter, due to the angle of the sun in the sky and the length of the day, but we still generate in the order of 100kW/h of electricity each December.
last12monthsapr15

And on a perfect day, it’s possible to generate 9kW/h.
6dec14

Home Monitoring (home made) – Java Code

There are only 6 java classes, 1 properties file and the flow (XML) file making up the Mule application. Some of them can be better written and should be unit tested, but they work and do the job :-))

ConsumptionData.java

package uk.co.vsf.pvoutputaggregator.domain;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Map;

public class ConsumptionData extends DefaultReadingData {

	private BigDecimal milliSecondsInHour = new BigDecimal("3600000");

	private BigDecimal importWatts;
	private BigDecimal exportWatts;
	private BigDecimal msBetweenCalls;

	public ConsumptionData(@SuppressWarnings("rawtypes") Map data) {
		super((String) data.get("d"), (String) data.get("t"));
		importWatts = new BigDecimal(((String) data.get("v4")).trim());
		exportWatts = new BigDecimal(((String) data.get("v9")).trim());
		msBetweenCalls = new BigDecimal(((String) data.get("msBetweenCalls")).trim());
	}

	public BigDecimal getImportWattHours() {
		return importWatts.divide(getWattHoursDivisor(), 0, RoundingMode.HALF_EVEN);
	}

	private BigDecimal getWattHoursDivisor() {
		return msBetweenCalls.divide(milliSecondsInHour, 5, RoundingMode.HALF_EVEN);
	}

	public BigDecimal getExportWattHours() {
		if (exportWatts.compareTo(BigDecimal.ZERO) == 0) {
			return BigDecimal.ZERO;
		}
		return exportWatts.divide(getWattHoursDivisor(), 0, RoundingMode.HALF_EVEN);
	}

}

DefaultReadingData.java

package uk.co.vsf.pvoutputaggregator.domain;


class DefaultReadingData {

	private String date;
	private String time;
	
	public DefaultReadingData(String date, String time) {
		this.date = date;
		this.time = time;
	}
	
	public String getDateTime()
	{
		return "d=" + date + "&t=" + time;
	}

	public String getDate() {
		return date;
	}

	public String getTime() {
		return time;
	}
}

HotWaterData.java

package uk.co.vsf.pvoutputaggregator.domain;

import java.util.Map;

public class HotWaterData extends DefaultReadingData {

	private String hotWaterTemperature;
	private String immersionOn;

	public HotWaterData(@SuppressWarnings("rawtypes") Map data) {
		super((String) data.get("d"), (String) data.get("t"));
		hotWaterTemperature = (String) data.get("v7");
		immersionOn = (String) data.get("v8");
	}

	public String getHotWaterTemperature() {
		return hotWaterTemperature;
	}

	public String getImmersionOn() {
		return immersionOn;
	}
}

ConsumptionInputDataTransformer.java

package uk.co.vsf.pvoutputaggregator.transformer;

import java.util.Map;

import org.mule.api.MuleMessage;
import org.mule.api.transformer.TransformerException;
import org.mule.transformer.AbstractMessageTransformer;
import org.mule.transformer.AbstractTransformer;

import uk.co.vsf.pvoutputaggregator.domain.ConsumptionData;
import uk.co.vsf.pvoutputaggregator.domain.HotWaterData;

public class ConsumptionInputDataTransformer extends AbstractMessageTransformer {

	@Override
	public Object transformMessage(MuleMessage message, String outputEncoding)
			throws TransformerException {
		@SuppressWarnings("rawtypes")
		Map data = (Map) message.getPayload();
		ConsumptionData hotWaterData = new ConsumptionData(data);
		message.setCorrelationId(hotWaterData.getDateTime());
		message.setPayload(hotWaterData);
		return message;
	}

}

ExtraDataOutputTransformer.java

package uk.co.vsf.pvoutputaggregator.transformer;

import java.util.List;

import org.mule.api.MuleMessage;
import org.mule.api.transformer.TransformerException;
import org.mule.transformer.AbstractMessageTransformer;

import uk.co.vsf.pvoutputaggregator.domain.ConsumptionData;
import uk.co.vsf.pvoutputaggregator.domain.HotWaterData;

public class ExtraDataOutputTransformer extends AbstractMessageTransformer {

	@SuppressWarnings("rawtypes")
	@Override
	public Object transformMessage(MuleMessage message, String outputEncoding) throws TransformerException {
		StringBuffer pvoutputPostData = new StringBuffer(message.getCorrelationId());

		if (message.getPayload() instanceof List) {
			handleAggregatedData(pvoutputPostData, (List) message.getPayload());
		} else if (message.getPayload() instanceof ConsumptionData) {
			addConsumptionData(pvoutputPostData, (ConsumptionData) message.getPayload());
		} else {
			throw new UnsupportedOperationException();
		}

		message.setPayload(pvoutputPostData.toString());
		return message;
	}

	private void handleAggregatedData(StringBuffer pvoutputPostData, @SuppressWarnings("rawtypes") List payloadData) {
		for (Object instance : payloadData) {
			if (instance instanceof HotWaterData) {
				addHotWaterData(pvoutputPostData, (HotWaterData) instance);
			} else if (instance instanceof ConsumptionData) {
				addConsumptionData(pvoutputPostData, (ConsumptionData) instance);
			}
		}
	}

	// private void addConsumptionData(StringBuffer stringBuffer,
	// ConsumptionData consumptionData) {
	// stringBuffer.append("&v4=" +
	// consumptionData.getImportWattHours().toPlainString());
	// stringBuffer.append("&v9=" +
	// consumptionData.getExportWattHours().toPlainString());
	// }

	private void addConsumptionData(StringBuffer stringBuffer, ConsumptionData consumptionData) {
		stringBuffer.append("&v4=" + consumptionData.getImportWattHours().toPlainString());
		stringBuffer.append("&v2=" + consumptionData.getExportWattHours().toPlainString());
		stringBuffer.append("&n=1");
	}

	private void addHotWaterData(StringBuffer stringBuffer, HotWaterData hotWaterData) {
		stringBuffer.append("&v11=" + hotWaterData.getHotWaterTemperature());
		stringBuffer.append("&v10=" + hotWaterData.getImmersionOn());
	}
}

HotWaterInputDataTransformer.java

package uk.co.vsf.pvoutputaggregator.transformer;

import java.util.Map;

import org.mule.api.MuleMessage;
import org.mule.api.transformer.TransformerException;
import org.mule.transformer.AbstractMessageTransformer;

import uk.co.vsf.pvoutputaggregator.domain.HotWaterData;

public class HotWaterInputDataTransformer extends AbstractMessageTransformer {

	@Override
	public Object transformMessage(MuleMessage message, String outputEncoding)
			throws TransformerException {
		@SuppressWarnings("rawtypes")
		Map data = (Map) message.getPayload();
		HotWaterData hotWaterData = new HotWaterData(data);
		message.setCorrelationId(hotWaterData.getDateTime());
		message.setPayload(hotWaterData);
		return message;
	}

}

pvoutputaggregator.properties

correlation.aggregator.timeout=180000

http.endpoint.hotwater.port=21010
http.endpoint.hotwater.host=localhost
http.endpoint.hotwater.path=pvoutput-post-hotwater

http.endpoint.consumption.port=22010
http.endpoint.consumption.host=localhost
http.endpoint.consumption.path=pvoutput-post-consumption

X-Pvoutput-Apikey=REPLACE THIS
X-Pvoutput-SystemId=REPLACE THIS

pvoutput.endpoint=http://pvoutput.org/service/r2/addstatus.jsp
pvoutput.sentDataCopy.path=/pvoutputaggregator

pvoutputaggregator.mflow

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:file="http://www.mulesoft.org/schema/mule/file" xmlns:context="http://www.springframework.org/schema/context" xmlns:tracking="http://www.mulesoft.org/schema/mule/ee/tracking" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:vm="http://www.mulesoft.org/schema/mule/vm" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
	xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.4.1"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/vm http://www.mulesoft.org/schema/mule/vm/current/mule-vm.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/ee/tracking http://www.mulesoft.org/schema/mule/ee/tracking/current/mule-tracking-ee.xsd
http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd">
    <vm:endpoint exchange-pattern="one-way" path="ExtraDataQ" name="ExtraDataVmEndpoint" doc:name="VM"/>
    <http:connector name="GenericHttpConnector" cookieSpec="netscape" validateConnections="true" sendBufferSize="0" receiveBufferSize="0" receiveBacklog="0" clientSoTimeout="10000" serverSoTimeout="10000" socketSoLinger="0" doc:name="HTTP\HTTPS"/>
    <http:connector name="PvOutputHttpConnector" cookieSpec="netscape" validateConnections="true" sendBufferSize="0" receiveBufferSize="0" receiveBacklog="0" clientSoTimeout="10000" serverSoTimeout="10000" socketSoLinger="0" doc:name="HTTP\HTTPS"/>
    <custom-transformer class="uk.co.vsf.pvoutputaggregator.transformer.ConsumptionInputDataTransformer" name="Java" doc:name="Java"/>
    <context:property-placeholder location="classpath:/pvoutputaggregator.properties"/>
    <custom-transformer class="uk.co.vsf.pvoutputaggregator.transformer.HotWaterInputDataTransformer" name="HotWaterJava" doc:name="Java"/>
    <vm:endpoint exchange-pattern="one-way" path="PvOutputQ" name="PvOutputVmEndpoint" doc:name="VM"/>
    <file:connector name="FileConnector"  outputAppend="true" validateConnections="true" doc:name="File" autoDelete="true" streaming="true" />
    <file:endpoint path="${pvoutput.sentDataCopy.path}" outputPattern="#[function:datestamp:yyyy-MM-dd].txt" name="FileOutboundEndpoint" responseTimeout="10000" connector-ref="FileConnector" doc:name="File"/>
    <flow name="ConsumptionFlow" doc:name="ConsumptionFlow">
        <http:inbound-endpoint exchange-pattern="one-way"   doc:name="HTTP" host="${http.endpoint.consumption.host}" path="${http.endpoint.consumption.path}" port="${http.endpoint.consumption.port}" connector-ref="GenericHttpConnector"/>
        <http:body-to-parameter-map-transformer doc:name="Body to Parameter Map"/>
        <message-properties-transformer doc:name="Message Properties">
            <add-message-property key="MULE_CORRELATION_GROUP_SIZE" value="2"/>
        </message-properties-transformer>
        <transformer ref="Java" doc:name="Transformer Reference"/>
        <vm:outbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="ExtraDataVmEndpoint"/>
    </flow>
    <flow name="HotWaterFlow" doc:name="HotWaterFlow">
        <http:inbound-endpoint exchange-pattern="one-way"   doc:name="HTTP"  path="${http.endpoint.hotwater.path}" host="${http.endpoint.hotwater.host}" port="${http.endpoint.hotwater.port}" connector-ref="GenericHttpConnector"/>
        <http:body-to-parameter-map-transformer doc:name="Body to Parameter Map"/>
        <message-properties-transformer doc:name="Message Properties">
            <add-message-property key="MULE_CORRELATION_GROUP_SIZE" value="2"/>
        </message-properties-transformer>
        <transformer ref="HotWaterJava" doc:name="Transformer Reference"/>
        <vm:outbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="ExtraDataVmEndpoint"/>
    </flow>
    <flow name="ExtraDataToPvOutputFlow" doc:name="ExtraDataToPvOutputFlow">
        <vm:inbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="ExtraDataVmEndpoint"/>
        <collection-aggregator timeout="${correlation.aggregator.timeout}" failOnTimeout="true" doc:name="Collection Aggregator"/>
        <vm:outbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="PvOutputVmEndpoint"/>
        <catch-exception-strategy doc:name="Catch Exception Strategy">
            <vm:outbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="PvOutputVmEndpoint"/>
        </catch-exception-strategy>
    </flow>
    <flow name="PVOutputFlow" doc:name="PVOutputFlow">
        <vm:inbound-endpoint exchange-pattern="one-way"  doc:name="VM" ref="PvOutputVmEndpoint"/>
        <custom-transformer class="uk.co.vsf.pvoutputaggregator.transformer.ExtraDataOutputTransformer" doc:name="Java"/>
        <message-properties-transformer doc:name="Message Properties">
            <add-message-property key="X-Pvoutput-Apikey" value="${X-Pvoutput-Apikey}"/>
            <add-message-property key="X-Pvoutput-SystemId" value="${X-Pvoutput-SystemId}"/>
        </message-properties-transformer>
        <all doc:name="All">
            <processor-chain>
                <append-string-transformer message="&#xD;&#xA;" doc:name="Append String"/>
                <file:outbound-endpoint responseTimeout="10000" connector-ref="FileConnector" ref="FileOutboundEndpoint" doc:name="File"/>
            </processor-chain>
            <http:outbound-endpoint exchange-pattern="request-response" method="POST" address="${pvoutput.endpoint}" connector-ref="PvOutputHttpConnector" contentType="application/x-www-form-urlencoded" doc:name="HTTP"/>
        </all>
    </flow>
</mule>

Next Part

Part 7: And finally the results of all work!