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--- electrical:solar:pvwatts [2023/06/16 17:49]
frater_secessus [choose a location]
+++ electrical:solar:pvwatts [2025/04/05 22:39] (current)
frater_secessus [PVWatts]
@@ Line 7: / Line 7: @@
   - find out how much panel is required to make a certain amount of Watt-hours (Wh) daily; or
   - find out how much power your existing solar setup can make
+**IMPORTANT:**  if you are depending on solar the system wattage **must be sized for location and least-sunny month** in which you will be camping.  For full-timers in the northern hemisphere this is **wherever you will be in December**.
+**Caveats:**  the estimation method describe below assumes **the panels will have a clear view of sky**.  No shade from trees, buidings, or [[opinion:frater_secessus:beginner_mistakes#mounting_or_deploying_panels_where_they_will_be_shaded|other things mounted on your van]].  No snow build-up on the panels, etc.
 ===== how much panel do I need to make X watt-hours? =====
-==== choose a location ====
+==== GET STARTED ====
@@ Line 25: / Line 27: @@
 ==== SYSTEM INFO ====
+Change TILT to 0, and accept the other defaults on this page.  The other settings won't make a difference for what we want (Hours of **F**ull **S**un **E**quivalent (FSE), which will be given on the next page).
-Accept the defaults on this page, as it won't make a difference in this case.  All we want is Hours of **F**ull **S**un **E**quivalent (FSE), which will be given on the next page.
@@ Line 69: / Line 70: @@
 ===== how much energy can my system harvest? =====
-==== choose a location ====
+==== GET STARTED ====
 First, pick a location using the search bar:
@@ Line 75: / Line 76: @@
 {{https://img.mousetrap.net/misc/pvwatts0.jpg}}
-==== system info ====
+=== SOLAR RESOURCE DATA ===
+This page shows you the location it selected. Accept the default unless it needs correcting.
+==== SYSTEM INFO ====
 We need to make a couple changes to the defaults here:
   * your array size in **kW**.  A kilowatt is 1,000w, so a 200w = 0**.**2kW (zero-point-two)((the calculator is set up like this because it is designed to model large residential and commercial installations that are measured in kW))
-  * accept the default losses for MPPT systems.  PWM systems should use something like 30%
+  * accept the default losses for MPPT systems.  PWM systems should use something like 30%((PWM doesn't really have 30% losses in the system;  on average it leaves ~30% unharvested.  The end result is the same, math-wise))
   * if your panels are flat (most are) adjust tilt to zero
@@ Line 91: / Line 96: @@
-==== results ====
+==== RESULTS ====
 The second column is kWh/square meter/**day**, AKA Hours of Full Sun Equivalent (FSE).

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